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Linux/mm/memory.c

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  1 /*
  2  *  linux/mm/memory.c
  3  *
  4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  5  */
  6 
  7 /*
  8  * demand-loading started 01.12.91 - seems it is high on the list of
  9  * things wanted, and it should be easy to implement. - Linus
 10  */
 11 
 12 /*
 13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
 14  * pages started 02.12.91, seems to work. - Linus.
 15  *
 16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
 17  * would have taken more than the 6M I have free, but it worked well as
 18  * far as I could see.
 19  *
 20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
 21  */
 22 
 23 /*
 24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
 25  * thought has to go into this. Oh, well..
 26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
 27  *              Found it. Everything seems to work now.
 28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
 29  */
 30 
 31 /*
 32  * 05.04.94  -  Multi-page memory management added for v1.1.
 33  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
 34  *
 35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
 36  *              (Gerhard.Wichert@pdb.siemens.de)
 37  *
 38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
 39  */
 40 
 41 #include <linux/kernel_stat.h>
 42 #include <linux/mm.h>
 43 #include <linux/sched/mm.h>
 44 #include <linux/sched/coredump.h>
 45 #include <linux/sched/numa_balancing.h>
 46 #include <linux/sched/task.h>
 47 #include <linux/hugetlb.h>
 48 #include <linux/mman.h>
 49 #include <linux/swap.h>
 50 #include <linux/highmem.h>
 51 #include <linux/pagemap.h>
 52 #include <linux/memremap.h>
 53 #include <linux/ksm.h>
 54 #include <linux/rmap.h>
 55 #include <linux/export.h>
 56 #include <linux/delayacct.h>
 57 #include <linux/init.h>
 58 #include <linux/pfn_t.h>
 59 #include <linux/writeback.h>
 60 #include <linux/memcontrol.h>
 61 #include <linux/mmu_notifier.h>
 62 #include <linux/kallsyms.h>
 63 #include <linux/swapops.h>
 64 #include <linux/elf.h>
 65 #include <linux/gfp.h>
 66 #include <linux/migrate.h>
 67 #include <linux/string.h>
 68 #include <linux/dma-debug.h>
 69 #include <linux/debugfs.h>
 70 #include <linux/userfaultfd_k.h>
 71 #include <linux/dax.h>
 72 #include <linux/oom.h>
 73 
 74 #include <asm/io.h>
 75 #include <asm/mmu_context.h>
 76 #include <asm/pgalloc.h>
 77 #include <linux/uaccess.h>
 78 #include <asm/tlb.h>
 79 #include <asm/tlbflush.h>
 80 #include <asm/pgtable.h>
 81 
 82 #include "internal.h"
 83 
 84 #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
 85 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
 86 #endif
 87 
 88 #ifndef CONFIG_NEED_MULTIPLE_NODES
 89 /* use the per-pgdat data instead for discontigmem - mbligh */
 90 unsigned long max_mapnr;
 91 EXPORT_SYMBOL(max_mapnr);
 92 
 93 struct page *mem_map;
 94 EXPORT_SYMBOL(mem_map);
 95 #endif
 96 
 97 /*
 98  * A number of key systems in x86 including ioremap() rely on the assumption
 99  * that high_memory defines the upper bound on direct map memory, then end
100  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
101  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
102  * and ZONE_HIGHMEM.
103  */
104 void *high_memory;
105 EXPORT_SYMBOL(high_memory);
106 
107 /*
108  * Randomize the address space (stacks, mmaps, brk, etc.).
109  *
110  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
111  *   as ancient (libc5 based) binaries can segfault. )
112  */
113 int randomize_va_space __read_mostly =
114 #ifdef CONFIG_COMPAT_BRK
115                                         1;
116 #else
117                                         2;
118 #endif
119 
120 static int __init disable_randmaps(char *s)
121 {
122         randomize_va_space = 0;
123         return 1;
124 }
125 __setup("norandmaps", disable_randmaps);
126 
127 unsigned long zero_pfn __read_mostly;
128 EXPORT_SYMBOL(zero_pfn);
129 
130 unsigned long highest_memmap_pfn __read_mostly;
131 
132 /*
133  * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
134  */
135 static int __init init_zero_pfn(void)
136 {
137         zero_pfn = page_to_pfn(ZERO_PAGE(0));
138         return 0;
139 }
140 core_initcall(init_zero_pfn);
141 
142 
143 #if defined(SPLIT_RSS_COUNTING)
144 
145 void sync_mm_rss(struct mm_struct *mm)
146 {
147         int i;
148 
149         for (i = 0; i < NR_MM_COUNTERS; i++) {
150                 if (current->rss_stat.count[i]) {
151                         add_mm_counter(mm, i, current->rss_stat.count[i]);
152                         current->rss_stat.count[i] = 0;
153                 }
154         }
155         current->rss_stat.events = 0;
156 }
157 
158 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
159 {
160         struct task_struct *task = current;
161 
162         if (likely(task->mm == mm))
163                 task->rss_stat.count[member] += val;
164         else
165                 add_mm_counter(mm, member, val);
166 }
167 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
168 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
169 
170 /* sync counter once per 64 page faults */
171 #define TASK_RSS_EVENTS_THRESH  (64)
172 static void check_sync_rss_stat(struct task_struct *task)
173 {
174         if (unlikely(task != current))
175                 return;
176         if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
177                 sync_mm_rss(task->mm);
178 }
179 #else /* SPLIT_RSS_COUNTING */
180 
181 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
182 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
183 
184 static void check_sync_rss_stat(struct task_struct *task)
185 {
186 }
187 
188 #endif /* SPLIT_RSS_COUNTING */
189 
190 #ifdef HAVE_GENERIC_MMU_GATHER
191 
192 static bool tlb_next_batch(struct mmu_gather *tlb)
193 {
194         struct mmu_gather_batch *batch;
195 
196         batch = tlb->active;
197         if (batch->next) {
198                 tlb->active = batch->next;
199                 return true;
200         }
201 
202         if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
203                 return false;
204 
205         batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
206         if (!batch)
207                 return false;
208 
209         tlb->batch_count++;
210         batch->next = NULL;
211         batch->nr   = 0;
212         batch->max  = MAX_GATHER_BATCH;
213 
214         tlb->active->next = batch;
215         tlb->active = batch;
216 
217         return true;
218 }
219 
220 void arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
221                                 unsigned long start, unsigned long end)
222 {
223         tlb->mm = mm;
224 
225         /* Is it from 0 to ~0? */
226         tlb->fullmm     = !(start | (end+1));
227         tlb->need_flush_all = 0;
228         tlb->local.next = NULL;
229         tlb->local.nr   = 0;
230         tlb->local.max  = ARRAY_SIZE(tlb->__pages);
231         tlb->active     = &tlb->local;
232         tlb->batch_count = 0;
233 
234 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
235         tlb->batch = NULL;
236 #endif
237         tlb->page_size = 0;
238 
239         __tlb_reset_range(tlb);
240 }
241 
242 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
243 {
244         if (!tlb->end)
245                 return;
246 
247         tlb_flush(tlb);
248         mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
249 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
250         tlb_table_flush(tlb);
251 #endif
252         __tlb_reset_range(tlb);
253 }
254 
255 static void tlb_flush_mmu_free(struct mmu_gather *tlb)
256 {
257         struct mmu_gather_batch *batch;
258 
259         for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
260                 free_pages_and_swap_cache(batch->pages, batch->nr);
261                 batch->nr = 0;
262         }
263         tlb->active = &tlb->local;
264 }
265 
266 void tlb_flush_mmu(struct mmu_gather *tlb)
267 {
268         tlb_flush_mmu_tlbonly(tlb);
269         tlb_flush_mmu_free(tlb);
270 }
271 
272 /* tlb_finish_mmu
273  *      Called at the end of the shootdown operation to free up any resources
274  *      that were required.
275  */
276 void arch_tlb_finish_mmu(struct mmu_gather *tlb,
277                 unsigned long start, unsigned long end, bool force)
278 {
279         struct mmu_gather_batch *batch, *next;
280 
281         if (force)
282                 __tlb_adjust_range(tlb, start, end - start);
283 
284         tlb_flush_mmu(tlb);
285 
286         /* keep the page table cache within bounds */
287         check_pgt_cache();
288 
289         for (batch = tlb->local.next; batch; batch = next) {
290                 next = batch->next;
291                 free_pages((unsigned long)batch, 0);
292         }
293         tlb->local.next = NULL;
294 }
295 
296 /* __tlb_remove_page
297  *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
298  *      handling the additional races in SMP caused by other CPUs caching valid
299  *      mappings in their TLBs. Returns the number of free page slots left.
300  *      When out of page slots we must call tlb_flush_mmu().
301  *returns true if the caller should flush.
302  */
303 bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
304 {
305         struct mmu_gather_batch *batch;
306 
307         VM_BUG_ON(!tlb->end);
308         VM_WARN_ON(tlb->page_size != page_size);
309 
310         batch = tlb->active;
311         /*
312          * Add the page and check if we are full. If so
313          * force a flush.
314          */
315         batch->pages[batch->nr++] = page;
316         if (batch->nr == batch->max) {
317                 if (!tlb_next_batch(tlb))
318                         return true;
319                 batch = tlb->active;
320         }
321         VM_BUG_ON_PAGE(batch->nr > batch->max, page);
322 
323         return false;
324 }
325 
326 #endif /* HAVE_GENERIC_MMU_GATHER */
327 
328 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
329 
330 /*
331  * See the comment near struct mmu_table_batch.
332  */
333 
334 static void tlb_remove_table_smp_sync(void *arg)
335 {
336         /* Simply deliver the interrupt */
337 }
338 
339 static void tlb_remove_table_one(void *table)
340 {
341         /*
342          * This isn't an RCU grace period and hence the page-tables cannot be
343          * assumed to be actually RCU-freed.
344          *
345          * It is however sufficient for software page-table walkers that rely on
346          * IRQ disabling. See the comment near struct mmu_table_batch.
347          */
348         smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
349         __tlb_remove_table(table);
350 }
351 
352 static void tlb_remove_table_rcu(struct rcu_head *head)
353 {
354         struct mmu_table_batch *batch;
355         int i;
356 
357         batch = container_of(head, struct mmu_table_batch, rcu);
358 
359         for (i = 0; i < batch->nr; i++)
360                 __tlb_remove_table(batch->tables[i]);
361 
362         free_page((unsigned long)batch);
363 }
364 
365 void tlb_table_flush(struct mmu_gather *tlb)
366 {
367         struct mmu_table_batch **batch = &tlb->batch;
368 
369         if (*batch) {
370                 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
371                 *batch = NULL;
372         }
373 }
374 
375 void tlb_remove_table(struct mmu_gather *tlb, void *table)
376 {
377         struct mmu_table_batch **batch = &tlb->batch;
378 
379         /*
380          * When there's less then two users of this mm there cannot be a
381          * concurrent page-table walk.
382          */
383         if (atomic_read(&tlb->mm->mm_users) < 2) {
384                 __tlb_remove_table(table);
385                 return;
386         }
387 
388         if (*batch == NULL) {
389                 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
390                 if (*batch == NULL) {
391                         tlb_remove_table_one(table);
392                         return;
393                 }
394                 (*batch)->nr = 0;
395         }
396         (*batch)->tables[(*batch)->nr++] = table;
397         if ((*batch)->nr == MAX_TABLE_BATCH)
398                 tlb_table_flush(tlb);
399 }
400 
401 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
402 
403 /* tlb_gather_mmu
404  *      Called to initialize an (on-stack) mmu_gather structure for page-table
405  *      tear-down from @mm. The @fullmm argument is used when @mm is without
406  *      users and we're going to destroy the full address space (exit/execve).
407  */
408 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
409                         unsigned long start, unsigned long end)
410 {
411         arch_tlb_gather_mmu(tlb, mm, start, end);
412         inc_tlb_flush_pending(tlb->mm);
413 }
414 
415 void tlb_finish_mmu(struct mmu_gather *tlb,
416                 unsigned long start, unsigned long end)
417 {
418         /*
419          * If there are parallel threads are doing PTE changes on same range
420          * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
421          * flush by batching, a thread has stable TLB entry can fail to flush
422          * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
423          * forcefully if we detect parallel PTE batching threads.
424          */
425         bool force = mm_tlb_flush_nested(tlb->mm);
426 
427         arch_tlb_finish_mmu(tlb, start, end, force);
428         dec_tlb_flush_pending(tlb->mm);
429 }
430 
431 /*
432  * Note: this doesn't free the actual pages themselves. That
433  * has been handled earlier when unmapping all the memory regions.
434  */
435 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
436                            unsigned long addr)
437 {
438         pgtable_t token = pmd_pgtable(*pmd);
439         pmd_clear(pmd);
440         pte_free_tlb(tlb, token, addr);
441         mm_dec_nr_ptes(tlb->mm);
442 }
443 
444 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
445                                 unsigned long addr, unsigned long end,
446                                 unsigned long floor, unsigned long ceiling)
447 {
448         pmd_t *pmd;
449         unsigned long next;
450         unsigned long start;
451 
452         start = addr;
453         pmd = pmd_offset(pud, addr);
454         do {
455                 next = pmd_addr_end(addr, end);
456                 if (pmd_none_or_clear_bad(pmd))
457                         continue;
458                 free_pte_range(tlb, pmd, addr);
459         } while (pmd++, addr = next, addr != end);
460 
461         start &= PUD_MASK;
462         if (start < floor)
463                 return;
464         if (ceiling) {
465                 ceiling &= PUD_MASK;
466                 if (!ceiling)
467                         return;
468         }
469         if (end - 1 > ceiling - 1)
470                 return;
471 
472         pmd = pmd_offset(pud, start);
473         pud_clear(pud);
474         pmd_free_tlb(tlb, pmd, start);
475         mm_dec_nr_pmds(tlb->mm);
476 }
477 
478 static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
479                                 unsigned long addr, unsigned long end,
480                                 unsigned long floor, unsigned long ceiling)
481 {
482         pud_t *pud;
483         unsigned long next;
484         unsigned long start;
485 
486         start = addr;
487         pud = pud_offset(p4d, addr);
488         do {
489                 next = pud_addr_end(addr, end);
490                 if (pud_none_or_clear_bad(pud))
491                         continue;
492                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
493         } while (pud++, addr = next, addr != end);
494 
495         start &= P4D_MASK;
496         if (start < floor)
497                 return;
498         if (ceiling) {
499                 ceiling &= P4D_MASK;
500                 if (!ceiling)
501                         return;
502         }
503         if (end - 1 > ceiling - 1)
504                 return;
505 
506         pud = pud_offset(p4d, start);
507         p4d_clear(p4d);
508         pud_free_tlb(tlb, pud, start);
509         mm_dec_nr_puds(tlb->mm);
510 }
511 
512 static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
513                                 unsigned long addr, unsigned long end,
514                                 unsigned long floor, unsigned long ceiling)
515 {
516         p4d_t *p4d;
517         unsigned long next;
518         unsigned long start;
519 
520         start = addr;
521         p4d = p4d_offset(pgd, addr);
522         do {
523                 next = p4d_addr_end(addr, end);
524                 if (p4d_none_or_clear_bad(p4d))
525                         continue;
526                 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
527         } while (p4d++, addr = next, addr != end);
528 
529         start &= PGDIR_MASK;
530         if (start < floor)
531                 return;
532         if (ceiling) {
533                 ceiling &= PGDIR_MASK;
534                 if (!ceiling)
535                         return;
536         }
537         if (end - 1 > ceiling - 1)
538                 return;
539 
540         p4d = p4d_offset(pgd, start);
541         pgd_clear(pgd);
542         p4d_free_tlb(tlb, p4d, start);
543 }
544 
545 /*
546  * This function frees user-level page tables of a process.
547  */
548 void free_pgd_range(struct mmu_gather *tlb,
549                         unsigned long addr, unsigned long end,
550                         unsigned long floor, unsigned long ceiling)
551 {
552         pgd_t *pgd;
553         unsigned long next;
554 
555         /*
556          * The next few lines have given us lots of grief...
557          *
558          * Why are we testing PMD* at this top level?  Because often
559          * there will be no work to do at all, and we'd prefer not to
560          * go all the way down to the bottom just to discover that.
561          *
562          * Why all these "- 1"s?  Because 0 represents both the bottom
563          * of the address space and the top of it (using -1 for the
564          * top wouldn't help much: the masks would do the wrong thing).
565          * The rule is that addr 0 and floor 0 refer to the bottom of
566          * the address space, but end 0 and ceiling 0 refer to the top
567          * Comparisons need to use "end - 1" and "ceiling - 1" (though
568          * that end 0 case should be mythical).
569          *
570          * Wherever addr is brought up or ceiling brought down, we must
571          * be careful to reject "the opposite 0" before it confuses the
572          * subsequent tests.  But what about where end is brought down
573          * by PMD_SIZE below? no, end can't go down to 0 there.
574          *
575          * Whereas we round start (addr) and ceiling down, by different
576          * masks at different levels, in order to test whether a table
577          * now has no other vmas using it, so can be freed, we don't
578          * bother to round floor or end up - the tests don't need that.
579          */
580 
581         addr &= PMD_MASK;
582         if (addr < floor) {
583                 addr += PMD_SIZE;
584                 if (!addr)
585                         return;
586         }
587         if (ceiling) {
588                 ceiling &= PMD_MASK;
589                 if (!ceiling)
590                         return;
591         }
592         if (end - 1 > ceiling - 1)
593                 end -= PMD_SIZE;
594         if (addr > end - 1)
595                 return;
596         /*
597          * We add page table cache pages with PAGE_SIZE,
598          * (see pte_free_tlb()), flush the tlb if we need
599          */
600         tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
601         pgd = pgd_offset(tlb->mm, addr);
602         do {
603                 next = pgd_addr_end(addr, end);
604                 if (pgd_none_or_clear_bad(pgd))
605                         continue;
606                 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
607         } while (pgd++, addr = next, addr != end);
608 }
609 
610 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
611                 unsigned long floor, unsigned long ceiling)
612 {
613         while (vma) {
614                 struct vm_area_struct *next = vma->vm_next;
615                 unsigned long addr = vma->vm_start;
616 
617                 /*
618                  * Hide vma from rmap and truncate_pagecache before freeing
619                  * pgtables
620                  */
621                 unlink_anon_vmas(vma);
622                 unlink_file_vma(vma);
623 
624                 if (is_vm_hugetlb_page(vma)) {
625                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
626                                 floor, next ? next->vm_start : ceiling);
627                 } else {
628                         /*
629                          * Optimization: gather nearby vmas into one call down
630                          */
631                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
632                                && !is_vm_hugetlb_page(next)) {
633                                 vma = next;
634                                 next = vma->vm_next;
635                                 unlink_anon_vmas(vma);
636                                 unlink_file_vma(vma);
637                         }
638                         free_pgd_range(tlb, addr, vma->vm_end,
639                                 floor, next ? next->vm_start : ceiling);
640                 }
641                 vma = next;
642         }
643 }
644 
645 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
646 {
647         spinlock_t *ptl;
648         pgtable_t new = pte_alloc_one(mm, address);
649         if (!new)
650                 return -ENOMEM;
651 
652         /*
653          * Ensure all pte setup (eg. pte page lock and page clearing) are
654          * visible before the pte is made visible to other CPUs by being
655          * put into page tables.
