1 /*
2 * Copyright (C) 2009 Red Hat, Inc.
3 *
4 * This work is licensed under the terms of the GNU GPL, version 2. See
5 * the COPYING file in the top-level directory.
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/mm.h>
11 #include <linux/sched.h>
12 #include <linux/sched/coredump.h>
13 #include <linux/sched/numa_balancing.h>
14 #include <linux/highmem.h>
15 #include <linux/hugetlb.h>
16 #include <linux/mmu_notifier.h>
17 #include <linux/rmap.h>
18 #include <linux/swap.h>
19 #include <linux/shrinker.h>
20 #include <linux/mm_inline.h>
21 #include <linux/swapops.h>
22 #include <linux/dax.h>
23 #include <linux/khugepaged.h>
24 #include <linux/freezer.h>
25 #include <linux/pfn_t.h>
26 #include <linux/mman.h>
27 #include <linux/memremap.h>
28 #include <linux/pagemap.h>
29 #include <linux/debugfs.h>
30 #include <linux/migrate.h>
31 #include <linux/hashtable.h>
32 #include <linux/userfaultfd_k.h>
33 #include <linux/page_idle.h>
34 #include <linux/shmem_fs.h>
35 #include <linux/oom.h>
36
37 #include <asm/tlb.h>
38 #include <asm/pgalloc.h>
39 #include "internal.h"
40
41 /*
42 * By default, transparent hugepage support is disabled in order to avoid
43 * risking an increased memory footprint for applications that are not
44 * guaranteed to benefit from it. When transparent hugepage support is
45 * enabled, it is for all mappings, and khugepaged scans all mappings.
46 * Defrag is invoked by khugepaged hugepage allocations and by page faults
47 * for all hugepage allocations.
48 */
49 unsigned long transparent_hugepage_flags __read_mostly =
50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
51 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
52 #endif
53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
55 #endif
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
59
60 static struct shrinker deferred_split_shrinker;
61
62 static atomic_t huge_zero_refcount;
63 struct page *huge_zero_page __read_mostly;
64
65 bool transparent_hugepage_enabled(struct vm_area_struct *vma)
66 {
67 if (vma_is_anonymous(vma))
68 return __transparent_hugepage_enabled(vma);
69 if (vma_is_shmem(vma) && shmem_huge_enabled(vma))
70 return __transparent_hugepage_enabled(vma);
71
72 return false;
73 }
74
75 static struct page *get_huge_zero_page(void)
76 {
77 struct page *zero_page;
78 retry:
79 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
80 return READ_ONCE(huge_zero_page);
81
82 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
83 HPAGE_PMD_ORDER);
84 if (!zero_page) {
85 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
86 return NULL;
87 }
88 count_vm_event(THP_ZERO_PAGE_ALLOC);
89 preempt_disable();
90 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
91 preempt_enable();
92 __free_pages(zero_page, compound_order(zero_page));
93 goto retry;
94 }
95
96 /* We take additional reference here. It will be put back by shrinker */
97 atomic_set(&huge_zero_refcount, 2);
98 preempt_enable();
99 return READ_ONCE(huge_zero_page);
100 }
101
102 static void put_huge_zero_page(void)
103 {
104 /*
105 * Counter should never go to zero here. Only shrinker can put
106 * last reference.
107 */
108 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
109 }
110
111 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
112 {
113 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
114 return READ_ONCE(huge_zero_page);
115
116 if (!get_huge_zero_page())
117 return NULL;
118
119 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
120 put_huge_zero_page();
121
122 return READ_ONCE(huge_zero_page);
123 }
124
125 void mm_put_huge_zero_page(struct mm_struct *mm)
126 {
127 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
128 put_huge_zero_page();
129 }
130
131 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
132 struct shrink_control *sc)
133 {
134 /* we can free zero page only if last reference remains */
135 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
136 }
137
138 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
139 struct shrink_control *sc)
140 {
141 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
142 struct page *zero_page = xchg(&huge_zero_page, NULL);
143 BUG_ON(zero_page == NULL);
144 __free_pages(zero_page, compound_order(zero_page));
145 return HPAGE_PMD_NR;
146 }
147
148 return 0;
149 }
150
151 static struct shrinker huge_zero_page_shrinker = {
152 .count_objects = shrink_huge_zero_page_count,
153 .scan_objects = shrink_huge_zero_page_scan,
154 .seeks = DEFAULT_SEEKS,
155 };
156
157 #ifdef CONFIG_SYSFS
158 static ssize_t enabled_show(struct kobject *kobj,
159 struct kobj_attribute *attr, char *buf)
160 {
161 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
162 return sprintf(buf, "[always] madvise never\n");
163 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
164 return sprintf(buf, "always [madvise] never\n");
165 else
166 return sprintf(buf, "always madvise [never]\n");
167 }
168
169 static ssize_t enabled_store(struct kobject *kobj,
170 struct kobj_attribute *attr,
171 const char *buf, size_t count)
172 {
173 ssize_t ret = count;
174
175 if (!memcmp("always", buf,
176 min(sizeof("always")-1, count))) {
177 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
178 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
179 } else if (!memcmp("madvise", buf,
180 min(sizeof("madvise")-1, count))) {
181 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
182 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
183 } else if (!memcmp("never", buf,
184 min(sizeof("never")-1, count))) {
185 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
186 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
187 } else
188 ret = -EINVAL;
189
190 if (ret > 0) {
191 int err = start_stop_khugepaged();
192 if (err)
193 ret = err;
194 }
195 return ret;
196 }
197 static struct kobj_attribute enabled_attr =
198 __ATTR(enabled, 0644, enabled_show, enabled_store);
199
200 ssize_t single_hugepage_flag_show(struct kobject *kobj,
201 struct kobj_attribute *attr, char *buf,
202 enum transparent_hugepage_flag flag)
203 {
204 return sprintf(buf, "%d\n",
205 !!test_bit(flag, &transparent_hugepage_flags));
206 }
207
208 ssize_t single_hugepage_flag_store(struct kobject *kobj,
209 struct kobj_attribute *attr,
210 const char *buf, size_t count,
211 enum transparent_hugepage_flag flag)
212 {
213 unsigned long value;
214 int ret;
215
216 ret = kstrtoul(buf, 10, &value);
217 if (ret < 0)
218 return ret;
219 if (value > 1)
220 return -EINVAL;
221
222 if (value)