656          *
657          * The other side of the story is the pointer chasing in the page
658          * table walking code (when walking the page table without locking;
659          * ie. most of the time). Fortunately, these data accesses consist
660          * of a chain of data-dependent loads, meaning most CPUs (alpha
661          * being the notable exception) will already guarantee loads are
662          * seen in-order. See the alpha page table accessors for the
663          * smp_read_barrier_depends() barriers in page table walking code.
664          */
665         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
666 
667         ptl = pmd_lock(mm, pmd);
668         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
669                 mm_inc_nr_ptes(mm);
670                 pmd_populate(mm, pmd, new);
671                 new = NULL;
672         }
673         spin_unlock(ptl);
674         if (new)
675                 pte_free(mm, new);
676         return 0;
677 }
678 
679 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
680 {
681         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
682         if (!new)
683                 return -ENOMEM;
684 
685         smp_wmb(); /* See comment in __pte_alloc */
686 
687         spin_lock(&init_mm.page_table_lock);
688         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
689                 pmd_populate_kernel(&init_mm, pmd, new);
690                 new = NULL;
691         }
692         spin_unlock(&init_mm.page_table_lock);
693         if (new)
694                 pte_free_kernel(&init_mm, new);
695         return 0;
696 }
697 
698 static inline void init_rss_vec(int *rss)
699 {
700         memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
701 }
702 
703 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
704 {
705         int i;
706 
707         if (current->mm == mm)
708                 sync_mm_rss(mm);
709         for (i = 0; i < NR_MM_COUNTERS; i++)
710                 if (rss[i])
711                         add_mm_counter(mm, i, rss[i]);
712 }
713 
714 /*
715  * This function is called to print an error when a bad pte
716  * is found. For example, we might have a PFN-mapped pte in
717  * a region that doesn't allow it.
718  *
719  * The calling function must still handle the error.
720  */
721 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
722                           pte_t pte, struct page *page)
723 {
724         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
725         p4d_t *p4d = p4d_offset(pgd, addr);
726         pud_t *pud = pud_offset(p4d, addr);
727         pmd_t *pmd = pmd_offset(pud, addr);
728         struct address_space *mapping;
729         pgoff_t index;
730         static unsigned long resume;
731         static unsigned long nr_shown;
732         static unsigned long nr_unshown;
733 
734         /*
735          * Allow a burst of 60 reports, then keep quiet for that minute;
736          * or allow a steady drip of one report per second.
737          */
738         if (nr_shown == 60) {
739                 if (time_before(jiffies, resume)) {
740                         nr_unshown++;
741                         return;
742                 }
743                 if (nr_unshown) {
744                         pr_alert("BUG: Bad page map: %lu messages suppressed\n",
745                                  nr_unshown);
746                         nr_unshown = 0;
747                 }
748                 nr_shown = 0;
749         }
750         if (nr_shown++ == 0)
751                 resume = jiffies + 60 * HZ;
752 
753         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
754         index = linear_page_index(vma, addr);
755 
756         pr_alert("BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
757                  current->comm,
758                  (long long)pte_val(pte), (long long)pmd_val(*pmd));
759         if (page)
760                 dump_page(page, "bad pte");
761         pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
762                  (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
763         /*
764          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
765          */
766         pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
767                  vma->vm_file,
768                  vma->vm_ops ? vma->vm_ops->fault : NULL,
769                  vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
770                  mapping ? mapping->a_ops->readpage : NULL);
771         dump_stack();
772         add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
773 }
774 
775 /*
776  * vm_normal_page -- This function gets the "struct page" associated with a pte.
777  *
778  * "Special" mappings do not wish to be associated with a "struct page" (either
779  * it doesn't exist, or it exists but they don't want to touch it). In this
780  * case, NULL is returned here. "Normal" mappings do have a struct page.
781  *
782  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
783  * pte bit, in which case this function is trivial. Secondly, an architecture
784  * may not have a spare pte bit, which requires a more complicated scheme,
785  * described below.
786  *
787  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
788  * special mapping (even if there are underlying and valid "struct pages").
789  * COWed pages of a VM_PFNMAP are always normal.
790  *
791  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
792  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
793  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
794  * mapping will always honor the rule
795  *
796  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
797  *
798  * And for normal mappings this is false.
799  *
800  * This restricts such mappings to be a linear translation from virtual address
801  * to pfn. To get around this restriction, we allow arbitrary mappings so long
802  * as the vma is not a COW mapping; in that case, we know that all ptes are
803  * special (because none can have been COWed).
804  *
805  *
806  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
807  *
808  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
809  * page" backing, however the difference is that _all_ pages with a struct
810  * page (that is, those where pfn_valid is true) are refcounted and considered
811  * normal pages by the VM. The disadvantage is that pages are refcounted
812  * (which can be slower and simply not an option for some PFNMAP users). The
813  * advantage is that we don't have to follow the strict linearity rule of
814  * PFNMAP mappings in order to support COWable mappings.
815  *
816  */
817 #ifdef __HAVE_ARCH_PTE_SPECIAL
818 # define HAVE_PTE_SPECIAL 1
819 #else
820 # define HAVE_PTE_SPECIAL 0
821 #endif
822 struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
823                              pte_t pte, bool with_public_device)
824 {
825         unsigned long pfn = pte_pfn(pte);
826 
827         if (HAVE_PTE_SPECIAL) {
828                 if (likely(!pte_special(pte)))
829                         goto check_pfn;
830                 if (vma->vm_ops && vma->vm_ops->find_special_page)
831                         return vma->vm_ops->find_special_page(vma, addr);
832                 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
833                         return NULL;
834                 if (is_zero_pfn(pfn))
835                         return NULL;
836 
837                 /*
838                  * Device public pages are special pages (they are ZONE_DEVICE
839                  * pages but different from persistent memory). They behave
840                  * allmost like normal pages. The difference is that they are
841                  * not on the lru and thus should never be involve with any-
842                  * thing that involve lru manipulation (mlock, numa balancing,
843                  * ...).
844                  *
845                  * This is why we still want to return NULL for such page from
846                  * vm_normal_page() so that we do not have to special case all
847                  * call site of vm_normal_page().
848                  */
849                 if (likely(pfn <= highest_memmap_pfn)) {
850                         struct page *page = pfn_to_page(pfn);
851 
852                         if (is_device_public_page(page)) {
853                                 if (with_public_device)
854                                         return page;
855                                 return NULL;
856                         }
857                 }
858                 print_bad_pte(vma, addr, pte, NULL);
859                 return NULL;
860         }
861 
862         /* !HAVE_PTE_SPECIAL case follows: */
863 
864         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
865                 if (vma->vm_flags & VM_MIXEDMAP) {
866                         if (!pfn_valid(pfn))
867                                 return NULL;
868                         goto out;
869                 } else {
870                         unsigned long off;
871                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
872                         if (pfn == vma->vm_pgoff + off)
873                                 return NULL;
874                         if (!is_cow_mapping(vma->vm_flags))
875                                 return NULL;
876                 }
877         }
878 
879         if (is_zero_pfn(pfn))
880                 return NULL;
881 check_pfn:
882         if (unlikely(pfn > highest_memmap_pfn)) {
883                 print_bad_pte(vma, addr, pte, NULL);
884                 return NULL;
885         }
886 
887         /*
888          * NOTE! We still have PageReserved() pages in the page tables.
889          * eg. VDSO mappings can cause them to exist.
890          */
891 out:
892         return pfn_to_page(pfn);
893 }
894 
895 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
896 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
897                                 pmd_t pmd)
898 {
899         unsigned long pfn = pmd_pfn(pmd);
900 
901         /*
902          * There is no pmd_special() but there may be special pmds, e.g.
903          * in a direct-access (dax) mapping, so let's just replicate the
904          * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
905          */
906         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
907                 if (vma->vm_flags & VM_MIXEDMAP) {
908                         if (!pfn_valid(pfn))
909                                 return NULL;
910                         goto out;
911                 } else {
912                         unsigned long off;
913                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
914                         if (pfn == vma->vm_pgoff + off)
915                                 return NULL;
916                         if (!is_cow_mapping(vma->vm_flags))
917                                 return NULL;
918                 }
919         }
920 
921         if (is_zero_pfn(pfn))
922                 return NULL;
923         if (unlikely(pfn > highest_memmap_pfn))
924                 return NULL;
925 
926         /*
927          * NOTE! We still have PageReserved() pages in the page tables.
928          * eg. VDSO mappings can cause them to exist.
929          */
930 out:
931         return pfn_to_page(pfn);
932 }
933 #endif
934 
935 /*
936  * copy one vm_area from one task to the other. Assumes the page tables
937  * already present in the new task to be cleared in the whole range
938  * covered by this vma.
939  */
940 
941 static inline unsigned long
942 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
943                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
944                 unsigned long addr, int *rss)
945 {
946         unsigned long vm_flags = vma->vm_flags;
947         pte_t pte = *src_pte;
948         struct page *page;
949 
950         /* pte contains position in swap or file, so copy. */
951         if (unlikely(!pte_present(pte))) {
952                 swp_entry_t entry = pte_to_swp_entry(pte);
953 
954                 if (likely(!non_swap_entry(entry))) {
955                         if (swap_duplicate(entry) < 0)
956                                 return entry.val;
957 
958                         /* make sure dst_mm is on swapoff's mmlist. */
959                         if (unlikely(list_empty(&dst_mm->mmlist))) {
960                                 spin_lock(&mmlist_lock);
961                                 if (list_empty(&dst_mm->mmlist))
962                                         list_add(&dst_mm->mmlist,
963                                                         &src_mm->mmlist);
964                                 spin_unlock(&mmlist_lock);
965                         }
966                         rss[MM_SWAPENTS]++;
967                 } else if (is_migration_entry(entry)) {
968                         page = migration_entry_to_page(entry);
969 
970                         rss[mm_counter(page)]++;
971 
972                         if (is_write_migration_entry(entry) &&
973                                         is_cow_mapping(vm_flags)) {
974                                 /*
975                                  * COW mappings require pages in both
976                                  * parent and child to be set to read.
977                                  */
978                                 make_migration_entry_read(&entry);
979                                 pte = swp_entry_to_pte(entry);
980                                 if (pte_swp_soft_dirty(*src_pte))
981                                         pte = pte_swp_mksoft_dirty(pte);
982                                 set_pte_at(src_mm, addr, src_pte, pte);
983                         }
984                 } else if (is_device_private_entry(entry)) {
985                         page = device_private_entry_to_page(entry);
986 
987                         /*
988                          * Update rss count even for unaddressable pages, as
989                          * they should treated just like normal pages in this
990                          * respect.
991                          *
992                          * We will likely want to have some new rss counters
993                          * for unaddressable pages, at some point. But for now
994                          * keep things as they are.
995                          */
996                         get_page(page);
997                         rss[mm_counter(page)]++;
998                         page_dup_rmap(page, false);
999 
1000                         /*
1001                          * We do not preserve soft-dirty information, because so
1002                          * far, checkpoint/restore is the only feature that
1003                          * requires that. And checkpoint/restore does not work
1004                          * when a device driver is involved (you cannot easily
1005                          * save and restore device driver state).
1006                          */
1007                         if (is_write_device_private_entry(entry) &&
1008                             is_cow_mapping(vm_flags)) {
1009                                 make_device_private_entry_read(&entry);
1010                                 pte = swp_entry_to_pte(entry);
1011                                 set_pte_at(src_mm, addr, src_pte, pte);
1012                         }
1013                 }
1014                 goto out_set_pte;
1015         }
1016 
1017         /*
1018          * If it's a COW mapping, write protect it both
1019          * in the parent and the child
1020          */
1021         if (is_cow_mapping(vm_flags)) {
1022                 ptep_set_wrprotect(src_mm, addr, src_pte);
1023                 pte = pte_wrprotect(pte);
1024         }
1025 
1026         /*
1027          * If it's a shared mapping, mark it clean in
1028          * the child
1029          */
1030         if (vm_flags & VM_SHARED)
1031                 pte = pte_mkclean(pte);
1032         pte = pte_mkold(pte);
1033 
1034         page = vm_normal_page(vma, addr, pte);
1035         if (page) {
1036                 get_page(page);
1037                 page_dup_rmap(page, false);
1038                 rss[mm_counter(page)]++;
1039         } else if (pte_devmap(pte)) {
1040                 page = pte_page(pte);
1041 
1042                 /*
1043                  * Cache coherent device memory behave like regular page and
1044                  * not like persistent memory page. For more informations see
1045                  * MEMORY_DEVICE_CACHE_COHERENT in memory_hotplug.h
1046                  */
1047                 if (is_device_public_page(page)) {
1048                         get_page(page);
1049                         page_dup_rmap(page, false);
1050                         rss[mm_counter(page)]++;
1051                 }
1052         }
1053 
1054 out_set_pte:
1055         set_pte_at(dst_mm, addr, dst_pte, pte);
1056         return 0;
1057 }
1058 
1059 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1060                    pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
1061                    unsigned long addr, unsigned long end)
1062 {
1063         pte_t *orig_src_pte, *orig_dst_pte;
1064         pte_t *src_pte, *dst_pte;
1065         spinlock_t *src_ptl, *dst_ptl;
1066         int progress = 0;
1067         int rss[NR_MM_COUNTERS];
1068         swp_entry_t entry = (swp_entry_t){0};
1069 
1070 again:
1071         init_rss_vec(rss);
1072 
1073         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1074         if (!dst_pte)
1075                 return -ENOMEM;
1076         src_pte = pte_offset_map(src_pmd, addr);
1077         src_ptl = pte_lockptr(src_mm, src_pmd);
1078         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1079         orig_src_pte = src_pte;
1080         orig_dst_pte = dst_pte;
1081         arch_enter_lazy_mmu_mode();
1082 
1083         do {
1084                 /*
1085                  * We are holding two locks at this point - either of them
1086                  * could generate latencies in another task on another CPU.
1087                  */
1088                 if (progress >= 32) {
1089                         progress = 0;
1090                         if (need_resched() ||
1091                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1092                                 break;
1093                 }
1094                 if (pte_none(*src_pte)) {
1095                         progress++;
1096                         continue;
1097                 }
1098                 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
1099                                                         vma, addr, rss);
1100                 if (entry.val)
1101                         break;
1102                 progress += 8;
1103         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1104 
1105         arch_leave_lazy_mmu_mode();
1106         spin_unlock(src_ptl);
1107         pte_unmap(orig_src_pte);
1108         add_mm_rss_vec(dst_mm, rss);
1109         pte_unmap_unlock(orig_dst_pte, dst_ptl);
1110         cond_resched();
1111 
1112         if (entry.val) {
1113                 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
1114                         return -ENOMEM;
1115                 progress = 0;
1116         }
1117         if (addr != end)
1118                 goto again;
1119         return 0;
1120 }
1121 
1122 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1123                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
1124                 unsigned long addr, unsigned long end)
1125 {
1126         pmd_t *src_pmd, *dst_pmd;
1127         unsigned long next;
1128 
1129         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1130         if (!dst_pmd)
1131                 return -ENOMEM;
1132         src_pmd = pmd_offset(src_pud, addr);
1133         do {
1134                 next = pmd_addr_end(addr, end);
1135                 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1136                         || pmd_devmap(*src_pmd)) {
1137                         int err;
1138                         VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1139                         err = copy_huge_pmd(dst_mm, src_mm,
1140                                             dst_pmd, src_pmd, addr, vma);
1141                         if (err == -ENOMEM)
1142                                 return -ENOMEM;
1143                         if (!err)
1144                                 continue;
1145                         /* fall through */
1146                 }
1147                 if (pmd_none_or_clear_bad(src_pmd))
1148                         continue;
1149                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1150                                                 vma, addr, next))
1151                         return -ENOMEM;
1152         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1153         return 0;
1154 }
1155 
1156 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1157                 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
1158                 unsigned long addr, unsigned long end)
1159 {
1160         pud_t *src_pud, *dst_pud;
1161         unsigned long next;
1162 
1163         dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1164         if (!dst_pud)
1165                 return -ENOMEM;
1166         src_pud = pud_offset(src_p4d, addr);
1167         do {
1168                 next = pud_addr_end(addr, end);
1169                 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1170                         int err;
1171 
1172                         VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
1173                         err = copy_huge_pud(dst_mm, src_mm,
1174                                             dst_pud, src_pud, addr, vma);
1175                         if (err == -ENOMEM)
1176                                 return -ENOMEM;
1177                         if (!err)
1178                                 continue;
1179                         /* fall through */
1180                 }
1181                 if (pud_none_or_clear_bad(src_pud))
1182                         continue;
1183                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1184                                                 vma, addr, next))
1185                         return -ENOMEM;
1186         } while (dst_pud++, src_pud++, addr = next, addr != end);
1187         return 0;
1188 }
1189 
1190 static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1191                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1192                 unsigned long addr, unsigned long end)
1193 {
1194         p4d_t *src_p4d, *dst_p4d;
1195         unsigned long next;
1196 
1197         dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1198         if (!dst_p4d)
1199                 return -ENOMEM;
1200         src_p4d = p4d_offset(src_pgd, addr);
1201         do {
1202                 next = p4d_addr_end(addr, end);
1203                 if (p4d_none_or_clear_bad(src_p4d))
1204                         continue;
1205                 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
1206                                                 vma, addr, next))
1207                         return -ENOMEM;
1208         } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1209         return 0;
1210 }
1211 
1212 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1213                 struct vm_area_struct *vma)
1214 {
1215         pgd_t *src_pgd, *dst_pgd;
1216         unsigned long next;
1217         unsigned long addr = vma->vm_start;
1218         unsigned long end = vma->vm_end;
1219         unsigned long mmun_start;       /* For mmu_notifiers */
1220         unsigned long mmun_end;         /* For mmu_notifiers */
1221         bool is_cow;
1222         int ret;
1223 
1224         /*
1225          * Don't copy ptes where a page fault will fill them correctly.
1226          * Fork becomes much lighter when there are big shared or private
1227          * readonly mappings. The tradeoff is that copy_page_range is more
1228          * efficient than faulting.
1229          */
1230         if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1231                         !vma->anon_vma)
1232                 return 0;
1233 
1234         if (is_vm_hugetlb_page(vma))
1235                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1236 
1237         if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1238                 /*
1239                  * We do not free on error cases below as remove_vma
1240                  * gets called on error from higher level routine
1241                  */
1242                 ret = track_pfn_copy(vma);
1243                 if (ret)
1244                         return ret;
1245         }
1246 
1247         /*
1248          * We need to invalidate the secondary MMU mappings only when
1249          * there could be a permission downgrade on the ptes of the
1250          * parent mm. And a permission downgrade will only happen if
1251          * is_cow_mapping() returns true.
1252          */
1253         is_cow = is_cow_mapping(vma->vm_flags);
1254         mmun_start = addr;
1255         mmun_end   = end;
1256         if (is_cow)
1257                 mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1258                                                     mmun_end);
1259 
1260         ret = 0;
1261         dst_pgd = pgd_offset(dst_mm, addr);
1262         src_pgd = pgd_offset(src_mm, addr);
1263         do {
1264                 next = pgd_addr_end(addr, end);
1265                 if (pgd_none_or_clear_bad(src_pgd))
1266                         continue;
1267                 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
1268                                             vma, addr, next))) {
1269                         ret = -ENOMEM;
1270                         break;
1271                 }
1272         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1273 
1274         if (is_cow)
1275                 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1276         return ret;
1277 }
1278 
1279 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1280                                 struct vm_area_struct *vma, pmd_t *pmd,
1281                                 unsigned long addr, unsigned long end,
1282                                 struct zap_details *details)
1283 {
1284         struct mm_struct *mm = tlb->mm;
1285         int force_flush = 0;
1286         int rss[NR_MM_COUNTERS];
1287         spinlock_t *ptl;
1288         pte_t *start_pte;
1289         pte_t *pte;
1290         swp_entry_t entry;
1291 
1292         tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
1293 again:
1294         init_rss_vec(rss);
1295         start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1296         pte = start_pte;
1297         flush_tlb_batched_pending(mm);
1298         arch_enter_lazy_mmu_mode();
1299         do {
1300                 pte_t ptent = *pte;
1301                 if (pte_none(ptent))
1302                         continue;
1303 
1304                 if (pte_present(ptent)) {
1305                         struct page *page;
1306 
1307                         page = _vm_normal_page(vma, addr, ptent, true);
1308                         if (unlikely(details) && page) {
1309                                 /*
1310                                  * unmap_shared_mapping_pages() wants to
1311                                  * invalidate cache without truncating:
1312                                  * unmap shared but keep private pages.
1313                                  */
1314                                 if (details->check_mapping &&
1315                                     details->check_mapping != page_rmapping(page))
1316                                         continue;
1317                         }
1318                         ptent = ptep_get_and_clear_full(mm, addr, pte,
1319                                                         tlb->fullmm);
1320                         tlb_remove_tlb_entry(tlb, pte, addr);
1321                         if (unlikely(!page))
1322                                 continue;
1323 
1324                         if (!PageAnon(page)) {
1325                                 if (pte_dirty(ptent)) {
1326                                         force_flush = 1;
1327                                         set_page_dirty(page);
1328                                 }
1329                                 if (pte_young(ptent) &&
1330                                     likely(!(vma->vm_flags & VM_SEQ_READ)))
1331                                         mark_page_accessed(page);
1332                         }
1333                         rss[mm_counter(page)]--;
1334                         page_remove_rmap(page, false);
1335                         if (unlikely(page_mapcount(page) < 0))
1336                                 print_bad_pte(vma, addr, ptent, page);
1337                         if (unlikely(__tlb_remove_page(tlb, page))) {
1338                                 force_flush = 1;
1339                                 addr += PAGE_SIZE;
1340                                 break;
1341                         }
1342                         continue;
1343                 }
1344 
1345                 entry = pte_to_swp_entry(ptent);
1346                 if (non_swap_entry(entry) && is_device_private_entry(entry)) {
1347                         struct page *page = device_private_entry_to_page(entry);
1348 
1349                         if (unlikely(details && details->check_mapping)) {
1350                                 /*
1351                                  * unmap_shared_mapping_pages() wants to
1352                                  * invalidate cache without truncating:
1353                                  * unmap shared but keep private pages.
1354                                  */
1355                                 if (details->check_mapping !=
1356                                     page_rmapping(page))
1357                                         continue;
1358                         }
1359 
1360                         pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1361                         rss[mm_counter(page)]--;
1362                         page_remove_rmap(page, false);
1363                         put_page(page);
1364                         continue;
1365                 }
1366 
1367                 /* If details->check_mapping, we leave swap entries. */
1368                 if (unlikely(details))
1369                         continue;
1370 
1371                 entry = pte_to_swp_entry(ptent);
1372                 if (!non_swap_entry(entry))
1373                         rss[MM_SWAPENTS]--;
1374                 else if (is_migration_entry(entry)) {
1375                         struct page *page;
1376 
1377                         page = migration_entry_to_page(entry);
1378                         rss[mm_counter(page)]--;
1379                 }
1380                 if (unlikely(!free_swap_and_cache(entry)))
1381                         print_bad_pte(vma, addr, ptent, NULL);
1382                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1383         } while (pte++, addr += PAGE_SIZE, addr != end);
1384 
1385         add_mm_rss_vec(mm, rss);
1386         arch_leave_lazy_mmu_mode();
1387 
1388         /* Do the actual TLB flush before dropping ptl */
1389         if (force_flush)
1390                 tlb_flush_mmu_tlbonly(tlb);
1391         pte_unmap_unlock(start_pte, ptl);
1392 
1393         /*
1394          * If we forced a TLB flush (either due to running out of
1395          * batch buffers or because we needed to flush dirty TLB
1396          * entries before releasing the ptl), free the batched
1397          * memory too. Restart if we didn't do everything.
1398          */
1399         if (force_flush) {
1400                 force_flush = 0;
1401                 tlb_flush_mmu_free(tlb);
1402                 if (addr != end)
1403                         goto again;
1404         }
1405 
1406         return addr;
1407 }
1408 
1409 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1410                                 struct vm_area_struct *vma, pud_t *pud,
1411                                 unsigned long addr, unsigned long end,
1412                                 struct zap_details *details)
1413 {
1414         pmd_t *pmd;
1415         unsigned long next;
1416 
1417         pmd = pmd_offset(pud, addr);
1418         do {
1419                 next = pmd_addr_end(addr, end);
1420                 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1421                         if (next - addr != HPAGE_PMD_SIZE) {
1422                                 VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
1423                                     !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1424                                 __split_huge_pmd(vma, pmd, addr, false, NULL);
1425                         } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1426                                 goto next;
1427                         /* fall through */
1428                 }
1429                 /*
1430                  * Here there can be other concurrent MADV_DONTNEED or
1431                  * trans huge page faults running, and if the pmd is
1432                  * none or trans huge it can change under us. This is
1433                  * because MADV_DONTNEED holds the mmap_sem in read
1434                  * mode.
1435                  */
1436                 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1437                         goto next;
1438                 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1439 next:
1440                 cond_resched();
1441         } while (pmd++, addr = next, addr != end);
1442 
1443         return addr;
1444 }
1445 
1446 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1447                                 struct vm_area_struct *vma, p4d_t *p4d,
1448                                 unsigned long addr, unsigned long end,
1449                                 struct zap_details *details)
1450 {
1451         pud_t *pud;
1452         unsigned long next;
1453 
1454         pud = pud_offset(p4d, addr);
1455         do {
1456                 next = pud_addr_end(addr, end);
1457                 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1458                         if (next - addr != HPAGE_PUD_SIZE) {
1459                                 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1460                                 split_huge_pud(vma, pud, addr);
1461                         } else if (zap_huge_pud(tlb, vma, pud, addr))
1462                                 goto next;
1463                         /* fall through */
1464                 }
1465                 if (pud_none_or_clear_bad(pud))
1466                         continue;
1467                 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1468 next:
1469                 cond_resched();
1470         } while (pud++, addr = next, addr != end);
1471 
1472         return addr;
1473 }
1474 
1475 static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1476                                 struct vm_area_struct *vma, pgd_t *pgd,
1477                                 unsigned long addr, unsigned long end,
1478                                 struct zap_details *details)
1479 {
1480         p4d_t *p4d;
1481         unsigned long next;
1482 
1483         p4d = p4d_offset(pgd, addr);
1484         do {
1485                 next = p4d_addr_end(addr, end);
1486                 if (p4d_none_or_clear_bad(p4d))
1487                         continue;
1488                 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1489         } while (p4d++, addr = next, addr != end);
1490 
1491         return addr;
1492 }
1493 
1494 void unmap_page_range(struct mmu_gather *tlb,
1495                              struct vm_area_struct *vma,
1496                              unsigned long addr, unsigned long end,
1497                              struct zap_details *details)
1498 {
1499         pgd_t *pgd;
1500         unsigned long next;
1501 
1502         BUG_ON(addr >= end);
1503         tlb_start_vma(tlb, vma);
1504         pgd = pgd_offset(vma->vm_mm, addr);
1505         do {
1506                 next = pgd_addr_end(addr, end);
1507                 if (pgd_none_or_clear_bad(pgd))
1508                         continue;
1509                 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1510         } while (pgd++, addr = next, addr != end);
1511         tlb_end_vma(tlb, vma);
1512 }
1513 
1514 
1515 static void unmap_single_vma(struct mmu_gather *tlb,
1516                 struct vm_area_struct *vma, unsigned long start_addr,
1517                 unsigned long end_addr,
1518                 struct zap_details *details)
1519 {
1520         unsigned long start = max(vma->vm_start, start_addr);
1521         unsigned long end;
1522 
1523         if (start >= vma->vm_end)
1524                 return;
1525         end = min(vma->vm_end, end_addr);
1526         if (end <= vma->vm_start)
1527                 return;
1528 
1529         if (vma->vm_file)
1530                 uprobe_munmap(vma, start, end);
1531 
1532         if (unlikely(vma->vm_flags & VM_PFNMAP))
1533                 untrack_pfn(vma, 0, 0);
1534 
1535         if (start != end) {
1536                 if (unlikely(is_vm_hugetlb_page(vma))) {
1537                         /*
1538                          * It is undesirable to test vma->vm_file as it
1539                          * should be non-null for valid hugetlb area.
1540                          * However, vm_file will be NULL in the error
1541                          * cleanup path of mmap_region. When
1542                          * hugetlbfs ->mmap method fails,
1543                          * mmap_region() nullifies vma->vm_file
1544                          * before calling this function to clean up.
1545                          * Since no pte has actually been setup, it is
1546                          * safe to do nothing in this case.
1547                          */
1548                         if (vma->vm_file) {
1549                                 i_mmap_lock_write(vma->vm_file->f_mapping);
1550                                 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1551                                 i_mmap_unlock_write(vma->vm_file->f_mapping);
1552                         }
1553                 } else
1554                         unmap_page_range(tlb, vma, start, end, details);
1555         }
1556 }
1557 
1558 /**
1559  * unmap_vmas - unmap a range of memory covered by a list of vma's
1560  * @tlb: address of the caller's struct mmu_gather
1561  * @vma: the starting vma
1562  * @start_addr: virtual address at which to start unmapping
1563  * @end_addr: virtual address at which to end unmapping
1564  *
1565  * Unmap all pages in the vma list.
1566  *
1567  * Only addresses between `start' and `end' will be unmapped.
1568  *
1569  * The VMA list must be sorted in ascending virtual address order.
1570  *
1571  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1572  * range after unmap_vmas() returns.  So the only responsibility here is to
1573  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1574  * drops the lock and schedules.
1575  */
1576 void unmap_vmas(struct mmu_gather *tlb,
1577                 struct vm_area_struct *vma, unsigned long start_addr,
1578                 unsigned long end_addr)
1579 {
1580         struct mm_struct *mm = vma->vm_mm;
1581 
1582         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1583         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1584                 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1585         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1586 }
1587 
1588 /**
1589  * zap_page_range - remove user pages in a given range
1590  * @vma: vm_area_struct holding the applicable pages
1591  * @start: starting address of pages to zap
1592  * @size: number of bytes to zap
1593  *
1594  * Caller must protect the VMA list
1595  */
1596 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1597                 unsigned long size)
1598 {
1599         struct mm_struct *mm = vma->vm_mm;
1600         struct mmu_gather tlb;
1601         unsigned long end = start + size;
1602 
1603         lru_add_drain();
1604         tlb_gather_mmu(&tlb, mm, start, end);
1605         update_hiwater_rss(mm);
1606         mmu_notifier_invalidate_range_start(mm, start, end);
1607         for ( ; vma && vma->vm_start < end; vma = vma->vm_next) {
1608                 unmap_single_vma(&tlb, vma, start, end, NULL);
1609 
1610                 /*
1611                  * zap_page_range does not specify whether mmap_sem should be
1612                  * held for read or write. That allows parallel zap_page_range
1613                  * operations to unmap a PTE and defer a flush meaning that
1614                  * this call observes pte_none and fails to flush the TLB.
1615                  * Rather than adding a complex API, ensure that no stale
1616                  * TLB entries exist when this call returns.
1617                  */
1618                 flush_tlb_range(vma, start, end);
1619         }
1620 
1621         mmu_notifier_invalidate_range_end(mm, start, end);
1622         tlb_finish_mmu(&tlb, start, end);
1623 }
1624 
1625 /**
1626  * zap_page_range_single - remove user pages in a given range
1627  * @vma: vm_area_struct holding the applicable pages
1628  * @address: starting address of pages to zap
1629  * @size: number of bytes to zap
1630  * @details: details of shared cache invalidation
1631  *
1632  * The range must fit into one VMA.
1633  */
1634 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1635                 unsigned long size, struct zap_details *details)
1636 {
1637         struct mm_struct *mm = vma->vm_mm;
1638         struct mmu_gather tlb;
1639         unsigned long end = address + size;
1640 
1641         lru_add_drain();
1642         tlb_gather_mmu(&tlb, mm, address, end);
1643         update_hiwater_rss(mm);
1644         mmu_notifier_invalidate_range_start(mm, address, end);
1645         unmap_single_vma(&tlb, vma, address, end, details);
1646         mmu_notifier_invalidate_range_end(mm, address, end);
1647         tlb_finish_mmu(&tlb, address, end);
1648 }
1649 
1650 /**
1651  * zap_vma_ptes - remove ptes mapping the vma
1652  * @vma: vm_area_struct holding ptes to be zapped
1653  * @address: starting address of pages to zap
1654  * @size: number of bytes to zap
1655  *
1656  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1657  *
1658  * The entire address range must be fully contained within the vma.
1659  *
1660  * Returns 0 if successful.
1661  */
1662 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1663                 unsigned long size)
1664 {
1665         if (address < vma->vm_start || address + size > vma->vm_end ||
1666                         !(vma->vm_flags & VM_PFNMAP))
1667                 return -1;
1668         zap_page_range_single(vma, address, size, NULL);
1669         return 0;
1670 }
1671 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1672 
1673 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1674                         spinlock_t **ptl)
1675 {
1676         pgd_t *pgd;
1677         p4d_t *p4d;
1678         pud_t *pud;
1679         pmd_t *pmd;
1680 
1681         pgd = pgd_offset(mm, addr);
1682         p4d = p4d_alloc(mm, pgd, addr);
1683         if (!p4d)
1684                 return NULL;
1685         pud = pud_alloc(mm, p4d, addr);
1686         if (!pud)
1687                 return NULL;
1688         pmd = pmd_alloc(mm, pud, addr);
1689         if (!pmd)
1690                 return NULL;
1691 
1692         VM_BUG_ON(pmd_trans_huge(*pmd));
1693         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1694 }
1695 
1696 /*
1697  * This is the old fallback for page remapping.
1698  *
1699  * For historical reasons, it only allows reserved pages. Only
1700  * old drivers should use this, and they needed to mark their
1701  * pages reserved for the old functions anyway.
1702  */
1703 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1704                         struct page *page, pgprot_t prot)
1705 {
1706         struct mm_struct *mm = vma->vm_mm;
1707         int retval;
1708         pte_t *pte;
1709         spinlock_t *ptl;
1710 
1711         retval = -EINVAL;
1712         if (PageAnon(page))
1713                 goto out;
1714         retval = -ENOMEM;
1715         flush_dcache_page(page);
1716         pte = get_locked_pte(mm, addr, &ptl);
1717         if (!pte)
1718                 goto out;
1719         retval = -EBUSY;
1720         if (!pte_none(*pte))
1721                 goto out_unlock;
1722 
1723         /* Ok, finally just insert the thing.. */
1724         get_page(page);
1725         inc_mm_counter_fast(mm, mm_counter_file(page));
1726         page_add_file_rmap(page, false);
1727         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1728 
1729         retval = 0;
1730         pte_unmap_unlock(pte, ptl);
1731         return retval;
1732 out_unlock:
1733         pte_unmap_unlock(pte, ptl);
1734 out:
1735         return retval;
1736 }
1737 
1738 /**
1739  * vm_insert_page - insert single page into user vma
1740  * @vma: user vma to map to
1741  * @addr: target user address of this page
1742  * @page: source kernel page
1743  *
1744  * This allows drivers to insert individual pages they've allocated
1745  * into a user vma.
1746  *
1747  * The page has to be a nice clean _individual_ kernel allocation.
1748  * If you allocate a compound page, you need to have marked it as
1749  * such (__GFP_COMP), or manually just split the page up yourself
1750  * (see split_page()).
1751  *
1752  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1753  * took an arbitrary page protection parameter. This doesn't allow
1754  * that. Your vma protection will have to be set up correctly, which
1755  * means that if you want a shared writable mapping, you'd better
1756  * ask for a shared writable mapping!
1757  *
1758  * The page does not need to be reserved.
1759  *
1760  * Usually this function is called from f_op->mmap() handler
1761  * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1762  * Caller must set VM_MIXEDMAP on vma if it wants to call this
1763  * function from other places, for example from page-fault handler.
1764  */
1765 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1766                         struct page *page)
1767 {
1768         if (addr < vma->vm_start || addr >= vma->vm_end)
1769                 return -EFAULT;
1770         if (!page_count(page))
1771                 return -EINVAL;
1772         if (!(vma->vm_flags & VM_MIXEDMAP)) {
1773                 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1774                 BUG_ON(vma->vm_flags & VM_PFNMAP);
1775                 vma->vm_flags |= VM_MIXEDMAP;
1776         }
1777         return insert_page(vma, addr, page, vma->vm_page_prot);
1778 }
1779 EXPORT_SYMBOL(vm_insert_page);
1780 
1781 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1782                         pfn_t pfn, pgprot_t prot, bool mkwrite)
1783 {
1784         struct mm_struct *mm = vma->vm_mm;
1785         int retval;
1786         pte_t *pte, entry;
1787         spinlock_t *ptl;
1788 
1789         retval = -ENOMEM;
1790         pte = get_locked_pte(mm, addr, &ptl);
1791         if (!pte)
1792                 goto out;
1793         retval = -EBUSY;
1794         if (!pte_none(*pte)) {
1795                 if (mkwrite) {
1796                         /*
1797                          * For read faults on private mappings the PFN passed
1798                          * in may not match the PFN we have mapped if the
1799                          * mapped PFN is a writeable COW page.  In the mkwrite
1800                          * case we are creating a writable PTE for a shared
1801                          * mapping and we expect the PFNs to match.