223 set_bit(flag, &transparent_hugepage_flags);
224 else
225 clear_bit(flag, &transparent_hugepage_flags);
226
227 return count;
228 }
229
230 static ssize_t defrag_show(struct kobject *kobj,
231 struct kobj_attribute *attr, char *buf)
232 {
233 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
234 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
235 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
236 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
237 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
238 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
239 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
240 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
241 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
242 }
243
244 static ssize_t defrag_store(struct kobject *kobj,
245 struct kobj_attribute *attr,
246 const char *buf, size_t count)
247 {
248 if (!memcmp("always", buf,
249 min(sizeof("always")-1, count))) {
250 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
251 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
253 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
254 } else if (!memcmp("defer+madvise", buf,
255 min(sizeof("defer+madvise")-1, count))) {
256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
259 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
260 } else if (!memcmp("defer", buf,
261 min(sizeof("defer")-1, count))) {
262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
264 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
265 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
266 } else if (!memcmp("madvise", buf,
267 min(sizeof("madvise")-1, count))) {
268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
270 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
271 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
272 } else if (!memcmp("never", buf,
273 min(sizeof("never")-1, count))) {
274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
276 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
277 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
278 } else
279 return -EINVAL;
280
281 return count;
282 }
283 static struct kobj_attribute defrag_attr =
284 __ATTR(defrag, 0644, defrag_show, defrag_store);
285
286 static ssize_t use_zero_page_show(struct kobject *kobj,
287 struct kobj_attribute *attr, char *buf)
288 {
289 return single_hugepage_flag_show(kobj, attr, buf,
290 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
291 }
292 static ssize_t use_zero_page_store(struct kobject *kobj,
293 struct kobj_attribute *attr, const char *buf, size_t count)
294 {
295 return single_hugepage_flag_store(kobj, attr, buf, count,
296 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
297 }
298 static struct kobj_attribute use_zero_page_attr =
299 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
300
301 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
302 struct kobj_attribute *attr, char *buf)
303 {
304 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
305 }
306 static struct kobj_attribute hpage_pmd_size_attr =
307 __ATTR_RO(hpage_pmd_size);
308
309 #ifdef CONFIG_DEBUG_VM
310 static ssize_t debug_cow_show(struct kobject *kobj,
311 struct kobj_attribute *attr, char *buf)
312 {
313 return single_hugepage_flag_show(kobj, attr, buf,
314 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
315 }
316 static ssize_t debug_cow_store(struct kobject *kobj,
317 struct kobj_attribute *attr,
318 const char *buf, size_t count)
319 {
320 return single_hugepage_flag_store(kobj, attr, buf, count,
321 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
322 }
323 static struct kobj_attribute debug_cow_attr =
324 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
325 #endif /* CONFIG_DEBUG_VM */
326
327 static struct attribute *hugepage_attr[] = {
328 &enabled_attr.attr,
329 &defrag_attr.attr,
330 &use_zero_page_attr.attr,
331 &hpage_pmd_size_attr.attr,
332 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
333 &shmem_enabled_attr.attr,
334 #endif
335 #ifdef CONFIG_DEBUG_VM
336 &debug_cow_attr.attr,
337 #endif
338 NULL,
339 };
340
341 static const struct attribute_group hugepage_attr_group = {
342 .attrs = hugepage_attr,
343 };
344
345 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
346 {
347 int err;
348
349 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
350 if (unlikely(!*hugepage_kobj)) {
351 pr_err("failed to create transparent hugepage kobject\n");
352 return -ENOMEM;
353 }
354
355 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
356 if (err) {
357 pr_err("failed to register transparent hugepage group\n");
358 goto delete_obj;
359 }
360
361 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
362 if (err) {
363 pr_err("failed to register transparent hugepage group\n");
364 goto remove_hp_group;
365 }
366
367 return 0;
368
369 remove_hp_group:
370 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
371 delete_obj:
372 kobject_put(*hugepage_kobj);
373 return err;
374 }
375
376 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
377 {
378 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
379 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
380 kobject_put(hugepage_kobj);
381 }
382 #else
383 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
384 {
385 return 0;
386 }
387
388 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
389 {
390 }
391 #endif /* CONFIG_SYSFS */
392
393 static int __init hugepage_init(void)
394 {
395 int err;
396 struct kobject *hugepage_kobj;
397
398 if (!has_transparent_hugepage()) {
399 transparent_hugepage_flags = 0;
400 return -EINVAL;
401 }
402
403 /*
404 * hugepages can't be allocated by the buddy allocator
405 */
406 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
407 /*
408 * we use page->mapping and page->index in second tail page
409 * as list_head: assuming THP order >= 2
410 */
411 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
412
413 err = hugepage_init_sysfs(&hugepage_kobj);
414 if (err)
415 goto err_sysfs;
416
417 err = khugepaged_init();
418 if (err)
419 goto err_slab;
420
421 err = register_shrinker(&huge_zero_page_shrinker);
422 if (err)
423 goto err_hzp_shrinker;
424 err = register_shrinker(&deferred_split_shrinker);
425 if (err)
426 goto err_split_shrinker;
427
428 /*
429 * By default disable transparent hugepages on smaller systems,
430 * where the extra memory used could hurt more than TLB overhead
431 * is likely to save. The admin can still enable it through /sys.