1802                          */
1803                         if (WARN_ON_ONCE(pte_pfn(*pte) != pfn_t_to_pfn(pfn)))
1804                                 goto out_unlock;
1805                         entry = *pte;
1806                         goto out_mkwrite;
1807                 } else
1808                         goto out_unlock;
1809         }
1810 
1811         /* Ok, finally just insert the thing.. */
1812         if (pfn_t_devmap(pfn))
1813                 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1814         else
1815                 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1816 
1817 out_mkwrite:
1818         if (mkwrite) {
1819                 entry = pte_mkyoung(entry);
1820                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1821         }
1822 
1823         set_pte_at(mm, addr, pte, entry);
1824         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1825 
1826         retval = 0;
1827 out_unlock:
1828         pte_unmap_unlock(pte, ptl);
1829 out:
1830         return retval;
1831 }
1832 
1833 /**
1834  * vm_insert_pfn - insert single pfn into user vma
1835  * @vma: user vma to map to
1836  * @addr: target user address of this page
1837  * @pfn: source kernel pfn
1838  *
1839  * Similar to vm_insert_page, this allows drivers to insert individual pages
1840  * they've allocated into a user vma. Same comments apply.
1841  *
1842  * This function should only be called from a vm_ops->fault handler, and
1843  * in that case the handler should return NULL.
1844  *
1845  * vma cannot be a COW mapping.
1846  *
1847  * As this is called only for pages that do not currently exist, we
1848  * do not need to flush old virtual caches or the TLB.
1849  */
1850 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1851                         unsigned long pfn)
1852 {
1853         return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1854 }
1855 EXPORT_SYMBOL(vm_insert_pfn);
1856 
1857 /**
1858  * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1859  * @vma: user vma to map to
1860  * @addr: target user address of this page
1861  * @pfn: source kernel pfn
1862  * @pgprot: pgprot flags for the inserted page
1863  *
1864  * This is exactly like vm_insert_pfn, except that it allows drivers to
1865  * to override pgprot on a per-page basis.
1866  *
1867  * This only makes sense for IO mappings, and it makes no sense for
1868  * cow mappings.  In general, using multiple vmas is preferable;
1869  * vm_insert_pfn_prot should only be used if using multiple VMAs is
1870  * impractical.
1871  */
1872 int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1873                         unsigned long pfn, pgprot_t pgprot)
1874 {
1875         int ret;
1876         /*
1877          * Technically, architectures with pte_special can avoid all these
1878          * restrictions (same for remap_pfn_range).  However we would like
1879          * consistency in testing and feature parity among all, so we should
1880          * try to keep these invariants in place for everybody.
1881          */
1882         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1883         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1884                                                 (VM_PFNMAP|VM_MIXEDMAP));
1885         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1886         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1887 
1888         if (addr < vma->vm_start || addr >= vma->vm_end)
1889                 return -EFAULT;
1890 
1891         track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1892 
1893         ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
1894                         false);
1895 
1896         return ret;
1897 }
1898 EXPORT_SYMBOL(vm_insert_pfn_prot);
1899 
1900 static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1901                         pfn_t pfn, bool mkwrite)
1902 {
1903         pgprot_t pgprot = vma->vm_page_prot;
1904 
1905         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1906 
1907         if (addr < vma->vm_start || addr >= vma->vm_end)
1908                 return -EFAULT;
1909 
1910         track_pfn_insert(vma, &pgprot, pfn);
1911 
1912         /*
1913          * If we don't have pte special, then we have to use the pfn_valid()
1914          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1915          * refcount the page if pfn_valid is true (hence insert_page rather
1916          * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
1917          * without pte special, it would there be refcounted as a normal page.
1918          */
1919         if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1920                 struct page *page;
1921 
1922                 /*
1923                  * At this point we are committed to insert_page()
1924                  * regardless of whether the caller specified flags that
1925                  * result in pfn_t_has_page() == false.
1926                  */
1927                 page = pfn_to_page(pfn_t_to_pfn(pfn));
1928                 return insert_page(vma, addr, page, pgprot);
1929         }
1930         return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
1931 }
1932 
1933 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1934                         pfn_t pfn)
1935 {
1936         return __vm_insert_mixed(vma, addr, pfn, false);
1937 
1938 }
1939 EXPORT_SYMBOL(vm_insert_mixed);
1940 
1941 int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr,
1942                         pfn_t pfn)
1943 {
1944         return __vm_insert_mixed(vma, addr, pfn, true);
1945 }
1946 EXPORT_SYMBOL(vm_insert_mixed_mkwrite);
1947 
1948 /*
1949  * maps a range of physical memory into the requested pages. the old
1950  * mappings are removed. any references to nonexistent pages results
1951  * in null mappings (currently treated as "copy-on-access")
1952  */
1953 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1954                         unsigned long addr, unsigned long end,
1955                         unsigned long pfn, pgprot_t prot)
1956 {
1957         pte_t *pte;
1958         spinlock_t *ptl;
1959 
1960         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1961         if (!pte)
1962                 return -ENOMEM;
1963         arch_enter_lazy_mmu_mode();
1964         do {
1965                 BUG_ON(!pte_none(*pte));
1966                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1967                 pfn++;
1968         } while (pte++, addr += PAGE_SIZE, addr != end);
1969         arch_leave_lazy_mmu_mode();
1970         pte_unmap_unlock(pte - 1, ptl);
1971         return 0;
1972 }
1973 
1974 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1975                         unsigned long addr, unsigned long end,
1976                         unsigned long pfn, pgprot_t prot)
1977 {
1978         pmd_t *pmd;
1979         unsigned long next;
1980 
1981         pfn -= addr >> PAGE_SHIFT;
1982         pmd = pmd_alloc(mm, pud, addr);
1983         if (!pmd)
1984                 return -ENOMEM;
1985         VM_BUG_ON(pmd_trans_huge(*pmd));
1986         do {
1987                 next = pmd_addr_end(addr, end);
1988                 if (remap_pte_range(mm, pmd, addr, next,
1989                                 pfn + (addr >> PAGE_SHIFT), prot))
1990                         return -ENOMEM;
1991         } while (pmd++, addr = next, addr != end);
1992         return 0;
1993 }
1994 
1995 static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
1996                         unsigned long addr, unsigned long end,
1997                         unsigned long pfn, pgprot_t prot)
1998 {
1999         pud_t *pud;
2000         unsigned long next;
2001 
2002         pfn -= addr >> PAGE_SHIFT;
2003         pud = pud_alloc(mm, p4d, addr);
2004         if (!pud)
2005                 return -ENOMEM;
2006         do {
2007                 next = pud_addr_end(addr, end);
2008                 if (remap_pmd_range(mm, pud, addr, next,
2009                                 pfn + (addr >> PAGE_SHIFT), prot))
2010                         return -ENOMEM;
2011         } while (pud++, addr = next, addr != end);
2012         return 0;
2013 }
2014 
2015 static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2016                         unsigned long addr, unsigned long end,
2017                         unsigned long pfn, pgprot_t prot)
2018 {
2019         p4d_t *p4d;
2020         unsigned long next;
2021 
2022         pfn -= addr >> PAGE_SHIFT;
2023         p4d = p4d_alloc(mm, pgd, addr);
2024         if (!p4d)
2025                 return -ENOMEM;
2026         do {
2027                 next = p4d_addr_end(addr, end);
2028                 if (remap_pud_range(mm, p4d, addr, next,
2029                                 pfn + (addr >> PAGE_SHIFT), prot))
2030                         return -ENOMEM;
2031         } while (p4d++, addr = next, addr != end);
2032         return 0;
2033 }
2034 
2035 /**
2036  * remap_pfn_range - remap kernel memory to userspace
2037  * @vma: user vma to map to
2038  * @addr: target user address to start at
2039  * @pfn: physical address of kernel memory
2040  * @size: size of map area
2041  * @prot: page protection flags for this mapping
2042  *
2043  *  Note: this is only safe if the mm semaphore is held when called.
2044  */
2045 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2046                     unsigned long pfn, unsigned long size, pgprot_t prot)
2047 {
2048         pgd_t *pgd;
2049         unsigned long next;
2050         unsigned long end = addr + PAGE_ALIGN(size);
2051         struct mm_struct *mm = vma->vm_mm;
2052         unsigned long remap_pfn = pfn;
2053         int err;
2054 
2055         /*
2056          * Physically remapped pages are special. Tell the
2057          * rest of the world about it:
2058          *   VM_IO tells people not to look at these pages
2059          *      (accesses can have side effects).
2060          *   VM_PFNMAP tells the core MM that the base pages are just
2061          *      raw PFN mappings, and do not have a "struct page" associated
2062          *      with them.
2063          *   VM_DONTEXPAND
2064          *      Disable vma merging and expanding with mremap().
2065          *   VM_DONTDUMP
2066          *      Omit vma from core dump, even when VM_IO turned off.
2067          *
2068          * There's a horrible special case to handle copy-on-write
2069          * behaviour that some programs depend on. We mark the "original"
2070          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2071          * See vm_normal_page() for details.
2072          */
2073         if (is_cow_mapping(vma->vm_flags)) {
2074                 if (addr != vma->vm_start || end != vma->vm_end)
2075                         return -EINVAL;
2076                 vma->vm_pgoff = pfn;
2077         }
2078 
2079         err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
2080         if (err)
2081                 return -EINVAL;
2082 
2083         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2084 
2085         BUG_ON(addr >= end);
2086         pfn -= addr >> PAGE_SHIFT;
2087         pgd = pgd_offset(mm, addr);
2088         flush_cache_range(vma, addr, end);
2089         do {
2090                 next = pgd_addr_end(addr, end);
2091                 err = remap_p4d_range(mm, pgd, addr, next,
2092                                 pfn + (addr >> PAGE_SHIFT), prot);
2093                 if (err)
2094                         break;
2095         } while (pgd++, addr = next, addr != end);
2096 
2097         if (err)
2098                 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
2099 
2100         return err;
2101 }
2102 EXPORT_SYMBOL(remap_pfn_range);
2103 
2104 /**
2105  * vm_iomap_memory - remap memory to userspace
2106  * @vma: user vma to map to
2107  * @start: start of area
2108  * @len: size of area
2109  *
2110  * This is a simplified io_remap_pfn_range() for common driver use. The
2111  * driver just needs to give us the physical memory range to be mapped,
2112  * we'll figure out the rest from the vma information.
2113  *
2114  * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2115  * whatever write-combining details or similar.
2116  */
2117 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2118 {
2119         unsigned long vm_len, pfn, pages;
2120 
2121         /* Check that the physical memory area passed in looks valid */
2122         if (start + len < start)
2123                 return -EINVAL;
2124         /*
2125          * You *really* shouldn't map things that aren't page-aligned,
2126          * but we've historically allowed it because IO memory might
2127          * just have smaller alignment.
2128          */
2129         len += start & ~PAGE_MASK;
2130         pfn = start >> PAGE_SHIFT;
2131         pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2132         if (pfn + pages < pfn)
2133                 return -EINVAL;
2134 
2135         /* We start the mapping 'vm_pgoff' pages into the area */
2136         if (vma->vm_pgoff > pages)
2137                 return -EINVAL;
2138         pfn += vma->vm_pgoff;
2139         pages -= vma->vm_pgoff;
2140 
2141         /* Can we fit all of the mapping? */
2142         vm_len = vma->vm_end - vma->vm_start;
2143         if (vm_len >> PAGE_SHIFT > pages)
2144                 return -EINVAL;
2145 
2146         /* Ok, let it rip */
2147         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2148 }
2149 EXPORT_SYMBOL(vm_iomap_memory);
2150 
2151 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2152                                      unsigned long addr, unsigned long end,
2153                                      pte_fn_t fn, void *data)
2154 {
2155         pte_t *pte;
2156         int err;
2157         pgtable_t token;
2158         spinlock_t *uninitialized_var(ptl);
2159 
2160         pte = (mm == &init_mm) ?
2161                 pte_alloc_kernel(pmd, addr) :
2162                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2163         if (!pte)
2164                 return -ENOMEM;
2165 
2166         BUG_ON(pmd_huge(*pmd));
2167 
2168         arch_enter_lazy_mmu_mode();
2169 
2170         token = pmd_pgtable(*pmd);
2171 
2172         do {
2173                 err = fn(pte++, token, addr, data);
2174                 if (err)
2175                         break;
2176         } while (addr += PAGE_SIZE, addr != end);
2177 
2178         arch_leave_lazy_mmu_mode();
2179 
2180         if (mm != &init_mm)
2181                 pte_unmap_unlock(pte-1, ptl);
2182         return err;
2183 }
2184 
2185 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2186                                      unsigned long addr, unsigned long end,
2187                                      pte_fn_t fn, void *data)
2188 {
2189         pmd_t *pmd;
2190         unsigned long next;
2191         int err;
2192 
2193         BUG_ON(pud_huge(*pud));
2194 
2195         pmd = pmd_alloc(mm, pud, addr);
2196         if (!pmd)
2197                 return -ENOMEM;
2198         do {
2199                 next = pmd_addr_end(addr, end);
2200                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2201                 if (err)
2202                         break;
2203         } while (pmd++, addr = next, addr != end);
2204         return err;
2205 }
2206 
2207 static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2208                                      unsigned long addr, unsigned long end,
2209                                      pte_fn_t fn, void *data)
2210 {
2211         pud_t *pud;
2212         unsigned long next;
2213         int err;
2214 
2215         pud = pud_alloc(mm, p4d, addr);
2216         if (!pud)
2217                 return -ENOMEM;
2218         do {
2219                 next = pud_addr_end(addr, end);
2220                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2221                 if (err)
2222                         break;
2223         } while (pud++, addr = next, addr != end);
2224         return err;
2225 }
2226 
2227 static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2228                                      unsigned long addr, unsigned long end,
2229                                      pte_fn_t fn, void *data)
2230 {
2231         p4d_t *p4d;
2232         unsigned long next;
2233         int err;
2234 
2235         p4d = p4d_alloc(mm, pgd, addr);
2236         if (!p4d)
2237                 return -ENOMEM;
2238         do {
2239                 next = p4d_addr_end(addr, end);
2240                 err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
2241                 if (err)
2242                         break;
2243         } while (p4d++, addr = next, addr != end);
2244         return err;
2245 }
2246 
2247 /*
2248  * Scan a region of virtual memory, filling in page tables as necessary
2249  * and calling a provided function on each leaf page table.
2250  */
2251 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2252                         unsigned long size, pte_fn_t fn, void *data)
2253 {
2254         pgd_t *pgd;
2255         unsigned long next;
2256         unsigned long end = addr + size;
2257         int err;
2258 
2259         if (WARN_ON(addr >= end))
2260                 return -EINVAL;
2261 
2262         pgd = pgd_offset(mm, addr);
2263         do {
2264                 next = pgd_addr_end(addr, end);
2265                 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
2266                 if (err)
2267                         break;
2268         } while (pgd++, addr = next, addr != end);
2269 
2270         return err;
2271 }
2272 EXPORT_SYMBOL_GPL(apply_to_page_range);
2273 
2274 /*
2275  * handle_pte_fault chooses page fault handler according to an entry which was
2276  * read non-atomically.  Before making any commitment, on those architectures
2277  * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2278  * parts, do_swap_page must check under lock before unmapping the pte and
2279  * proceeding (but do_wp_page is only called after already making such a check;
2280  * and do_anonymous_page can safely check later on).
2281  */
2282 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2283                                 pte_t *page_table, pte_t orig_pte)
2284 {
2285         int same = 1;
2286 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2287         if (sizeof(pte_t) > sizeof(unsigned long)) {
2288                 spinlock_t *ptl = pte_lockptr(mm, pmd);
2289                 spin_lock(ptl);
2290                 same = pte_same(*page_table, orig_pte);
2291                 spin_unlock(ptl);
2292         }
2293 #endif
2294         pte_unmap(page_table);
2295         return same;
2296 }
2297 
2298 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2299 {
2300         debug_dma_assert_idle(src);
2301 
2302         /*
2303          * If the source page was a PFN mapping, we don't have
2304          * a "struct page" for it. We do a best-effort copy by
2305          * just copying from the original user address. If that
2306          * fails, we just zero-fill it. Live with it.
2307          */
2308         if (unlikely(!src)) {
2309                 void *kaddr = kmap_atomic(dst);
2310                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2311 
2312                 /*
2313                  * This really shouldn't fail, because the page is there
2314                  * in the page tables. But it might just be unreadable,
2315                  * in which case we just give up and fill the result with
2316                  * zeroes.
2317                  */
2318                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2319                         clear_page(kaddr);
2320                 kunmap_atomic(kaddr);
2321                 flush_dcache_page(dst);
2322         } else
2323                 copy_user_highpage(dst, src, va, vma);
2324 }
2325 
2326 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2327 {
2328         struct file *vm_file = vma->vm_file;
2329 
2330         if (vm_file)
2331                 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2332 
2333         /*
2334          * Special mappings (e.g. VDSO) do not have any file so fake
2335          * a default GFP_KERNEL for them.
2336          */
2337         return GFP_KERNEL;
2338 }
2339 
2340 /*
2341  * Notify the address space that the page is about to become writable so that
2342  * it can prohibit this or wait for the page to get into an appropriate state.
2343  *
2344  * We do this without the lock held, so that it can sleep if it needs to.
2345  */
2346 static int do_page_mkwrite(struct vm_fault *vmf)
2347 {
2348         int ret;
2349         struct page *page = vmf->page;
2350         unsigned int old_flags = vmf->flags;
2351 
2352         vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2353 
2354         ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2355         /* Restore original flags so that caller is not surprised */
2356         vmf->flags = old_flags;
2357         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2358                 return ret;
2359         if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2360                 lock_page(page);
2361                 if (!page->mapping) {
2362                         unlock_page(page);
2363                         return 0; /* retry */
2364                 }
2365                 ret |= VM_FAULT_LOCKED;
2366         } else
2367                 VM_BUG_ON_PAGE(!PageLocked(page), page);
2368         return ret;
2369 }
2370 
2371 /*
2372  * Handle dirtying of a page in shared file mapping on a write fault.
2373  *
2374  * The function expects the page to be locked and unlocks it.
2375  */
2376 static void fault_dirty_shared_page(struct vm_area_struct *vma,
2377                                     struct page *page)
2378 {
2379         struct address_space *mapping;
2380         bool dirtied;
2381         bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2382 
2383         dirtied = set_page_dirty(page);
2384         VM_BUG_ON_PAGE(PageAnon(page), page);
2385         /*
2386          * Take a local copy of the address_space - page.mapping may be zeroed
2387          * by truncate after unlock_page().   The address_space itself remains
2388          * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
2389          * release semantics to prevent the compiler from undoing this copying.
2390          */
2391         mapping = page_rmapping(page);
2392         unlock_page(page);
2393 
2394         if ((dirtied || page_mkwrite) && mapping) {
2395                 /*
2396                  * Some device drivers do not set page.mapping
2397                  * but still dirty their pages
2398                  */
2399                 balance_dirty_pages_ratelimited(mapping);
2400         }
2401 
2402         if (!page_mkwrite)
2403                 file_update_time(vma->vm_file);
2404 }
2405 
2406 /*
2407  * Handle write page faults for pages that can be reused in the current vma
2408  *
2409  * This can happen either due to the mapping being with the VM_SHARED flag,
2410  * or due to us being the last reference standing to the page. In either
2411  * case, all we need to do here is to mark the page as writable and update
2412  * any related book-keeping.
2413  */
2414 static inline void wp_page_reuse(struct vm_fault *vmf)
2415         __releases(vmf->ptl)
2416 {
2417         struct vm_area_struct *vma = vmf->vma;
2418         struct page *page = vmf->page;
2419         pte_t entry;
2420         /*
2421          * Clear the pages cpupid information as the existing
2422          * information potentially belongs to a now completely
2423          * unrelated process.
2424          */
2425         if (page)
2426                 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2427 
2428         flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2429         entry = pte_mkyoung(vmf->orig_pte);
2430         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2431         if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2432                 update_mmu_cache(vma, vmf->address, vmf->pte);
2433         pte_unmap_unlock(vmf->pte, vmf->ptl);
2434 }
2435 
2436 /*
2437  * Handle the case of a page which we actually need to copy to a new page.
2438  *
2439  * Called with mmap_sem locked and the old page referenced, but
2440  * without the ptl held.
2441  *
2442  * High level logic flow:
2443  *
2444  * - Allocate a page, copy the content of the old page to the new one.
2445  * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2446  * - Take the PTL. If the pte changed, bail out and release the allocated page
2447  * - If the pte is still the way we remember it, update the page table and all
2448  *   relevant references. This includes dropping the reference the page-table
2449  *   held to the old page, as well as updating the rmap.
2450  * - In any case, unlock the PTL and drop the reference we took to the old page.
2451  */
2452 static int wp_page_copy(struct vm_fault *vmf)
2453 {
2454         struct vm_area_struct *vma = vmf->vma;
2455         struct mm_struct *mm = vma->vm_mm;
2456         struct page *old_page = vmf->page;
2457         struct page *new_page = NULL;
2458         pte_t entry;
2459         int page_copied = 0;
2460         const unsigned long mmun_start = vmf->address & PAGE_MASK;
2461         const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2462         struct mem_cgroup *memcg;
2463 
2464         if (unlikely(anon_vma_prepare(vma)))
2465                 goto oom;
2466 
2467         if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2468                 new_page = alloc_zeroed_user_highpage_movable(vma,
2469                                                               vmf->address);
2470                 if (!new_page)
2471                         goto oom;
2472         } else {
2473                 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2474                                 vmf->address);
2475                 if (!new_page)
2476                         goto oom;
2477                 cow_user_page(new_page, old_page, vmf->address, vma);
2478         }
2479 
2480         if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2481                 goto oom_free_new;
2482 
2483         __SetPageUptodate(new_page);
2484 
2485         mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2486 
2487         /*
2488          * Re-check the pte - we dropped the lock
2489          */
2490         vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2491         if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2492                 if (old_page) {
2493                         if (!PageAnon(old_page)) {
2494                                 dec_mm_counter_fast(mm,
2495                                                 mm_counter_file(old_page));
2496                                 inc_mm_counter_fast(mm, MM_ANONPAGES);
2497                         }
2498                 } else {
2499                         inc_mm_counter_fast(mm, MM_ANONPAGES);
2500                 }
2501                 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2502                 entry = mk_pte(new_page, vma->vm_page_prot);
2503                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2504                 /*
2505                  * Clear the pte entry and flush it first, before updating the
2506                  * pte with the new entry. This will avoid a race condition
2507                  * seen in the presence of one thread doing SMC and another
2508                  * thread doing COW.
2509                  */
2510                 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2511                 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2512                 mem_cgroup_commit_charge(new_page, memcg, false, false);
2513                 lru_cache_add_active_or_unevictable(new_page, vma);
2514                 /*
2515                  * We call the notify macro here because, when using secondary
2516                  * mmu page tables (such as kvm shadow page tables), we want the
2517                  * new page to be mapped directly into the secondary page table.
2518                  */
2519                 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2520                 update_mmu_cache(vma, vmf->address, vmf->pte);
2521                 if (old_page) {
2522                         /*
2523                          * Only after switching the pte to the new page may
2524                          * we remove the mapcount here. Otherwise another
2525                          * process may come and find the rmap count decremented
2526                          * before the pte is switched to the new page, and
2527                          * "reuse" the old page writing into it while our pte
2528                          * here still points into it and can be read by other
2529                          * threads.
2530                          *
2531                          * The critical issue is to order this
2532                          * page_remove_rmap with the ptp_clear_flush above.
2533                          * Those stores are ordered by (if nothing else,)
2534                          * the barrier present in the atomic_add_negative
2535                          * in page_remove_rmap.
2536                          *
2537                          * Then the TLB flush in ptep_clear_flush ensures that
2538                          * no process can access the old page before the
2539                          * decremented mapcount is visible. And the old page
2540                          * cannot be reused until after the decremented
2541                          * mapcount is visible. So transitively, TLBs to
2542                          * old page will be flushed before it can be reused.
2543                          */
2544                         page_remove_rmap(old_page, false);
2545                 }
2546 
2547                 /* Free the old page.. */
2548                 new_page = old_page;
2549                 page_copied = 1;
2550         } else {
2551                 mem_cgroup_cancel_charge(new_page, memcg, false);
2552         }
2553 
2554         if (new_page)
2555                 put_page(new_page);
2556 
2557         pte_unmap_unlock(vmf->pte, vmf->ptl);
2558         /*
2559          * No need to double call mmu_notifier->invalidate_range() callback as
2560          * the above ptep_clear_flush_notify() did already call it.
2561          */
2562         mmu_notifier_invalidate_range_only_end(mm, mmun_start, mmun_end);
2563         if (old_page) {
2564                 /*
2565                  * Don't let another task, with possibly unlocked vma,
2566                  * keep the mlocked page.
2567                  */
2568                 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2569                         lock_page(old_page);    /* LRU manipulation */
2570                         if (PageMlocked(old_page))
2571                                 munlock_vma_page(old_page);
2572                         unlock_page(old_page);
2573                 }
2574                 put_page(old_page);
2575         }
2576         return page_copied ? VM_FAULT_WRITE : 0;
2577 oom_free_new:
2578         put_page(new_page);
2579 oom:
2580         if (old_page)
2581                 put_page(old_page);
2582         return VM_FAULT_OOM;
2583 }
2584 
2585 /**
2586  * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2587  *                        writeable once the page is prepared
2588  *
2589  * @vmf: structure describing the fault
2590  *
2591  * This function handles all that is needed to finish a write page fault in a
2592  * shared mapping due to PTE being read-only once the mapped page is prepared.
2593  * It handles locking of PTE and modifying it. The function returns
2594  * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE
2595  * lock.
2596  *
2597  * The function expects the page to be locked or other protection against
2598  * concurrent faults / writeback (such as DAX radix tree locks).
2599  */
2600 int finish_mkwrite_fault(struct vm_fault *vmf)
2601 {
2602         WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2603         vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2604                                        &vmf->ptl);
2605         /*
2606          * We might have raced with another page fault while we released the
2607          * pte_offset_map_lock.
2608          */
2609         if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2610                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2611                 return VM_FAULT_NOPAGE;
2612         }
2613         wp_page_reuse(vmf);
2614         return 0;
2615 }
2616 
2617 /*
2618  * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2619  * mapping
2620  */
2621 static int wp_pfn_shared(struct vm_fault *vmf)
2622 {
2623         struct vm_area_struct *vma = vmf->vma;
2624 
2625         if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2626                 int ret;
2627 
2628                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2629                 vmf->flags |= FAULT_FLAG_MKWRITE;
2630                 ret = vma->vm_ops->pfn_mkwrite(vmf);
2631                 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2632                         return ret;
2633                 return finish_mkwrite_fault(vmf);
2634         }
2635         wp_page_reuse(vmf);
2636         return VM_FAULT_WRITE;
2637 }
2638 
2639 static int wp_page_shared(struct vm_fault *vmf)
2640         __releases(vmf->ptl)
2641 {
2642         struct vm_area_struct *vma = vmf->vma;
2643 
2644         get_page(vmf->page);
2645 
2646         if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2647                 int tmp;
2648 
2649                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2650                 tmp = do_page_mkwrite(vmf);
2651                 if (unlikely(!tmp || (tmp &
2652                                       (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2653                         put_page(vmf->page);
2654                         return tmp;
2655                 }
2656                 tmp = finish_mkwrite_fault(vmf);
2657                 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2658                         unlock_page(vmf->page);
2659                         put_page(vmf->page);
2660                         return tmp;
2661                 }
2662         } else {
2663                 wp_page_reuse(vmf);
2664                 lock_page(vmf->page);
2665         }
2666         fault_dirty_shared_page(vma, vmf->page);
2667         put_page(vmf->page);
2668 
2669         return VM_FAULT_WRITE;
2670 }
2671 
2672 /*
2673  * This routine handles present pages, when users try to write
2674  * to a shared page. It is done by copying the page to a new address
2675  * and decrementing the shared-page counter for the old page.
2676  *
2677  * Note that this routine assumes that the protection checks have been
2678  * done by the caller (the low-level page fault routine in most cases).
2679  * Thus we can safely just mark it writable once we've done any necessary
2680  * COW.
2681  *
2682  * We also mark the page dirty at this point even though the page will
2683  * change only once the write actually happens. This avoids a few races,
2684  * and potentially makes it more efficient.
2685  *
2686  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2687  * but allow concurrent faults), with pte both mapped and locked.
2688  * We return with mmap_sem still held, but pte unmapped and unlocked.
2689  */
2690 static int do_wp_page(struct vm_fault *vmf)
2691         __releases(vmf->ptl)
2692 {
2693         struct vm_area_struct *vma = vmf->vma;
2694 
2695         vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2696         if (!vmf->page) {
2697                 /*
2698                  * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2699                  * VM_PFNMAP VMA.
2700                  *
2701                  * We should not cow pages in a shared writeable mapping.
2702                  * Just mark the pages writable and/or call ops->pfn_mkwrite.
2703                  */
2704                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2705                                      (VM_WRITE|VM_SHARED))
2706                         return wp_pfn_shared(vmf);
2707 
2708                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2709                 return wp_page_copy(vmf);
2710         }
2711 
2712         /*
2713          * Take out anonymous pages first, anonymous shared vmas are
2714          * not dirty accountable.
2715          */
2716         if (PageAnon(vmf->page) && !PageKsm(vmf->page)) {
2717                 int total_map_swapcount;
2718                 if (!trylock_page(vmf->page)) {
2719                         get_page(vmf->page);
2720                         pte_unmap_unlock(vmf->pte, vmf->ptl);
2721                         lock_page(vmf->page);
2722                         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2723                                         vmf->address, &vmf->ptl);
2724                         if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2725                                 unlock_page(vmf->page);
2726                                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2727                                 put_page(vmf->page);
2728                                 return 0;
2729                         }
2730                         put_page(vmf->page);
2731                 }
2732                 if (reuse_swap_page(vmf->page, &total_map_swapcount)) {
2733                         if (total_map_swapcount == 1) {
2734                                 /*
2735                                  * The page is all ours. Move it to
2736                                  * our anon_vma so the rmap code will
2737                                  * not search our parent or siblings.
2738                                  * Protected against the rmap code by
2739                                  * the page lock.
2740                                  */
2741                                 page_move_anon_rmap(vmf->page, vma);
2742                         }
2743                         unlock_page(vmf->page);
2744                         wp_page_reuse(vmf);
2745                         return VM_FAULT_WRITE;
2746                 }
2747                 unlock_page(vmf->page);
2748         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2749                                         (VM_WRITE|VM_SHARED))) {
2750                 return wp_page_shared(vmf);
2751         }
2752 
2753         /*
2754          * Ok, we need to copy. Oh, well..
2755          */
2756         get_page(vmf->page);
2757 
2758         pte_unmap_unlock(vmf->pte, vmf->ptl);
2759         return wp_page_copy(vmf);
2760 }
2761 
2762 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2763                 unsigned long start_addr, unsigned long end_addr,
2764                 struct zap_details *details)
2765 {
2766         zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2767 }
2768 
2769 static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
2770                                             struct zap_details *details)
2771 {
2772         struct vm_area_struct *vma;
2773         pgoff_t vba, vea, zba, zea;
2774 
2775         vma_interval_tree_foreach(vma, root,
2776                         details->first_index, details->last_index) {
2777 
2778                 vba = vma->vm_pgoff;
2779                 vea = vba + vma_pages(vma) - 1;
2780                 zba = details->first_index;
2781                 if (zba < vba)
2782                         zba = vba;
2783                 zea = details->last_index;
2784                 if (zea > vea)
2785                         zea = vea;
2786 
2787                 unmap_mapping_range_vma(vma,
2788                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2789                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2790                                 details);
2791         }
2792 }
2793 
2794 /**
2795  * unmap_mapping_range - unmap the portion of all mmaps in the specified
2796  * address_space corresponding to the specified page range in the underlying
2797  * file.
2798  *
2799  * @mapping: the address space containing mmaps to be unmapped.
2800  * @holebegin: byte in first page to unmap, relative to the start of
2801  * the underlying file.  This will be rounded down to a PAGE_SIZE
2802  * boundary.  Note that this is different from truncate_pagecache(), which
2803  * must keep the partial page.  In contrast, we must get rid of
2804  * partial pages.
2805  * @holelen: size of prospective hole in bytes.  This will be rounded
2806  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2807  * end of the file.
2808  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2809  * but 0 when invalidating pagecache, don't throw away private data.
2810  */
2811 void unmap_mapping_range(struct address_space *mapping,
2812                 loff_t const holebegin, loff_t const holelen, int even_cows)
2813 {
2814         struct zap_details details = { };
2815         pgoff_t hba = holebegin >> PAGE_SHIFT;
2816         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2817 
2818         /* Check for overflow. */
2819         if (sizeof(holelen) > sizeof(hlen)) {
2820                 long long holeend =
2821                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2822                 if (holeend & ~(long long)ULONG_MAX)
2823                         hlen = ULONG_MAX - hba + 1;
2824         }
2825 
2826         details.check_mapping = even_cows ? NULL : mapping;
2827         details.first_index = hba;
2828         details.last_index = hba + hlen - 1;
2829         if (details.last_index < details.first_index)
2830                 details.last_index = ULONG_MAX;
2831 
2832         i_mmap_lock_write(mapping);
2833         if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
2834                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2835         i_mmap_unlock_write(mapping);
2836 }
2837 EXPORT_SYMBOL(unmap_mapping_range);
2838 
2839 /*
2840  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2841  * but allow concurrent faults), and pte mapped but not yet locked.
2842  * We return with pte unmapped and unlocked.
2843  *
2844  * We return with the mmap_sem locked or unlocked in the same cases
2845  * as does filemap_fault().
2846  */
2847 int do_swap_page(struct vm_fault *vmf)
2848 {
2849         struct vm_area_struct *vma = vmf->vma;
2850         struct page *page = NULL, *swapcache = NULL;
2851         struct mem_cgroup *memcg;
2852         struct vma_swap_readahead swap_ra;
2853         swp_entry_t entry;
2854         pte_t pte;
2855         int locked;
2856         int exclusive = 0;
2857         int ret = 0;
2858         bool vma_readahead = swap_use_vma_readahead();
2859 
2860         if (vma_readahead) {
2861                 page = swap_readahead_detect(vmf, &swap_ra);
2862                 swapcache = page;
2863         }
2864 
2865         if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte)) {
2866                 if (page)
2867                         put_page(page);
2868                 goto out;
2869         }
2870 
2871         entry = pte_to_swp_entry(vmf->orig_pte);
2872         if (unlikely(non_swap_entry(entry))) {
2873                 if (is_migration_entry(entry)) {
2874                         migration_entry_wait(vma->vm_mm, vmf->pmd,
2875                                              vmf->address);
2876                 } else if (is_device_private_entry(entry)) {
2877                         /*
2878                          * For un-addressable device memory we call the pgmap
2879                          * fault handler callback. The callback must migrate
2880                          * the page back to some CPU accessible page.
2881                          */
2882                         ret = device_private_entry_fault(vma, vmf->address, entry,
2883                                                  vmf->flags, vmf->pmd);
2884                 } else if (is_hwpoison_entry(entry)) {
2885                         ret = VM_FAULT_HWPOISON;
2886                 } else {
2887                         print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
2888                         ret = VM_FAULT_SIGBUS;
2889                 }
2890                 goto out;
2891         }
2892 
2893 
2894         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2895         if (!page) {
2896                 page = lookup_swap_cache(entry, vma_readahead ? vma : NULL,
2897                                          vmf->address);
2898                 swapcache = page;
2899         }
2900 
2901         if (!page) {
2902                 struct swap_info_struct *si = swp_swap_info(entry);
2903 
2904                 if (si->flags & SWP_SYNCHRONOUS_IO &&
2905                                 __swap_count(si, entry) == 1) {
2906                         /* skip swapcache */
2907                         page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
2908                         if (page) {
2909                                 __SetPageLocked(page);
2910                                 __SetPageSwapBacked(page);
2911                                 set_page_private(page, entry.val);
2912                                 lru_cache_add_anon(page);
2913                                 swap_readpage(page, true);
2914                         }
2915                 } else {
2916                         if (vma_readahead)
2917                                 page = do_swap_page_readahead(entry,
2918                                         GFP_HIGHUSER_MOVABLE, vmf, &swap_ra);
2919                         else
2920                                 page = swapin_readahead(entry,
2921                                        GFP_HIGHUSER_MOVABLE, vma, vmf->address);
2922                         swapcache = page;
2923                 }
2924 
2925                 if (!page) {
2926                         /*
2927                          * Back out if somebody else faulted in this pte
2928                          * while we released the pte lock.
2929                          */
2930                         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2931                                         vmf->address, &vmf->ptl);
2932                         if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
2933                                 ret = VM_FAULT_OOM;
2934                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2935                         goto unlock;
2936                 }
2937 
2938                 /* Had to read the page from swap area: Major fault */
2939                 ret = VM_FAULT_MAJOR;
2940                 count_vm_event(PGMAJFAULT);
2941                 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
2942         } else if (PageHWPoison(page)) {
2943                 /*
2944                  * hwpoisoned dirty swapcache pages are kept for killing
2945                  * owner processes (which may be unknown at hwpoison time)
2946                  */
2947                 ret = VM_FAULT_HWPOISON;
2948                 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2949                 swapcache = page;
2950                 goto out_release;
2951         }
2952 
2953         locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
2954 
2955         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2956         if (!locked) {
2957                 ret |= VM_FAULT_RETRY;
2958                 goto out_release;
2959         }
2960 
2961         /*
2962          * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2963          * release the swapcache from under us.  The page pin, and pte_same
2964          * test below, are not enough to exclude that.  Even if it is still
2965          * swapcache, we need to check that the page's swap has not changed.