432 */
433 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
434 transparent_hugepage_flags = 0;
435 return 0;
436 }
437
438 err = start_stop_khugepaged();
439 if (err)
440 goto err_khugepaged;
441
442 return 0;
443 err_khugepaged:
444 unregister_shrinker(&deferred_split_shrinker);
445 err_split_shrinker:
446 unregister_shrinker(&huge_zero_page_shrinker);
447 err_hzp_shrinker:
448 khugepaged_destroy();
449 err_slab:
450 hugepage_exit_sysfs(hugepage_kobj);
451 err_sysfs:
452 return err;
453 }
454 subsys_initcall(hugepage_init);
455
456 static int __init setup_transparent_hugepage(char *str)
457 {
458 int ret = 0;
459 if (!str)
460 goto out;
461 if (!strcmp(str, "always")) {
462 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
463 &transparent_hugepage_flags);
464 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
465 &transparent_hugepage_flags);
466 ret = 1;
467 } else if (!strcmp(str, "madvise")) {
468 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
469 &transparent_hugepage_flags);
470 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
471 &transparent_hugepage_flags);
472 ret = 1;
473 } else if (!strcmp(str, "never")) {
474 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
475 &transparent_hugepage_flags);
476 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
477 &transparent_hugepage_flags);
478 ret = 1;
479 }
480 out:
481 if (!ret)
482 pr_warn("transparent_hugepage= cannot parse, ignored\n");
483 return ret;
484 }
485 __setup("transparent_hugepage=", setup_transparent_hugepage);
486
487 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
488 {
489 if (likely(vma->vm_flags & VM_WRITE))
490 pmd = pmd_mkwrite(pmd);
491 return pmd;
492 }
493
494 static inline struct list_head *page_deferred_list(struct page *page)
495 {
496 /* ->lru in the tail pages is occupied by compound_head. */
497 return &page[2].deferred_list;
498 }
499
500 void prep_transhuge_page(struct page *page)
501 {
502 /*
503 * we use page->mapping and page->indexlru in second tail page
504 * as list_head: assuming THP order >= 2
505 */
506
507 INIT_LIST_HEAD(page_deferred_list(page));
508 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
509 }
510
511 unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
512 loff_t off, unsigned long flags, unsigned long size)
513 {
514 unsigned long addr;
515 loff_t off_end = off + len;
516 loff_t off_align = round_up(off, size);
517 unsigned long len_pad;
518
519 if (off_end <= off_align || (off_end - off_align) < size)
520 return 0;
521
522 len_pad = len + size;
523 if (len_pad < len || (off + len_pad) < off)
524 return 0;
525
526 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
527 off >> PAGE_SHIFT, flags);
528 if (IS_ERR_VALUE(addr))
529 return 0;
530
531 addr += (off - addr) & (size - 1);
532 return addr;
533 }
534
535 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
536 unsigned long len, unsigned long pgoff, unsigned long flags)
537 {
538 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
539
540 if (addr)
541 goto out;
542 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
543 goto out;
544
545 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
546 if (addr)
547 return addr;
548
549 out:
550 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
551 }
552 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
553
554 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
555 struct page *page, gfp_t gfp)
556 {
557 struct vm_area_struct *vma = vmf->vma;
558 struct mem_cgroup *memcg;
559 pgtable_t pgtable;
560 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
561 vm_fault_t ret = 0;
562
563 VM_BUG_ON_PAGE(!PageCompound(page), page);
564
565 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
566 put_page(page);
567 count_vm_event(THP_FAULT_FALLBACK);
568 return VM_FAULT_FALLBACK;
569 }
570
571 pgtable = pte_alloc_one(vma->vm_mm);
572 if (unlikely(!pgtable)) {
573 ret = VM_FAULT_OOM;
574 goto release;
575 }
576
577 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
578 /*
579 * The memory barrier inside __SetPageUptodate makes sure that
580 * clear_huge_page writes become visible before the set_pmd_at()
581 * write.