2966          */
2967         if (unlikely((!PageSwapCache(page) ||
2968                         page_private(page) != entry.val)) && swapcache)
2969                 goto out_page;
2970 
2971         page = ksm_might_need_to_copy(page, vma, vmf->address);
2972         if (unlikely(!page)) {
2973                 ret = VM_FAULT_OOM;
2974                 page = swapcache;
2975                 goto out_page;
2976         }
2977 
2978         if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
2979                                 &memcg, false)) {
2980                 ret = VM_FAULT_OOM;
2981                 goto out_page;
2982         }
2983 
2984         /*
2985          * Back out if somebody else already faulted in this pte.
2986          */
2987         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2988                         &vmf->ptl);
2989         if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
2990                 goto out_nomap;
2991 
2992         if (unlikely(!PageUptodate(page))) {
2993                 ret = VM_FAULT_SIGBUS;
2994                 goto out_nomap;
2995         }
2996 
2997         /*
2998          * The page isn't present yet, go ahead with the fault.
2999          *
3000          * Be careful about the sequence of operations here.
3001          * To get its accounting right, reuse_swap_page() must be called
3002          * while the page is counted on swap but not yet in mapcount i.e.
3003          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3004          * must be called after the swap_free(), or it will never succeed.
3005          */
3006 
3007         inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3008         dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
3009         pte = mk_pte(page, vma->vm_page_prot);
3010         if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
3011                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3012                 vmf->flags &= ~FAULT_FLAG_WRITE;
3013                 ret |= VM_FAULT_WRITE;
3014                 exclusive = RMAP_EXCLUSIVE;
3015         }
3016         flush_icache_page(vma, page);
3017         if (pte_swp_soft_dirty(vmf->orig_pte))
3018                 pte = pte_mksoft_dirty(pte);
3019         set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3020         vmf->orig_pte = pte;
3021 
3022         /* ksm created a completely new copy */
3023         if (unlikely(page != swapcache && swapcache)) {
3024                 page_add_new_anon_rmap(page, vma, vmf->address, false);
3025                 mem_cgroup_commit_charge(page, memcg, false, false);
3026                 lru_cache_add_active_or_unevictable(page, vma);
3027         } else {
3028                 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
3029                 mem_cgroup_commit_charge(page, memcg, true, false);
3030                 activate_page(page);
3031         }
3032 
3033         swap_free(entry);
3034         if (mem_cgroup_swap_full(page) ||
3035             (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3036                 try_to_free_swap(page);
3037         unlock_page(page);
3038         if (page != swapcache && swapcache) {
3039                 /*
3040                  * Hold the lock to avoid the swap entry to be reused
3041                  * until we take the PT lock for the pte_same() check
3042                  * (to avoid false positives from pte_same). For
3043                  * further safety release the lock after the swap_free
3044                  * so that the swap count won't change under a
3045                  * parallel locked swapcache.
3046                  */
3047                 unlock_page(swapcache);
3048                 put_page(swapcache);
3049         }
3050 
3051         if (vmf->flags & FAULT_FLAG_WRITE) {
3052                 ret |= do_wp_page(vmf);
3053                 if (ret & VM_FAULT_ERROR)
3054                         ret &= VM_FAULT_ERROR;
3055                 goto out;
3056         }
3057 
3058         /* No need to invalidate - it was non-present before */
3059         update_mmu_cache(vma, vmf->address, vmf->pte);
3060 unlock:
3061         pte_unmap_unlock(vmf->pte, vmf->ptl);
3062 out:
3063         return ret;
3064 out_nomap:
3065         mem_cgroup_cancel_charge(page, memcg, false);
3066         pte_unmap_unlock(vmf->pte, vmf->ptl);
3067 out_page:
3068         unlock_page(page);
3069 out_release:
3070         put_page(page);
3071         if (page != swapcache && swapcache) {
3072                 unlock_page(swapcache);
3073                 put_page(swapcache);
3074         }
3075         return ret;
3076 }
3077 
3078 /*
3079  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3080  * but allow concurrent faults), and pte mapped but not yet locked.
3081  * We return with mmap_sem still held, but pte unmapped and unlocked.
3082  */
3083 static int do_anonymous_page(struct vm_fault *vmf)
3084 {
3085         struct vm_area_struct *vma = vmf->vma;
3086         struct mem_cgroup *memcg;
3087         struct page *page;
3088         int ret = 0;
3089         pte_t entry;
3090 
3091         /* File mapping without ->vm_ops ? */
3092         if (vma->vm_flags & VM_SHARED)
3093                 return VM_FAULT_SIGBUS;
3094 
3095         /*
3096          * Use pte_alloc() instead of pte_alloc_map().  We can't run
3097          * pte_offset_map() on pmds where a huge pmd might be created
3098          * from a different thread.
3099          *
3100          * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
3101          * parallel threads are excluded by other means.
3102          *
3103          * Here we only have down_read(mmap_sem).
3104          */
3105         if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
3106                 return VM_FAULT_OOM;
3107 
3108         /* See the comment in pte_alloc_one_map() */
3109         if (unlikely(pmd_trans_unstable(vmf->pmd)))
3110                 return 0;
3111 
3112         /* Use the zero-page for reads */
3113         if (!(vmf->flags & FAULT_FLAG_WRITE) &&
3114                         !mm_forbids_zeropage(vma->vm_mm)) {
3115                 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
3116                                                 vma->vm_page_prot));
3117                 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3118                                 vmf->address, &vmf->ptl);
3119                 if (!pte_none(*vmf->pte))
3120                         goto unlock;
3121                 ret = check_stable_address_space(vma->vm_mm);
3122                 if (ret)
3123                         goto unlock;
3124                 /* Deliver the page fault to userland, check inside PT lock */
3125                 if (userfaultfd_missing(vma)) {
3126                         pte_unmap_unlock(vmf->pte, vmf->ptl);
3127                         return handle_userfault(vmf, VM_UFFD_MISSING);
3128                 }
3129                 goto setpte;
3130         }
3131 
3132         /* Allocate our own private page. */
3133         if (unlikely(anon_vma_prepare(vma)))
3134                 goto oom;
3135         page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3136         if (!page)
3137                 goto oom;
3138 
3139         if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
3140                 goto oom_free_page;
3141 
3142         /*
3143          * The memory barrier inside __SetPageUptodate makes sure that
3144          * preceeding stores to the page contents become visible before
3145          * the set_pte_at() write.
3146          */
3147         __SetPageUptodate(page);
3148 
3149         entry = mk_pte(page, vma->vm_page_prot);
3150         if (vma->vm_flags & VM_WRITE)
3151                 entry = pte_mkwrite(pte_mkdirty(entry));
3152 
3153         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3154                         &vmf->ptl);
3155         if (!pte_none(*vmf->pte))
3156                 goto release;
3157 
3158         ret = check_stable_address_space(vma->vm_mm);
3159         if (ret)
3160                 goto release;
3161 
3162         /* Deliver the page fault to userland, check inside PT lock */
3163         if (userfaultfd_missing(vma)) {
3164                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3165                 mem_cgroup_cancel_charge(page, memcg, false);
3166                 put_page(page);
3167                 return handle_userfault(vmf, VM_UFFD_MISSING);
3168         }
3169 
3170         inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3171         page_add_new_anon_rmap(page, vma, vmf->address, false);
3172         mem_cgroup_commit_charge(page, memcg, false, false);
3173         lru_cache_add_active_or_unevictable(page, vma);
3174 setpte:
3175         set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3176 
3177         /* No need to invalidate - it was non-present before */
3178         update_mmu_cache(vma, vmf->address, vmf->pte);
3179 unlock:
3180         pte_unmap_unlock(vmf->pte, vmf->ptl);
3181         return ret;
3182 release:
3183         mem_cgroup_cancel_charge(page, memcg, false);
3184         put_page(page);
3185         goto unlock;
3186 oom_free_page:
3187         put_page(page);
3188 oom:
3189         return VM_FAULT_OOM;
3190 }
3191 
3192 /*
3193  * The mmap_sem must have been held on entry, and may have been
3194  * released depending on flags and vma->vm_ops->fault() return value.
3195  * See filemap_fault() and __lock_page_retry().
3196  */
3197 static int __do_fault(struct vm_fault *vmf)
3198 {
3199         struct vm_area_struct *vma = vmf->vma;
3200         int ret;
3201 
3202         ret = vma->vm_ops->fault(vmf);
3203         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3204                             VM_FAULT_DONE_COW)))
3205                 return ret;
3206 
3207         if (unlikely(PageHWPoison(vmf->page))) {
3208                 if (ret & VM_FAULT_LOCKED)
3209                         unlock_page(vmf->page);
3210                 put_page(vmf->page);
3211                 vmf->page = NULL;
3212                 return VM_FAULT_HWPOISON;
3213         }
3214 
3215         if (unlikely(!(ret & VM_FAULT_LOCKED)))
3216                 lock_page(vmf->page);
3217         else
3218                 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3219 
3220         return ret;
3221 }
3222 
3223 /*
3224  * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
3225  * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
3226  * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
3227  * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3228  */
3229 static int pmd_devmap_trans_unstable(pmd_t *pmd)
3230 {
3231         return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3232 }
3233 
3234 static int pte_alloc_one_map(struct vm_fault *vmf)
3235 {
3236         struct vm_area_struct *vma = vmf->vma;
3237 
3238         if (!pmd_none(*vmf->pmd))
3239                 goto map_pte;
3240         if (vmf->prealloc_pte) {
3241                 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3242                 if (unlikely(!pmd_none(*vmf->pmd))) {
3243                         spin_unlock(vmf->ptl);
3244                         goto map_pte;
3245                 }
3246 
3247                 mm_inc_nr_ptes(vma->vm_mm);
3248                 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3249                 spin_unlock(vmf->ptl);
3250                 vmf->prealloc_pte = NULL;
3251         } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
3252                 return VM_FAULT_OOM;
3253         }
3254 map_pte:
3255         /*
3256          * If a huge pmd materialized under us just retry later.  Use
3257          * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3258          * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3259          * under us and then back to pmd_none, as a result of MADV_DONTNEED
3260          * running immediately after a huge pmd fault in a different thread of
3261          * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3262          * All we have to ensure is that it is a regular pmd that we can walk
3263          * with pte_offset_map() and we can do that through an atomic read in
3264          * C, which is what pmd_trans_unstable() provides.
3265          */
3266         if (pmd_devmap_trans_unstable(vmf->pmd))
3267                 return VM_FAULT_NOPAGE;
3268 
3269         /*
3270          * At this point we know that our vmf->pmd points to a page of ptes
3271          * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3272          * for the duration of the fault.  If a racing MADV_DONTNEED runs and
3273          * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3274          * be valid and we will re-check to make sure the vmf->pte isn't
3275          * pte_none() under vmf->ptl protection when we return to
3276          * alloc_set_pte().
3277          */
3278         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3279                         &vmf->ptl);
3280         return 0;
3281 }
3282 
3283 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3284 
3285 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
3286 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
3287                 unsigned long haddr)
3288 {
3289         if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
3290                         (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
3291                 return false;
3292         if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
3293                 return false;
3294         return true;
3295 }
3296 
3297 static void deposit_prealloc_pte(struct vm_fault *vmf)
3298 {
3299         struct vm_area_struct *vma = vmf->vma;
3300 
3301         pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3302         /*
3303          * We are going to consume the prealloc table,
3304          * count that as nr_ptes.
3305          */
3306         mm_inc_nr_ptes(vma->vm_mm);
3307         vmf->prealloc_pte = NULL;
3308 }
3309 
3310 static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3311 {
3312         struct vm_area_struct *vma = vmf->vma;
3313         bool write = vmf->flags & FAULT_FLAG_WRITE;
3314         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3315         pmd_t entry;
3316         int i, ret;
3317 
3318         if (!transhuge_vma_suitable(vma, haddr))
3319                 return VM_FAULT_FALLBACK;
3320 
3321         ret = VM_FAULT_FALLBACK;
3322         page = compound_head(page);
3323 
3324         /*
3325          * Archs like ppc64 need additonal space to store information
3326          * related to pte entry. Use the preallocated table for that.
3327          */
3328         if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3329                 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
3330                 if (!vmf->prealloc_pte)
3331                         return VM_FAULT_OOM;
3332                 smp_wmb(); /* See comment in __pte_alloc() */
3333         }
3334 
3335         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3336         if (unlikely(!pmd_none(*vmf->pmd)))
3337                 goto out;
3338 
3339         for (i = 0; i < HPAGE_PMD_NR; i++)
3340                 flush_icache_page(vma, page + i);
3341 
3342         entry = mk_huge_pmd(page, vma->vm_page_prot);
3343         if (write)
3344                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3345 
3346         add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
3347         page_add_file_rmap(page, true);
3348         /*
3349          * deposit and withdraw with pmd lock held
3350          */
3351         if (arch_needs_pgtable_deposit())
3352                 deposit_prealloc_pte(vmf);
3353 
3354         set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3355 
3356         update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3357 
3358         /* fault is handled */
3359         ret = 0;
3360         count_vm_event(THP_FILE_MAPPED);
3361 out:
3362         spin_unlock(vmf->ptl);
3363         return ret;
3364 }
3365 #else
3366 static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3367 {
3368         BUILD_BUG();
3369         return 0;
3370 }
3371 #endif
3372 
3373 /**
3374  * alloc_set_pte - setup new PTE entry for given page and add reverse page
3375  * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3376  *
3377  * @vmf: fault environment
3378  * @memcg: memcg to charge page (only for private mappings)
3379  * @page: page to map
3380  *
3381  * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3382  * return.
3383  *
3384  * Target users are page handler itself and implementations of
3385  * vm_ops->map_pages.
3386  */
3387 int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3388                 struct page *page)
3389 {
3390         struct vm_area_struct *vma = vmf->vma;
3391         bool write = vmf->flags & FAULT_FLAG_WRITE;
3392         pte_t entry;
3393         int ret;
3394 
3395         if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3396                         IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3397                 /* THP on COW? */
3398                 VM_BUG_ON_PAGE(memcg, page);
3399 
3400                 ret = do_set_pmd(vmf, page);
3401                 if (ret != VM_FAULT_FALLBACK)
3402                         return ret;
3403         }
3404 
3405         if (!vmf->pte) {
3406                 ret = pte_alloc_one_map(vmf);
3407                 if (ret)
3408                         return ret;
3409         }
3410 
3411         /* Re-check under ptl */
3412         if (unlikely(!pte_none(*vmf->pte)))
3413                 return VM_FAULT_NOPAGE;
3414 
3415         flush_icache_page(vma, page);
3416         entry = mk_pte(page, vma->vm_page_prot);
3417         if (write)
3418                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3419         /* copy-on-write page */
3420         if (write && !(vma->vm_flags & VM_SHARED)) {
3421                 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3422                 page_add_new_anon_rmap(page, vma, vmf->address, false);
3423                 mem_cgroup_commit_charge(page, memcg, false, false);
3424                 lru_cache_add_active_or_unevictable(page, vma);
3425         } else {
3426                 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3427                 page_add_file_rmap(page, false);
3428         }
3429         set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3430 
3431         /* no need to invalidate: a not-present page won't be cached */
3432         update_mmu_cache(vma, vmf->address, vmf->pte);
3433 
3434         return 0;
3435 }
3436 
3437 
3438 /**
3439  * finish_fault - finish page fault once we have prepared the page to fault
3440  *
3441  * @vmf: structure describing the fault
3442  *
3443  * This function handles all that is needed to finish a page fault once the
3444  * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3445  * given page, adds reverse page mapping, handles memcg charges and LRU
3446  * addition. The function returns 0 on success, VM_FAULT_ code in case of
3447  * error.
3448  *
3449  * The function expects the page to be locked and on success it consumes a
3450  * reference of a page being mapped (for the PTE which maps it).
3451  */
3452 int finish_fault(struct vm_fault *vmf)
3453 {
3454         struct page *page;
3455         int ret = 0;
3456 
3457         /* Did we COW the page? */
3458         if ((vmf->flags & FAULT_FLAG_WRITE) &&
3459             !(vmf->vma->vm_flags & VM_SHARED))
3460                 page = vmf->cow_page;
3461         else
3462                 page = vmf->page;
3463 
3464         /*
3465          * check even for read faults because we might have lost our CoWed
3466          * page
3467          */
3468         if (!(vmf->vma->vm_flags & VM_SHARED))
3469                 ret = check_stable_address_space(vmf->vma->vm_mm);
3470         if (!ret)
3471                 ret = alloc_set_pte(vmf, vmf->memcg, page);
3472         if (vmf->pte)
3473                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3474         return ret;
3475 }
3476 
3477 static unsigned long fault_around_bytes __read_mostly =
3478         rounddown_pow_of_two(65536);
3479 
3480 #ifdef CONFIG_DEBUG_FS
3481 static int fault_around_bytes_get(void *data, u64 *val)
3482 {
3483         *val = fault_around_bytes;
3484         return 0;
3485 }
3486 
3487 /*
3488  * fault_around_pages() and fault_around_mask() expects fault_around_bytes
3489  * rounded down to nearest page order. It's what do_fault_around() expects to
3490  * see.
3491  */
3492 static int fault_around_bytes_set(void *data, u64 val)
3493 {
3494         if (val / PAGE_SIZE > PTRS_PER_PTE)
3495                 return -EINVAL;
3496         if (val > PAGE_SIZE)
3497                 fault_around_bytes = rounddown_pow_of_two(val);
3498         else
3499                 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3500         return 0;
3501 }
3502 DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3503                 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3504 
3505 static int __init fault_around_debugfs(void)
3506 {
3507         void *ret;
3508 
3509         ret = debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3510                         &fault_around_bytes_fops);
3511         if (!ret)
3512                 pr_warn("Failed to create fault_around_bytes in debugfs");
3513         return 0;
3514 }
3515 late_initcall(fault_around_debugfs);
3516 #endif
3517 
3518 /*
3519  * do_fault_around() tries to map few pages around the fault address. The hope
3520  * is that the pages will be needed soon and this will lower the number of
3521  * faults to handle.
3522  *
3523  * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3524  * not ready to be mapped: not up-to-date, locked, etc.
3525  *
3526  * This function is called with the page table lock taken. In the split ptlock
3527  * case the page table lock only protects only those entries which belong to
3528  * the page table corresponding to the fault address.
3529  *
3530  * This function doesn't cross the VMA boundaries, in order to call map_pages()
3531  * only once.
3532  *
3533  * fault_around_pages() defines how many pages we'll try to map.
3534  * do_fault_around() expects it to return a power of two less than or equal to
3535  * PTRS_PER_PTE.
3536  *
3537  * The virtual address of the area that we map is naturally aligned to the
3538  * fault_around_pages() value (and therefore to page order).  This way it's
3539  * easier to guarantee that we don't cross page table boundaries.