582 */
583 __SetPageUptodate(page);
584
585 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
586 if (unlikely(!pmd_none(*vmf->pmd))) {
587 goto unlock_release;
588 } else {
589 pmd_t entry;
590
591 ret = check_stable_address_space(vma->vm_mm);
592 if (ret)
593 goto unlock_release;
594
595 /* Deliver the page fault to userland */
596 if (userfaultfd_missing(vma)) {
597 vm_fault_t ret2;
598
599 spin_unlock(vmf->ptl);
600 mem_cgroup_cancel_charge(page, memcg, true);
601 put_page(page);
602 pte_free(vma->vm_mm, pgtable);
603 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
604 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
605 return ret2;
606 }
607
608 entry = mk_huge_pmd(page, vma->vm_page_prot);
609 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
610 page_add_new_anon_rmap(page, vma, haddr, true);
611 mem_cgroup_commit_charge(page, memcg, false, true);
612 lru_cache_add_active_or_unevictable(page, vma);
613 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
614 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
615 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
616 mm_inc_nr_ptes(vma->vm_mm);
617 spin_unlock(vmf->ptl);
618 count_vm_event(THP_FAULT_ALLOC);
619 }
620
621 return 0;
622 unlock_release:
623 spin_unlock(vmf->ptl);
624 release:
625 if (pgtable)
626 pte_free(vma->vm_mm, pgtable);
627 mem_cgroup_cancel_charge(page, memcg, true);
628 put_page(page);
629 return ret;
630
631 }
632
633 /*
634 * always: directly stall for all thp allocations
635 * defer: wake kswapd and fail if not immediately available
636 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
637 * fail if not immediately available
638 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
639 * available
640 * never: never stall for any thp allocation
641 */
642 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
643 {
644 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
645
646 /* Always do synchronous compaction */
647 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
648 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
649
650 /* Kick kcompactd and fail quickly */
651 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
652 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
653
654 /* Synchronous compaction if madvised, otherwise kick kcompactd */
655 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
656 return GFP_TRANSHUGE_LIGHT |
657 (vma_madvised ? __GFP_DIRECT_RECLAIM :
658 __GFP_KSWAPD_RECLAIM);
659
660 /* Only do synchronous compaction if madvised */
661 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
662 return GFP_TRANSHUGE_LIGHT |
663 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
664
665 return GFP_TRANSHUGE_LIGHT;
666 }
667
668 /* Caller must hold page table lock. */
669 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
670 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
671 struct page *zero_page)
672 {
673 pmd_t entry;
674 if (!pmd_none(*pmd))
675 return false;
676 entry = mk_pmd(zero_page, vma->vm_page_prot);
677 entry = pmd_mkhuge(entry);
678 if (pgtable)
679 pgtable_trans_huge_deposit(mm, pmd, pgtable);
680 set_pmd_at(mm, haddr, pmd, entry);
681 mm_inc_nr_ptes(mm);
682 return true;
683 }
684
685 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
686 {
687 struct vm_area_struct *vma = vmf->vma;
688 gfp_t gfp;
689 struct page *page;
690 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
691
692 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
693 return VM_FAULT_FALLBACK;
694 if (unlikely(anon_vma_prepare(vma)))
695 return VM_FAULT_OOM;
696 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
697 return VM_FAULT_OOM;
698 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
699 !mm_forbids_zeropage(vma->vm_mm) &&
700 transparent_hugepage_use_zero_page()) {
701 pgtable_t pgtable;
702 struct page *zero_page;
703 bool set;
704 vm_fault_t ret;
705 pgtable = pte_alloc_one(vma->vm_mm);
706 if (unlikely(!pgtable))
707 return VM_FAULT_OOM;
708 zero_page = mm_get_huge_zero_page(vma->vm_mm);
709 if (unlikely(!zero_page)) {
710 pte_free(vma->vm_mm, pgtable);
711 count_vm_event(THP_FAULT_FALLBACK);
712 return VM_FAULT_FALLBACK;
713 }
714 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
715 ret = 0;
716 set = false;
717 if (pmd_none(*vmf->pmd)) {
718 ret = check_stable_address_space(vma->vm_mm);
719 if (ret) {
720 spin_unlock(vmf->ptl);
721 } else if (userfaultfd_missing(vma)) {
722 spin_unlock(vmf->ptl);
723 ret = handle_userfault(vmf, VM_UFFD_MISSING);
724 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
725 } else {
726 set_huge_zero_page(pgtable, vma->vm_mm, vma,
727 haddr, vmf->pmd, zero_page);
728 spin_unlock(vmf->ptl);
729 set = true;
730 }
731 } else
732 spin_unlock(vmf->ptl);
733 if (!set)
734 pte_free(vma->vm_mm, pgtable);
735 return ret;
736 }
737 gfp = alloc_hugepage_direct_gfpmask(vma);
738 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
739 if (unlikely(!page)) {
740 count_vm_event(THP_FAULT_FALLBACK);
741 return VM_FAULT_FALLBACK;
742 }
743 prep_transhuge_page(page);
744 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
745 }
746
747 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
748 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
749 pgtable_t pgtable)
750 {
751 struct mm_struct *mm = vma->vm_mm;
752 pmd_t entry;
753 spinlock_t *ptl;
754
755 ptl = pmd_lock(mm, pmd);
756 if (!pmd_none(*pmd)) {
757 if (write) {
758 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
759 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
760 goto out_unlock;
761 }
762 entry = pmd_mkyoung(*pmd);
763 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
764 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
765 update_mmu_cache_pmd(vma, addr, pmd);
766 }
767
768 goto out_unlock;
769 }
770
771 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
772 if (pfn_t_devmap(pfn))
773 entry = pmd_mkdevmap(entry);
774 if (write) {
775 entry = pmd_mkyoung(pmd_mkdirty(entry));
776 entry = maybe_pmd_mkwrite(entry, vma);
777 }
778
779 if (pgtable) {
780 pgtable_trans_huge_deposit(mm, pmd, pgtable);
781 mm_inc_nr_ptes(mm);
782 pgtable = NULL;
783 }
784
785 set_pmd_at(mm, addr, pmd, entry);
786 update_mmu_cache_pmd(vma, addr, pmd);
787
788 out_unlock:
789 spin_unlock(ptl);
790 if (pgtable)
791 pte_free(mm, pgtable);
792 }
793
794 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
795 {
796 unsigned long addr = vmf->address & PMD_MASK;
797 struct vm_area_struct *vma = vmf->vma;
798 pgprot_t pgprot = vma->vm_page_prot;
799 pgtable_t pgtable = NULL;
800
801 /*
802 * If we had pmd_special, we could avoid all these restrictions,
803 * but we need to be consistent with PTEs and architectures that
804 * can't support a 'special' bit.