3540  */
3541 static int do_fault_around(struct vm_fault *vmf)
3542 {
3543         unsigned long address = vmf->address, nr_pages, mask;
3544         pgoff_t start_pgoff = vmf->pgoff;
3545         pgoff_t end_pgoff;
3546         int off, ret = 0;
3547 
3548         nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3549         mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3550 
3551         vmf->address = max(address & mask, vmf->vma->vm_start);
3552         off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3553         start_pgoff -= off;
3554 
3555         /*
3556          *  end_pgoff is either end of page table or end of vma
3557          *  or fault_around_pages() from start_pgoff, depending what is nearest.
3558          */
3559         end_pgoff = start_pgoff -
3560                 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3561                 PTRS_PER_PTE - 1;
3562         end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3563                         start_pgoff + nr_pages - 1);
3564 
3565         if (pmd_none(*vmf->pmd)) {
3566                 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
3567                                                   vmf->address);
3568                 if (!vmf->prealloc_pte)
3569                         goto out;
3570                 smp_wmb(); /* See comment in __pte_alloc() */
3571         }
3572 
3573         vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3574 
3575         /* Huge page is mapped? Page fault is solved */
3576         if (pmd_trans_huge(*vmf->pmd)) {
3577                 ret = VM_FAULT_NOPAGE;
3578                 goto out;
3579         }
3580 
3581         /* ->map_pages() haven't done anything useful. Cold page cache? */
3582         if (!vmf->pte)
3583                 goto out;
3584 
3585         /* check if the page fault is solved */
3586         vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3587         if (!pte_none(*vmf->pte))
3588                 ret = VM_FAULT_NOPAGE;
3589         pte_unmap_unlock(vmf->pte, vmf->ptl);
3590 out:
3591         vmf->address = address;
3592         vmf->pte = NULL;
3593         return ret;
3594 }
3595 
3596 static int do_read_fault(struct vm_fault *vmf)
3597 {
3598         struct vm_area_struct *vma = vmf->vma;
3599         int ret = 0;
3600 
3601         /*
3602          * Let's call ->map_pages() first and use ->fault() as fallback
3603          * if page by the offset is not ready to be mapped (cold cache or
3604          * something).
3605          */
3606         if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3607                 ret = do_fault_around(vmf);
3608                 if (ret)
3609                         return ret;
3610         }
3611 
3612         ret = __do_fault(vmf);
3613         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3614                 return ret;
3615 
3616         ret |= finish_fault(vmf);
3617         unlock_page(vmf->page);
3618         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3619                 put_page(vmf->page);
3620         return ret;
3621 }
3622 
3623 static int do_cow_fault(struct vm_fault *vmf)
3624 {
3625         struct vm_area_struct *vma = vmf->vma;
3626         int ret;
3627 
3628         if (unlikely(anon_vma_prepare(vma)))
3629                 return VM_FAULT_OOM;
3630 
3631         vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3632         if (!vmf->cow_page)
3633                 return VM_FAULT_OOM;
3634 
3635         if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3636                                 &vmf->memcg, false)) {
3637                 put_page(vmf->cow_page);
3638                 return VM_FAULT_OOM;
3639         }
3640 
3641         ret = __do_fault(vmf);
3642         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3643                 goto uncharge_out;
3644         if (ret & VM_FAULT_DONE_COW)
3645                 return ret;
3646 
3647         copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3648         __SetPageUptodate(vmf->cow_page);
3649 
3650         ret |= finish_fault(vmf);
3651         unlock_page(vmf->page);
3652         put_page(vmf->page);
3653         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3654                 goto uncharge_out;
3655         return ret;
3656 uncharge_out:
3657         mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3658         put_page(vmf->cow_page);
3659         return ret;
3660 }
3661 
3662 static int do_shared_fault(struct vm_fault *vmf)
3663 {
3664         struct vm_area_struct *vma = vmf->vma;
3665         int ret, tmp;
3666 
3667         ret = __do_fault(vmf);
3668         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3669                 return ret;
3670 
3671         /*
3672          * Check if the backing address space wants to know that the page is
3673          * about to become writable
3674          */
3675         if (vma->vm_ops->page_mkwrite) {
3676                 unlock_page(vmf->page);
3677                 tmp = do_page_mkwrite(vmf);
3678                 if (unlikely(!tmp ||
3679                                 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3680                         put_page(vmf->page);
3681                         return tmp;
3682                 }
3683         }
3684 
3685         ret |= finish_fault(vmf);
3686         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3687                                         VM_FAULT_RETRY))) {
3688                 unlock_page(vmf->page);
3689                 put_page(vmf->page);
3690                 return ret;
3691         }
3692 
3693         fault_dirty_shared_page(vma, vmf->page);
3694         return ret;
3695 }
3696 
3697 /*
3698  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3699  * but allow concurrent faults).
3700  * The mmap_sem may have been released depending on flags and our
3701  * return value.  See filemap_fault() and __lock_page_or_retry().
3702  */
3703 static int do_fault(struct vm_fault *vmf)
3704 {
3705         struct vm_area_struct *vma = vmf->vma;
3706         int ret;
3707 
3708         /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3709         if (!vma->vm_ops->fault)
3710                 ret = VM_FAULT_SIGBUS;
3711         else if (!(vmf->flags & FAULT_FLAG_WRITE))
3712                 ret = do_read_fault(vmf);
3713         else if (!(vma->vm_flags & VM_SHARED))
3714                 ret = do_cow_fault(vmf);
3715         else
3716                 ret = do_shared_fault(vmf);
3717 
3718         /* preallocated pagetable is unused: free it */
3719         if (vmf->prealloc_pte) {
3720                 pte_free(vma->vm_mm, vmf->prealloc_pte);
3721                 vmf->prealloc_pte = NULL;
3722         }
3723         return ret;
3724 }
3725 
3726 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3727                                 unsigned long addr, int page_nid,
3728                                 int *flags)
3729 {
3730         get_page(page);
3731 
3732         count_vm_numa_event(NUMA_HINT_FAULTS);
3733         if (page_nid == numa_node_id()) {
3734                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3735                 *flags |= TNF_FAULT_LOCAL;
3736         }
3737 
3738         return mpol_misplaced(page, vma, addr);
3739 }
3740 
3741 static int do_numa_page(struct vm_fault *vmf)
3742 {
3743         struct vm_area_struct *vma = vmf->vma;
3744         struct page *page = NULL;
3745         int page_nid = -1;
3746         int last_cpupid;
3747         int target_nid;
3748         bool migrated = false;
3749         pte_t pte;
3750         bool was_writable = pte_savedwrite(vmf->orig_pte);
3751         int flags = 0;
3752 
3753         /*
3754          * The "pte" at this point cannot be used safely without
3755          * validation through pte_unmap_same(). It's of NUMA type but
3756          * the pfn may be screwed if the read is non atomic.
3757          */
3758         vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
3759         spin_lock(vmf->ptl);
3760         if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3761                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3762                 goto out;
3763         }
3764 
3765         /*
3766          * Make it present again, Depending on how arch implementes non
3767          * accessible ptes, some can allow access by kernel mode.
3768          */
3769         pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
3770         pte = pte_modify(pte, vma->vm_page_prot);
3771         pte = pte_mkyoung(pte);
3772         if (was_writable)
3773                 pte = pte_mkwrite(pte);
3774         ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
3775         update_mmu_cache(vma, vmf->address, vmf->pte);
3776 
3777         page = vm_normal_page(vma, vmf->address, pte);
3778         if (!page) {
3779                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3780                 return 0;
3781         }
3782 
3783         /* TODO: handle PTE-mapped THP */
3784         if (PageCompound(page)) {
3785                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3786                 return 0;
3787         }
3788 
3789         /*
3790          * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3791          * much anyway since they can be in shared cache state. This misses
3792          * the case where a mapping is writable but the process never writes
3793          * to it but pte_write gets cleared during protection updates and
3794          * pte_dirty has unpredictable behaviour between PTE scan updates,
3795          * background writeback, dirty balancing and application behaviour.
3796          */
3797         if (!pte_write(pte))
3798                 flags |= TNF_NO_GROUP;
3799 
3800         /*
3801          * Flag if the page is shared between multiple address spaces. This
3802          * is later used when determining whether to group tasks together
3803          */
3804         if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3805                 flags |= TNF_SHARED;
3806 
3807         last_cpupid = page_cpupid_last(page);
3808         page_nid = page_to_nid(page);
3809         target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
3810                         &flags);
3811         pte_unmap_unlock(vmf->pte, vmf->ptl);
3812         if (target_nid == -1) {
3813                 put_page(page);
3814                 goto out;
3815         }
3816 
3817         /* Migrate to the requested node */
3818         migrated = migrate_misplaced_page(page, vma, target_nid);
3819         if (migrated) {
3820                 page_nid = target_nid;
3821                 flags |= TNF_MIGRATED;
3822         } else
3823                 flags |= TNF_MIGRATE_FAIL;
3824 
3825 out:
3826         if (page_nid != -1)
3827                 task_numa_fault(last_cpupid, page_nid, 1, flags);
3828         return 0;
3829 }
3830 
3831 static inline int create_huge_pmd(struct vm_fault *vmf)
3832 {
3833         if (vma_is_anonymous(vmf->vma))
3834                 return do_huge_pmd_anonymous_page(vmf);
3835         if (vmf->vma->vm_ops->huge_fault)
3836                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3837         return VM_FAULT_FALLBACK;
3838 }
3839 
3840 /* `inline' is required to avoid gcc 4.1.2 build error */
3841 static inline int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
3842 {
3843         if (vma_is_anonymous(vmf->vma))
3844                 return do_huge_pmd_wp_page(vmf, orig_pmd);
3845         if (vmf->vma->vm_ops->huge_fault)
3846                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3847 
3848         /* COW handled on pte level: split pmd */
3849         VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
3850         __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
3851 
3852         return VM_FAULT_FALLBACK;
3853 }
3854 
3855 static inline bool vma_is_accessible(struct vm_area_struct *vma)
3856 {
3857         return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3858 }
3859 
3860 static int create_huge_pud(struct vm_fault *vmf)
3861 {
3862 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3863         /* No support for anonymous transparent PUD pages yet */
3864         if (vma_is_anonymous(vmf->vma))
3865                 return VM_FAULT_FALLBACK;
3866         if (vmf->vma->vm_ops->huge_fault)
3867                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3868 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3869         return VM_FAULT_FALLBACK;
3870 }
3871 
3872 static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
3873 {
3874 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3875         /* No support for anonymous transparent PUD pages yet */
3876         if (vma_is_anonymous(vmf->vma))
3877                 return VM_FAULT_FALLBACK;
3878         if (vmf->vma->vm_ops->huge_fault)
3879                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3880 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3881         return VM_FAULT_FALLBACK;
3882 }
3883 
3884 /*
3885  * These routines also need to handle stuff like marking pages dirty
3886  * and/or accessed for architectures that don't do it in hardware (most
3887  * RISC architectures).  The early dirtying is also good on the i386.
3888  *
3889  * There is also a hook called "update_mmu_cache()" that architectures
3890  * with external mmu caches can use to update those (ie the Sparc or
3891  * PowerPC hashed page tables that act as extended TLBs).
3892  *
3893  * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3894  * concurrent faults).
3895  *
3896  * The mmap_sem may have been released depending on flags and our return value.
3897  * See filemap_fault() and __lock_page_or_retry().
3898  */
3899 static int handle_pte_fault(struct vm_fault *vmf)
3900 {
3901         pte_t entry;
3902 
3903         if (unlikely(pmd_none(*vmf->pmd))) {
3904                 /*
3905                  * Leave __pte_alloc() until later: because vm_ops->fault may
3906                  * want to allocate huge page, and if we expose page table
3907                  * for an instant, it will be difficult to retract from
3908                  * concurrent faults and from rmap lookups.
3909                  */
3910                 vmf->pte = NULL;
3911         } else {
3912                 /* See comment in pte_alloc_one_map() */
3913                 if (pmd_devmap_trans_unstable(vmf->pmd))
3914                         return 0;
3915                 /*
3916                  * A regular pmd is established and it can't morph into a huge
3917                  * pmd from under us anymore at this point because we hold the
3918                  * mmap_sem read mode and khugepaged takes it in write mode.
3919                  * So now it's safe to run pte_offset_map().
3920                  */
3921                 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
3922                 vmf->orig_pte = *vmf->pte;
3923 
3924                 /*
3925                  * some architectures can have larger ptes than wordsize,
3926                  * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3927                  * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
3928                  * accesses.  The code below just needs a consistent view
3929                  * for the ifs and we later double check anyway with the
3930                  * ptl lock held. So here a barrier will do.
3931                  */
3932                 barrier();
3933                 if (pte_none(vmf->orig_pte)) {
3934                         pte_unmap(vmf->pte);
3935                         vmf->pte = NULL;
3936                 }
3937         }
3938 
3939         if (!vmf->pte) {
3940                 if (vma_is_anonymous(vmf->vma))
3941                         return do_anonymous_page(vmf);
3942                 else
3943                         return do_fault(vmf);
3944         }
3945 
3946         if (!pte_present(vmf->orig_pte))
3947                 return do_swap_page(vmf);
3948 
3949         if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
3950                 return do_numa_page(vmf);
3951 
3952         vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
3953         spin_lock(vmf->ptl);
3954         entry = vmf->orig_pte;
3955         if (unlikely(!pte_same(*vmf->pte, entry)))
3956                 goto unlock;
3957         if (vmf->flags & FAULT_FLAG_WRITE) {
3958                 if (!pte_write(entry))
3959                         return do_wp_page(vmf);
3960                 entry = pte_mkdirty(entry);
3961         }
3962         entry = pte_mkyoung(entry);
3963         if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
3964                                 vmf->flags & FAULT_FLAG_WRITE)) {
3965                 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3966         } else {
3967                 /*
3968                  * This is needed only for protection faults but the arch code
3969                  * is not yet telling us if this is a protection fault or not.
3970                  * This still avoids useless tlb flushes for .text page faults
3971                  * with threads.
3972                  */
3973                 if (vmf->flags & FAULT_FLAG_WRITE)
3974                         flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3975         }
3976 unlock:
3977         pte_unmap_unlock(vmf->pte, vmf->ptl);
3978         return 0;
3979 }
3980 
3981 /*
3982  * By the time we get here, we already hold the mm semaphore
3983  *
3984  * The mmap_sem may have been released depending on flags and our
3985  * return value.  See filemap_fault() and __lock_page_or_retry().
3986  */
3987 static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3988                 unsigned int flags)
3989 {
3990         struct vm_fault vmf = {
3991                 .vma = vma,
3992                 .address = address & PAGE_MASK,
3993                 .flags = flags,
3994                 .pgoff = linear_page_index(vma, address),
3995                 .gfp_mask = __get_fault_gfp_mask(vma),
3996         };
3997         unsigned int dirty = flags & FAULT_FLAG_WRITE;
3998         struct mm_struct *mm = vma->vm_mm;
3999         pgd_t *pgd;
4000         p4d_t *p4d;
4001         int ret;
4002 
4003         pgd = pgd_offset(mm, address);
4004         p4d = p4d_alloc(mm, pgd, address);
4005         if (!p4d)
4006                 return VM_FAULT_OOM;
4007 
4008         vmf.pud = pud_alloc(mm, p4d, address);
4009         if (!vmf.pud)
4010                 return VM_FAULT_OOM;
4011         if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) {
4012                 ret = create_huge_pud(&vmf);
4013                 if (!(ret & VM_FAULT_FALLBACK))
4014                         return ret;
4015         } else {
4016                 pud_t orig_pud = *vmf.pud;
4017 
4018                 barrier();
4019                 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
4020 
4021                         /* NUMA case for anonymous PUDs would go here */
4022 
4023                         if (dirty && !pud_write(orig_pud)) {
4024                                 ret = wp_huge_pud(&vmf, orig_pud);
4025                                 if (!(ret & VM_FAULT_FALLBACK))
4026                                         return ret;
4027                         } else {
4028                                 huge_pud_set_accessed(&vmf, orig_pud);
4029                                 return 0;
4030                         }
4031                 }
4032         }
4033 
4034         vmf.pmd = pmd_alloc(mm, vmf.pud, address);
4035         if (!vmf.pmd)
4036                 return VM_FAULT_OOM;
4037         if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
4038                 ret = create_huge_pmd(&vmf);
4039                 if (!(ret & VM_FAULT_FALLBACK))
4040                         return ret;
4041         } else {
4042                 pmd_t orig_pmd = *vmf.pmd;
4043 
4044                 barrier();
4045                 if (unlikely(is_swap_pmd(orig_pmd))) {
4046                         VM_BUG_ON(thp_migration_supported() &&
4047                                           !is_pmd_migration_entry(orig_pmd));
4048                         if (is_pmd_migration_entry(orig_pmd))
4049                                 pmd_migration_entry_wait(mm, vmf.pmd);
4050                         return 0;
4051                 }
4052                 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
4053                         if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
4054                                 return do_huge_pmd_numa_page(&vmf, orig_pmd);
4055 
4056                         if (dirty && !pmd_write(orig_pmd)) {
4057                                 ret = wp_huge_pmd(&vmf, orig_pmd);
4058                                 if (!(ret & VM_FAULT_FALLBACK))
4059                                         return ret;
4060                         } else {
4061                                 huge_pmd_set_accessed(&vmf, orig_pmd);
4062                                 return 0;
4063                         }
4064                 }
4065         }
4066 
4067         return handle_pte_fault(&vmf);
4068 }
4069 
4070 /*
4071  * By the time we get here, we already hold the mm semaphore
4072  *
4073  * The mmap_sem may have been released depending on flags and our
4074  * return value.  See filemap_fault() and __lock_page_or_retry().
4075  */
4076 int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4077                 unsigned int flags)
4078 {
4079         int ret;
4080 
4081         __set_current_state(TASK_RUNNING);
4082 
4083         count_vm_event(PGFAULT);
4084         count_memcg_event_mm(vma->vm_mm, PGFAULT);
4085 
4086         /* do counter updates before entering really critical section. */
4087         check_sync_rss_stat(current);
4088 
4089         if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
4090                                             flags & FAULT_FLAG_INSTRUCTION,
4091                                             flags & FAULT_FLAG_REMOTE))
4092                 return VM_FAULT_SIGSEGV;
4093 
4094         /*
4095          * Enable the memcg OOM handling for faults triggered in user
4096          * space.  Kernel faults are handled more gracefully.
4097          */
4098         if (flags & FAULT_FLAG_USER)
4099                 mem_cgroup_oom_enable();
4100 
4101         if (unlikely(is_vm_hugetlb_page(vma)))
4102                 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4103         else
4104                 ret = __handle_mm_fault(vma, address, flags);
4105 
4106         if (flags & FAULT_FLAG_USER) {
4107                 mem_cgroup_oom_disable();
4108                 /*
4109                  * The task may have entered a memcg OOM situation but
4110                  * if the allocation error was handled gracefully (no
4111                  * VM_FAULT_OOM), there is no need to kill anything.
4112                  * Just clean up the OOM state peacefully.
4113                  */
4114                 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4115                         mem_cgroup_oom_synchronize(false);
4116         }
4117 
4118         return ret;
4119 }
4120 EXPORT_SYMBOL_GPL(handle_mm_fault);
4121 
4122 #ifndef __PAGETABLE_P4D_FOLDED
4123 /*
4124  * Allocate p4d page table.
4125  * We've already handled the fast-path in-line.
4126  */
4127 int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4128 {
4129         p4d_t *new = p4d_alloc_one(mm, address);
4130         if (!new)
4131                 return -ENOMEM;
4132 
4133         smp_wmb(); /* See comment in __pte_alloc */
4134 
4135         spin_lock(&mm->page_table_lock);
4136         if (pgd_present(*pgd))          /* Another has populated it */
4137                 p4d_free(mm, new);
4138         else
4139                 pgd_populate(mm, pgd, new);
4140         spin_unlock(&mm->page_table_lock);
4141         return 0;
4142 }
4143 #endif /* __PAGETABLE_P4D_FOLDED */
4144 
4145 #ifndef __PAGETABLE_PUD_FOLDED
4146 /*
4147  * Allocate page upper directory.
4148  * We've already handled the fast-path in-line.
4149  */
4150 int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4151 {
4152         pud_t *new = pud_alloc_one(mm, address);
4153         if (!new)
4154                 return -ENOMEM;
4155 
4156         smp_wmb(); /* See comment in __pte_alloc */
4157 
4158         spin_lock(&mm->page_table_lock);
4159 #ifndef __ARCH_HAS_5LEVEL_HACK
4160         if (!p4d_present(*p4d)) {
4161                 mm_inc_nr_puds(mm);
4162                 p4d_populate(mm, p4d, new);
4163         } else  /* Another has populated it */
4164                 pud_free(mm, new);
4165 #else
4166         if (!pgd_present(*p4d)) {
4167                 mm_inc_nr_puds(mm);
4168                 pgd_populate(mm, p4d, new);
4169         } else  /* Another has populated it */
4170                 pud_free(mm, new);
4171 #endif /* __ARCH_HAS_5LEVEL_HACK */
4172         spin_unlock(&mm->page_table_lock);
4173         return 0;
4174 }
4175 #endif /* __PAGETABLE_PUD_FOLDED */
4176 
4177 #ifndef __PAGETABLE_PMD_FOLDED
4178 /*
4179  * Allocate page middle directory.
4180  * We've already handled the fast-path in-line.
4181  */
4182 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4183 {
4184         spinlock_t *ptl;
4185         pmd_t *new = pmd_alloc_one(mm, address);
4186         if (!new)
4187                 return -ENOMEM;
4188 
4189         smp_wmb(); /* See comment in __pte_alloc */
4190 
4191         ptl = pud_lock(mm, pud);
4192 #ifndef __ARCH_HAS_4LEVEL_HACK
4193         if (!pud_present(*pud)) {
4194                 mm_inc_nr_pmds(mm);
4195                 pud_populate(mm, pud, new);
4196         } else  /* Another has populated it */
4197                 pmd_free(mm, new);
4198 #else
4199         if (!pgd_present(*pud)) {
4200                 mm_inc_nr_pmds(mm);
4201                 pgd_populate(mm, pud, new);
4202         } else /* Another has populated it */
4203                 pmd_free(mm, new);
4204 #endif /* __ARCH_HAS_4LEVEL_HACK */
4205         spin_unlock(ptl);
4206         return 0;
4207 }
4208 #endif /* __PAGETABLE_PMD_FOLDED */
4209 
4210 static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4211                             unsigned long *start, unsigned long *end,
4212                             pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4213 {
4214         pgd_t *pgd;
4215         p4d_t *p4d;
4216         pud_t *pud;
4217         pmd_t *pmd;
4218         pte_t *ptep;
4219 
4220         pgd = pgd_offset(mm, address);
4221         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4222                 goto out;
4223 
4224         p4d = p4d_offset(pgd, address);
4225         if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4226                 goto out;
4227 
4228         pud = pud_offset(p4d, address);
4229         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4230                 goto out;
4231 
4232         pmd = pmd_offset(pud, address);
4233         VM_BUG_ON(pmd_trans_huge(*pmd));
4234 
4235         if (pmd_huge(*pmd)) {
4236                 if (!pmdpp)
4237                         goto out;
4238 
4239                 if (start && end) {
4240                         *start = address & PMD_MASK;
4241                         *end = *start + PMD_SIZE;
4242                         mmu_notifier_invalidate_range_start(mm, *start, *end);
4243                 }
4244                 *ptlp = pmd_lock(mm, pmd);
4245                 if (pmd_huge(*pmd)) {
4246                         *pmdpp = pmd;
4247                         return 0;
4248                 }
4249                 spin_unlock(*ptlp);
4250                 if (start && end)
4251                         mmu_notifier_invalidate_range_end(mm, *start, *end);
4252         }
4253 
4254         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4255                 goto out;
4256 
4257         if (start && end) {
4258                 *start = address & PAGE_MASK;
4259                 *end = *start + PAGE_SIZE;
4260                 mmu_notifier_invalidate_range_start(mm, *start, *end);
4261         }
4262         ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4263         if (!pte_present(*ptep))
4264                 goto unlock;
4265         *ptepp = ptep;
4266         return 0;
4267 unlock:
4268         pte_unmap_unlock(ptep, *ptlp);
4269         if (start && end)
4270                 mmu_notifier_invalidate_range_end(mm, *start, *end);
4271 out:
4272         return -EINVAL;
4273 }
4274 
4275 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4276                              pte_t **ptepp, spinlock_t **ptlp)
4277 {
4278         int res;
4279 
4280         /* (void) is needed to make gcc happy */
4281         (void) __cond_lock(*ptlp,
4282                            !(res = __follow_pte_pmd(mm, address, NULL, NULL,
4283                                                     ptepp, NULL, ptlp)));
4284         return res;
4285 }
4286 
4287 int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4288                              unsigned long *start, unsigned long *end,
4289                              pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4290 {
4291         int res;
4292 
4293         /* (void) is needed to make gcc happy */
4294         (void) __cond_lock(*ptlp,
4295                            !(res = __follow_pte_pmd(mm, address, start, end,
4296                                                     ptepp, pmdpp, ptlp)));
4297         return res;
4298 }
4299 EXPORT_SYMBOL(follow_pte_pmd);
4300 
4301 /**
4302  * follow_pfn - look up PFN at a user virtual address
4303  * @vma: memory mapping
4304  * @address: user virtual address
4305  * @pfn: location to store found PFN
4306  *
4307  * Only IO mappings and raw PFN mappings are allowed.
4308  *
4309  * Returns zero and the pfn at @pfn on success, -ve otherwise.
4310  */
4311 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4312         unsigned long *pfn)
4313 {
4314         int ret = -EINVAL;
4315         spinlock_t *ptl;
4316         pte_t *ptep;
4317 
4318         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4319                 return ret;
4320 
4321         ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4322         if (ret)
4323                 return ret;
4324         *pfn = pte_pfn(*ptep);
4325         pte_unmap_unlock(ptep, ptl);
4326         return 0;
4327 }
4328 EXPORT_SYMBOL(follow_pfn);
4329 
4330 #ifdef CONFIG_HAVE_IOREMAP_PROT
4331 int follow_phys(struct vm_area_struct *vma,
4332                 unsigned long address, unsigned int flags,
4333                 unsigned long *prot, resource_size_t *phys)
4334 {
4335         int ret = -EINVAL;
4336         pte_t *ptep, pte;
4337         spinlock_t *ptl;
4338 
4339         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4340                 goto out;
4341 
4342         if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4343                 goto out;
4344         pte = *ptep;
4345 
4346         if ((flags & FOLL_WRITE) && !pte_write(pte))
4347                 goto unlock;
4348 
4349         *prot = pgprot_val(pte_pgprot(pte));
4350         *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4351 
4352         ret = 0;
4353 unlock:
4354         pte_unmap_unlock(ptep, ptl);
4355 out:
4356         return ret;
4357 }
4358 
4359 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4360                         void *buf, int len, int write)
4361 {
4362         resource_size_t phys_addr;
4363         unsigned long prot = 0;
4364         void __iomem *maddr;
4365         int offset = addr & (PAGE_SIZE-1);
4366 
4367         if (follow_phys(vma, addr, write, &prot, &phys_addr))
4368                 return -EINVAL;
4369 
4370         maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4371         if (write)
4372                 memcpy_toio(maddr + offset, buf, len);
4373         else
4374                 memcpy_fromio(buf, maddr + offset, len);
4375         iounmap(maddr);
4376 
4377         return len;
4378 }
4379 EXPORT_SYMBOL_GPL(generic_access_phys);
4380 #endif
4381 
4382 /*
4383  * Access another process' address space as given in mm.  If non-NULL, use the
4384  * given task for page fault accounting.
4385  */
4386 int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4387                 unsigned long addr, void *buf, int len, unsigned int gup_flags)
4388 {
4389         struct vm_area_struct *vma;
4390         void *old_buf = buf;
4391         int write = gup_flags & FOLL_WRITE;
4392 
4393         down_read(&mm->mmap_sem);
4394         /* ignore errors, just check how much was successfully transferred */
4395         while (len) {
4396                 int bytes, ret, offset;
4397                 void *maddr;
4398                 struct page *page = NULL;
4399 
4400                 ret = get_user_pages_remote(tsk, mm, addr, 1,
4401                                 gup_flags, &page, &vma, NULL);
4402                 if (ret <= 0) {
4403 #ifndef CONFIG_HAVE_IOREMAP_PROT
4404                         break;
4405 #else
4406                         /*
4407                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
4408                          * we can access using slightly different code.
4409                          */
4410                         vma = find_vma(mm, addr);
4411                         if (!vma || vma->vm_start > addr)
4412                                 break;
4413                         if (vma->vm_ops && vma->vm_ops->access)
4414                                 ret = vma->vm_ops->access(vma, addr, buf,
4415                                                           len, write);
4416                         if (ret <= 0)
4417                                 break;
4418                         bytes = ret;
4419 #endif
4420                 } else {
4421                         bytes = len;
4422                         offset = addr & (PAGE_SIZE-1);
4423                         if (bytes > PAGE_SIZE-offset)
4424                                 bytes = PAGE_SIZE-offset;
4425 
4426                         maddr = kmap(page);
4427                         if (write) {
4428                                 copy_to_user_page(vma, page, addr,
4429                                                   maddr + offset, buf, bytes);
4430                                 set_page_dirty_lock(page);
4431                         } else {
4432                                 copy_from_user_page(vma, page, addr,
4433                                                     buf, maddr + offset, bytes);
4434                         }
4435                         kunmap(page);
4436                         put_page(page);
4437                 }
4438                 len -= bytes;
4439                 buf += bytes;
4440                 addr += bytes;
4441         }
4442         up_read(&mm->mmap_sem);
4443 
4444         return buf - old_buf;
4445 }
4446 
4447 /**
4448  * access_remote_vm - access another process' address space
4449  * @mm:         the mm_struct of the target address space
4450  * @addr:       start address to access
4451  * @buf:        source or destination buffer
4452  * @len:        number of bytes to transfer
4453  * @gup_flags:  flags modifying lookup behaviour
4454  *
4455  * The caller must hold a reference on @mm.
4456  */
4457 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4458                 void *buf, int len, unsigned int gup_flags)
4459 {
4460         return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4461 }
4462 
4463 /*
4464  * Access another process' address space.
4465  * Source/target buffer must be kernel space,
4466  * Do not walk the page table directly, use get_user_pages
4467  */
4468 int access_process_vm(struct task_struct *tsk, unsigned long addr,
4469                 void *buf, int len, unsigned int gup_flags)
4470 {
4471         struct mm_struct *mm;
4472         int ret;
4473 
4474         mm = get_task_mm(tsk);
4475         if (!mm)
4476                 return 0;
4477 
4478         ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4479 
4480         mmput(mm);
4481 
4482         return ret;
4483 }
4484 EXPORT_SYMBOL_GPL(access_process_vm);
4485 
4486 /*
4487  * Print the name of a VMA.
4488  */
4489 void print_vma_addr(char *prefix, unsigned long ip)
4490 {
4491         struct mm_struct *mm = current->mm;
4492         struct vm_area_struct *vma;
4493 
4494         /*
4495          * we might be running from an atomic context so we cannot sleep
4496          */
4497         if (!down_read_trylock(&mm->mmap_sem))
4498                 return;
4499 
4500         vma = find_vma(mm, ip);
4501         if (vma && vma->vm_file) {
4502                 struct file *f = vma->vm_file;
4503                 char *buf = (char *)__get_free_page(GFP_NOWAIT);
4504                 if (buf) {
4505                         char *p;
4506 
4507                         p = file_path(f, buf, PAGE_SIZE);
4508                         if (IS_ERR(p))
4509                                 p = "?";
4510                         printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4511                                         vma->vm_start,
4512                                         vma->vm_end - vma->vm_start);
4513                         free_page((unsigned long)buf);
4514                 }
4515         }
4516         up_read(&mm->mmap_sem);
4517 }
4518 
4519 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4520 void __might_fault(const char *file, int line)
4521 {
4522         /*
4523          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4524          * holding the mmap_sem, this is safe because kernel memory doesn't
4525          * get paged out, therefore we'll never actually fault, and the
4526          * below annotations will generate false positives.
4527          */
4528         if (uaccess_kernel())
4529                 return;
4530         if (pagefault_disabled())
4531                 return;
4532         __might_sleep(file, line, 0);
4533 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4534         if (current->mm)
4535                 might_lock_read(&current->mm->mmap_sem);
4536 #endif
4537 }
4538 EXPORT_SYMBOL(__might_fault);
4539 #endif
4540 
4541 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4542 static void clear_gigantic_page(struct page *page,
4543                                 unsigned long addr,
4544                                 unsigned int pages_per_huge_page)
4545 {
4546         int i;
4547         struct page *p = page;
4548 
4549         might_sleep();
4550         for (i = 0; i < pages_per_huge_page;
4551              i++, p = mem_map_next(p, page, i)) {
4552                 cond_resched();
4553                 clear_user_highpage(p, addr + i * PAGE_SIZE);
4554         }
4555 }
4556 void clear_huge_page(struct page *page,
4557                      unsigned long addr_hint, unsigned int pages_per_huge_page)
4558 {
4559         int i, n, base, l;
4560         unsigned long addr = addr_hint &
4561                 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4562 
4563         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4564                 clear_gigantic_page(page, addr, pages_per_huge_page);
4565                 return;
4566         }
4567 
4568         /* Clear sub-page to access last to keep its cache lines hot */
4569         might_sleep();
4570         n = (addr_hint - addr) / PAGE_SIZE;
4571         if (2 * n <= pages_per_huge_page) {
4572                 /* If sub-page to access in first half of huge page */
4573                 base = 0;
4574                 l = n;
4575                 /* Clear sub-pages at the end of huge page */
4576                 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
4577                         cond_resched();
4578                         clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4579                 }
4580         } else {
4581                 /* If sub-page to access in second half of huge page */
4582                 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
4583                 l = pages_per_huge_page - n;
4584                 /* Clear sub-pages at the begin of huge page */
4585                 for (i = 0; i < base; i++) {
4586                         cond_resched();
4587                         clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4588                 }
4589         }
4590         /*
4591          * Clear remaining sub-pages in left-right-left-right pattern
4592          * towards the sub-page to access
4593          */
4594         for (i = 0; i < l; i++) {
4595                 int left_idx = base + i;
4596                 int right_idx = base + 2 * l - 1 - i;
4597 
4598                 cond_resched();
4599                 clear_user_highpage(page + left_idx,
4600                                     addr + left_idx * PAGE_SIZE);
4601                 cond_resched();
4602                 clear_user_highpage(page + right_idx,
4603                                     addr + right_idx * PAGE_SIZE);
4604         }
4605 }
4606 
4607 static void copy_user_gigantic_page(struct page *dst, struct page *src,
4608                                     unsigned long addr,
4609                                     struct vm_area_struct *vma,
4610                                     unsigned int pages_per_huge_page)
4611 {
4612         int i;
4613         struct page *dst_base = dst;
4614         struct page *src_base = src;
4615 
4616         for (i = 0; i < pages_per_huge_page; ) {
4617                 cond_resched();
4618                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4619 
4620                 i++;
4621                 dst = mem_map_next(dst, dst_base, i);
4622                 src = mem_map_next(src, src_base, i);
4623         }
4624 }
4625 
4626 void copy_user_huge_page(struct page *dst, struct page *src,
4627                          unsigned long addr, struct vm_area_struct *vma,
4628                          unsigned int pages_per_huge_page)
4629 {
4630         int i;
4631 
4632         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4633                 copy_user_gigantic_page(dst, src, addr, vma,
4634                                         pages_per_huge_page);
4635                 return;
4636         }
4637 
4638         might_sleep();
4639         for (i = 0; i < pages_per_huge_page; i++) {
4640                 cond_resched();
4641                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4642         }
4643 }
4644 
4645 long copy_huge_page_from_user(struct page *dst_page,
4646                                 const void __user *usr_src,
4647                                 unsigned int pages_per_huge_page,
4648                                 bool allow_pagefault)
4649 {
4650         void *src = (void *)usr_src;
4651         void *page_kaddr;
4652         unsigned long i, rc = 0;
4653         unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4654 
4655         for (i = 0; i < pages_per_huge_page; i++) {
4656                 if (allow_pagefault)
4657                         page_kaddr = kmap(dst_page + i);
4658                 else
4659                         page_kaddr = kmap_atomic(dst_page + i);
4660                 rc = copy_from_user(page_kaddr,
4661                                 (const void __user *)(src + i * PAGE_SIZE),
4662                                 PAGE_SIZE);
4663                 if (allow_pagefault)
4664                         kunmap(dst_page + i);
4665                 else
4666                         kunmap_atomic(page_kaddr);
4667 
4668                 ret_val -= (PAGE_SIZE - rc);
4669                 if (rc)
4670                         break;
4671 
4672                 cond_resched();
4673         }
4674         return ret_val;
4675 }
4676 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4677 
4678 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4679 
4680 static struct kmem_cache *page_ptl_cachep;
4681 
4682 void __init ptlock_cache_init(void)
4683 {
4684         page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4685                         SLAB_PANIC, NULL);
4686 }
4687 
4688 bool ptlock_alloc(struct page *page)
4689 {
4690         spinlock_t *ptl;
4691 
4692         ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4693         if (!ptl)
4694                 return false;
4695         page->ptl = ptl;
4696         return true;
4697 }
4698 
4699 void ptlock_free(struct page *page)
4700 {
4701         kmem_cache_free(page_ptl_cachep, page->ptl);
4702 }
4703 #endif
4704 

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