805 */
806 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
807 !pfn_t_devmap(pfn));
808 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
809 (VM_PFNMAP|VM_MIXEDMAP));
810 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
811
812 if (addr < vma->vm_start || addr >= vma->vm_end)
813 return VM_FAULT_SIGBUS;
814
815 if (arch_needs_pgtable_deposit()) {
816 pgtable = pte_alloc_one(vma->vm_mm);
817 if (!pgtable)
818 return VM_FAULT_OOM;
819 }
820
821 track_pfn_insert(vma, &pgprot, pfn);
822
823 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
824 return VM_FAULT_NOPAGE;
825 }
826 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
827
828 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
829 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
830 {
831 if (likely(vma->vm_flags & VM_WRITE))
832 pud = pud_mkwrite(pud);
833 return pud;
834 }
835
836 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
837 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
838 {
839 struct mm_struct *mm = vma->vm_mm;
840 pud_t entry;
841 spinlock_t *ptl;
842
843 ptl = pud_lock(mm, pud);
844 if (!pud_none(*pud)) {
845 if (write) {
846 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
847 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
848 goto out_unlock;
849 }
850 entry = pud_mkyoung(*pud);
851 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
852 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
853 update_mmu_cache_pud(vma, addr, pud);
854 }
855 goto out_unlock;
856 }
857
858 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
859 if (pfn_t_devmap(pfn))
860 entry = pud_mkdevmap(entry);
861 if (write) {
862 entry = pud_mkyoung(pud_mkdirty(entry));
863 entry = maybe_pud_mkwrite(entry, vma);
864 }
865 set_pud_at(mm, addr, pud, entry);
866 update_mmu_cache_pud(vma, addr, pud);
867
868 out_unlock:
869 spin_unlock(ptl);
870 }
871
872 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
873 {
874 unsigned long addr = vmf->address & PUD_MASK;
875 struct vm_area_struct *vma = vmf->vma;
876 pgprot_t pgprot = vma->vm_page_prot;
877
878 /*
879 * If we had pud_special, we could avoid all these restrictions,
880 * but we need to be consistent with PTEs and architectures that
881 * can't support a 'special' bit.
882 */
883 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
884 !pfn_t_devmap(pfn));
885 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
886 (VM_PFNMAP|VM_MIXEDMAP));
887 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
888
889 if (addr < vma->vm_start || addr >= vma->vm_end)
890 return VM_FAULT_SIGBUS;
891
892 track_pfn_insert(vma, &pgprot, pfn);
893
894 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
895 return VM_FAULT_NOPAGE;
896 }
897 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
898 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
899
900 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
901 pmd_t *pmd, int flags)
902 {
903 pmd_t _pmd;
904
905 _pmd = pmd_mkyoung(*pmd);
906 if (flags & FOLL_WRITE)
907 _pmd = pmd_mkdirty(_pmd);
908 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
909 pmd, _pmd, flags & FOLL_WRITE))
910 update_mmu_cache_pmd(vma, addr, pmd);
911 }
912
913 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
914 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
915 {
916 unsigned long pfn = pmd_pfn(*pmd);
917 struct mm_struct *mm = vma->vm_mm;
918 struct page *page;
919
920 assert_spin_locked(pmd_lockptr(mm, pmd));
921
922 /*
923 * When we COW a devmap PMD entry, we split it into PTEs, so we should
924 * not be in this function with `flags & FOLL_COW` set.
925 */
926 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
927
928 if (flags & FOLL_WRITE && !pmd_write(*pmd))
929 return NULL;
930
931 if (pmd_present(*pmd) && pmd_devmap(*pmd))
932 /* pass */;
933 else
934 return NULL;
935
936 if (flags & FOLL_TOUCH)
937 touch_pmd(vma, addr, pmd, flags);
938
939 /*
940 * device mapped pages can only be returned if the
941 * caller will manage the page reference count.
942 */
943 if (!(flags & FOLL_GET))
944 return ERR_PTR(-EEXIST);
945
946 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
947 *pgmap = get_dev_pagemap(pfn, *pgmap);
948 if (!*pgmap)
949 return ERR_PTR(-EFAULT);
950 page = pfn_to_page(pfn);
951 get_page(page);
952
953 return page;
954 }
955
956 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
957 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
958 struct vm_area_struct *vma)
959 {
960 spinlock_t *dst_ptl, *src_ptl;
961 struct page *src_page;
962 pmd_t pmd;
963 pgtable_t pgtable = NULL;
964 int ret = -ENOMEM;
965
966 /* Skip if can be re-fill on fault */
967 if (!vma_is_anonymous(vma))
968 return 0;
969
970 pgtable = pte_alloc_one(dst_mm);
971 if (unlikely(!pgtable))
972 goto out;
973
974 dst_ptl = pmd_lock(dst_mm, dst_pmd);
975 src_ptl = pmd_lockptr(src_mm, src_pmd);
976 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
977
978 ret = -EAGAIN;
979 pmd = *src_pmd;
980
981 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
982 if (unlikely(is_swap_pmd(pmd))) {
983 swp_entry_t entry = pmd_to_swp_entry(pmd);
984
985 VM_BUG_ON(!is_pmd_migration_entry(pmd));
986 if (is_write_migration_entry(entry)) {
987 make_migration_entry_read(&entry);
988 pmd = swp_entry_to_pmd(entry);
989 if (pmd_swp_soft_dirty(*src_pmd))
990 pmd = pmd_swp_mksoft_dirty(pmd);
991 set_pmd_at(src_mm, addr, src_pmd, pmd);
992 }
993 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
994 mm_inc_nr_ptes(dst_mm);
995 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
996 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
997 ret = 0;
998 goto out_unlock;
999 }
1000 #endif
1001
1002 if (unlikely(!pmd_trans_huge(pmd))) {
1003 pte_free(dst_mm, pgtable);
1004 goto out_unlock;
1005 }
1006 /*
1007 * When page table lock is held, the huge zero pmd should not be
1008 * under splitting since we don't split the page itself, only pmd to
1009 * a page table.
1010 */
1011 if (is_huge_zero_pmd(pmd)) {
1012 struct page *zero_page;
1013 /*
1014 * get_huge_zero_page() will never allocate a new page here,
1015 * since we already have a zero page to copy. It just takes a
1016 * reference.
1017 */
1018 zero_page = mm_get_huge_zero_page(dst_mm);
1019 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1020 zero_page);
1021 ret = 0;
1022 goto out_unlock;
1023 }
1024
1025 src_page = pmd_page(pmd);
1026 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1027 get_page(src_page);
1028 page_dup_rmap(src_page, true);
1029 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1030 mm_inc_nr_ptes(dst_mm);
1031 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1032
1033 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1034 pmd = pmd_mkold(pmd_wrprotect(pmd));
1035 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1036
1037 ret = 0;
1038 out_unlock:
1039 spin_unlock(src_ptl);
1040 spin_unlock(dst_ptl);
1041 out:
1042 return ret;
1043 }
1044
1045 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1046 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1047 pud_t *pud, int flags)
1048 {
1049 pud_t _pud;
1050
1051 _pud = pud_mkyoung(*pud);
1052 if (flags & FOLL_WRITE)
1053 _pud = pud_mkdirty(_pud);
1054 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1055 pud, _pud, flags & FOLL_WRITE))
1056 update_mmu_cache_pud(vma, addr, pud);
1057 }
1058
1059 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1060 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1061 {
1062 unsigned long pfn = pud_pfn(*pud);
1063 struct mm_struct *mm = vma->vm_mm;
1064 struct page *page;
1065
1066 assert_spin_locked(pud_lockptr(mm, pud));
1067
1068 if (flags & FOLL_WRITE && !pud_write(*pud))
1069 return NULL;
1070
1071 if (pud_present(*pud) && pud_devmap(*pud))
1072 /* pass */;
1073 else
1074 return NULL;
1075
1076 if (flags & FOLL_TOUCH)
1077 touch_pud(vma, addr, pud, flags);
1078
1079 /*
1080 * device mapped pages can only be returned if the
1081 * caller will manage the page reference count.
1082 */
1083 if (!(flags & FOLL_GET))
1084 return ERR_PTR(-EEXIST);
1085
1086 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1087 *pgmap = get_dev_pagemap(pfn, *pgmap);
1088 if (!*pgmap)
1089 return ERR_PTR(-EFAULT);
1090 page = pfn_to_page(pfn);
1091 get_page(page);
1092
1093 return page;
1094 }
1095
1096 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1097 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1098 struct vm_area_struct *vma)
1099 {
1100 spinlock_t *dst_ptl, *src_ptl;
1101 pud_t pud;
1102 int ret;
1103
1104 dst_ptl = pud_lock(dst_mm, dst_pud);
1105 src_ptl = pud_lockptr(src_mm, src_pud);
1106 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1107
1108 ret = -EAGAIN;
1109 pud = *src_pud;
1110 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1111 goto out_unlock;
1112
1113 /*
1114 * When page table lock is held, the huge zero pud should not be
1115 * under splitting since we don't split the page itself, only pud to
1116 * a page table.
1117 */
1118 if (is_huge_zero_pud(pud)) {
1119 /* No huge zero pud yet */
1120 }
1121
1122 pudp_set_wrprotect(src_mm, addr, src_pud);
1123 pud = pud_mkold(pud_wrprotect(pud));
1124 set_pud_at(dst_mm, addr, dst_pud, pud);
1125
1126 ret = 0;
1127 out_unlock:
1128 spin_unlock(src_ptl);
1129 spin_unlock(dst_ptl);
1130 return ret;
1131 }
1132
1133 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1134 {
1135 pud_t entry;
1136 unsigned long haddr;
1137 bool write = vmf->flags & FAULT_FLAG_WRITE;
1138
1139 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1140 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1141 goto unlock;
1142
1143 entry = pud_mkyoung(orig_pud);
1144 if (write)
1145 entry = pud_mkdirty(entry);
1146 haddr = vmf->address & HPAGE_PUD_MASK;
1147 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1148 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1149
1150 unlock:
1151 spin_unlock(vmf->ptl);
1152 }
1153 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1154
1155 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1156 {
1157 pmd_t entry;
1158 unsigned long haddr;
1159 bool write = vmf->flags & FAULT_FLAG_WRITE;
1160
1161 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1162 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1163 goto unlock;
1164
1165 entry = pmd_mkyoung(orig_pmd);
1166 if (write)
1167 entry = pmd_mkdirty(entry);
1168 haddr = vmf->address & HPAGE_PMD_MASK;
1169 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1170 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1171
1172 unlock:
1173 spin_unlock(vmf->ptl);
1174 }
1175
1176 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf,
1177 pmd_t orig_pmd, struct page *page)
1178 {
1179 struct vm_area_struct *vma = vmf->vma;
1180 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1181 struct mem_cgroup *memcg;
1182 pgtable_t pgtable;
1183 pmd_t _pmd;
1184 int i;
1185 vm_fault_t ret = 0;
1186 struct page **pages;
1187 struct mmu_notifier_range range;
1188
1189 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *),
1190 GFP_KERNEL);
1191 if (unlikely(!pages)) {
1192 ret |= VM_FAULT_OOM;
1193 goto out;
1194 }
1195
1196 for (i = 0; i < HPAGE_PMD_NR; i++) {
1197 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1198 vmf->address, page_to_nid(page));
1199 if (unlikely(!pages[i] ||
1200 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm,
1201 GFP_KERNEL, &memcg, false))) {
1202 if (pages[i])
1203 put_page(pages[i]);
1204 while (--i >= 0) {
1205 memcg = (void *)page_private(pages[i]);
1206 set_page_private(pages[i], 0);
1207 mem_cgroup_cancel_charge(pages[i], memcg,
1208 false);
1209 put_page(pages[i]);
1210 }
1211 kfree(pages);
1212 ret |= VM_FAULT_OOM;
1213 goto out;
1214 }
1215 set_page_private(pages[i], (unsigned long)memcg);
1216 }
1217
1218 for (i = 0; i < HPAGE_PMD_NR; i++) {
1219 copy_user_highpage(pages[i], page + i,
1220 haddr + PAGE_SIZE * i, vma);
1221 __SetPageUptodate(pages[i]);
1222 cond_resched();
1223 }
1224
1225 mmu_notifier_range_init(&range, vma->vm_mm, haddr,
1226 haddr + HPAGE_PMD_SIZE);
1227 mmu_notifier_invalidate_range_start(&range);
1228
1229 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1230 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1231 goto out_free_pages;
1232 VM_BUG_ON_PAGE(!PageHead(page), page);
1233
1234 /*
1235 * Leave pmd empty until pte is filled note we must notify here as
1236 * concurrent CPU thread might write to new page before the call to
1237 * mmu_notifier_invalidate_range_end() happens which can lead to a
1238 * device seeing memory write in different order than CPU.
1239 *
1240 * See Documentation/vm/mmu_notifier.rst
1241 */
1242 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1243
1244 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1245 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1246
1247 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1248 pte_t entry;
1249 entry = mk_pte(pages[i], vma->vm_page_prot);
1250 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1251 memcg = (void *)page_private(pages[i]);
1252 set_page_private(pages[i], 0);
1253 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1254 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1255 lru_cache_add_active_or_unevictable(pages[i], vma);
1256 vmf->pte = pte_offset_map(&_pmd, haddr);
1257 VM_BUG_ON(!pte_none(*vmf->pte));
1258 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1259 pte_unmap(vmf->pte);
1260 }
1261 kfree(pages);
1262
1263 smp_wmb(); /* make pte visible before pmd */
1264 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1265 page_remove_rmap(page, true);
1266 spin_unlock(vmf->ptl);
1267
1268 /*
1269 * No need to double call mmu_notifier->invalidate_range() callback as
1270 * the above pmdp_huge_clear_flush_notify() did already call it.
1271 */
1272 mmu_notifier_invalidate_range_only_end(&range);
1273
1274 ret |= VM_FAULT_WRITE;
1275 put_page(page);
1276
1277 out:
1278 return ret;
1279
1280 out_free_pages:
1281 spin_unlock(vmf->ptl);
1282 mmu_notifier_invalidate_range_end(&range);
1283 for (i = 0; i < HPAGE_PMD_NR; i++) {
1284 memcg = (void *)page_private(pages[i]);
1285 set_page_private(pages[i], 0);
1286 mem_cgroup_cancel_charge(pages[i], memcg, false);
1287 put_page(pages[i]);
1288 }
1289 kfree(pages);
1290 goto out;
1291 }
1292
1293 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1294 {
1295 struct vm_area_struct *vma = vmf->vma;
1296 struct page *page = NULL, *new_page;
1297 struct mem_cgroup *memcg;
1298 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1299 struct mmu_notifier_range range;
1300 gfp_t huge_gfp; /* for allocation and charge */
1301 vm_fault_t ret = 0;
1302
1303 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1304 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1305 if (is_huge_zero_pmd(orig_pmd))
1306 goto alloc;
1307 spin_lock(vmf->ptl);
1308 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1309 goto out_unlock;
1310
1311 page = pmd_page(orig_pmd);
1312 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1313 /*
1314 * We can only reuse the page if nobody else maps the huge page or it's
1315 * part.
1316 */
1317 if (!trylock_page(page)) {
1318 get_page(page);
1319 spin_unlock(vmf->ptl);
1320 lock_page(page);
1321 spin_lock(vmf->ptl);
1322 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1323 unlock_page(page);
1324 put_page(page);
1325 goto out_unlock;
1326 }
1327 put_page(page);
1328 }
1329 if (reuse_swap_page(page, NULL)) {
1330 pmd_t entry;
1331 entry = pmd_mkyoung(orig_pmd);
1332 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1333 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1334 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1335 ret |= VM_FAULT_WRITE;
1336 unlock_page(page);
1337 goto out_unlock;
1338 }
1339 unlock_page(page);
1340 get_page(page);
1341 spin_unlock(vmf->ptl);
1342 alloc:
1343 if (__transparent_hugepage_enabled(vma) &&
1344 !transparent_hugepage_debug_cow()) {
1345 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1346 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1347 } else
1348 new_page = NULL;
1349
1350 if (likely(new_page)) {
1351 prep_transhuge_page(new_page);
1352 } else {
1353 if (!page) {
1354 split_huge_pmd(vma, vmf->pmd, vmf->address);
1355 ret |= VM_FAULT_FALLBACK;
1356 } else {
1357 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1358 if (ret & VM_FAULT_OOM) {
1359 split_huge_pmd(vma, vmf->pmd, vmf->address);
1360 ret |= VM_FAULT_FALLBACK;
1361 }
1362 put_page(page);
1363 }
1364 count_vm_event(THP_FAULT_FALLBACK);
1365 goto out;
1366 }
1367
1368 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm,
1369 huge_gfp, &memcg, true))) {
1370 put_page(new_page);
1371 split_huge_pmd(vma, vmf->pmd, vmf->address);
1372 if (page)
1373 put_page(page);
1374 ret |= VM_FAULT_FALLBACK;
1375 count_vm_event(THP_FAULT_FALLBACK);
1376 goto out;
1377 }
1378
1379 count_vm_event(THP_FAULT_ALLOC);
1380
1381 if (!page)
1382 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1383 else
1384 copy_user_huge_page(new_page, page, vmf->address,
1385 vma, HPAGE_PMD_NR);
1386 __SetPageUptodate(new_page);
1387
1388 mmu_notifier_range_init(&range, vma->vm_mm, haddr,
1389 haddr + HPAGE_PMD_SIZE);
1390 mmu_notifier_invalidate_range_start(&range);
1391
1392 spin_lock(vmf->ptl);
1393 if (page)
1394 put_page(page);
1395 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1396 spin_unlock(vmf->ptl);
1397 mem_cgroup_cancel_charge(new_page, memcg, true);
1398 put_page(new_page);
1399 goto out_mn;
1400 } else {
1401 pmd_t entry;
1402 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1403 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1404 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1405 page_add_new_anon_rmap(new_page, vma, haddr, true);
1406 mem_cgroup_commit_charge(new_page, memcg, false, true);
1407 lru_cache_add_active_or_unevictable(new_page, vma);
1408 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1409 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1410 if (!page) {
1411 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1412 } else {
1413 VM_BUG_ON_PAGE(!PageHead(page), page);
1414 page_remove_rmap(page, true);
1415 put_page(page);
1416 }
1417 ret |= VM_FAULT_WRITE;
1418 }
1419 spin_unlock(vmf->ptl);
1420 out_mn:
1421 /*
1422 * No need to double call mmu_notifier->invalidate_range() callback as
1423 * the above pmdp_huge_clear_flush_notify() did already call it.
1424 */
1425 mmu_notifier_invalidate_range_only_end(&range);
1426 out:
1427 return ret;
1428 out_unlock:
1429 spin_unlock(vmf->ptl);
1430 return ret;
1431 }
1432
1433 /*
1434 * FOLL_FORCE can write to even unwritable pmd's, but only
1435 * after we've gone through a COW cycle and they are dirty.
1436 */
1437 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1438 {
1439 return pmd_write(pmd) ||
1440 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1441 }
1442
1443 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1444 unsigned long addr,
1445 pmd_t *pmd,
1446 unsigned int flags)
1447 {
1448 struct mm_struct *mm = vma->vm_mm;
1449 struct page *page = NULL;
1450
1451 assert_spin_locked(pmd_lockptr(mm, pmd));
1452
1453 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1454 goto out;
1455
1456 /* Avoid dumping huge zero page */
1457 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1458 return ERR_PTR(-EFAULT);
1459
1460 /* Full NUMA hinting faults to serialise migration in fault paths */
1461 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1462 goto out;
1463
1464 page = pmd_page(*pmd);
1465 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1466 if (flags & FOLL_TOUCH)
1467 touch_pmd(vma, addr, pmd, flags);
1468 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1469 /*
1470 * We don't mlock() pte-mapped THPs. This way we can avoid
1471 * leaking mlocked pages into non-VM_LOCKED VMAs.
1472 *
1473 * For anon THP:
1474 *
1475 * In most cases the pmd is the only mapping of the page as we
1476 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1477 * writable private mappings in populate_vma_page_range().
1478 *
1479 * The only scenario when we have the page shared here is if we
1480 * mlocking read-only mapping shared over fork(). We skip
1481 * mlocking such pages.
1482 *
1483 * For file THP:
1484 *
1485 * We can expect PageDoubleMap() to be stable under page lock:
1486 * for file pages we set it in page_add_file_rmap(), which
1487 * requires page to be locked.
1488 */
1489
1490 if (PageAnon(page) && compound_mapcount(page) != 1)
1491 goto skip_mlock;
1492 if (PageDoubleMap(page) || !page->mapping)
1493 goto skip_mlock;
1494 if (!trylock_page(page))
1495 goto skip_mlock;
1496 lru_add_drain();
1497 if (page->mapping && !PageDoubleMap(page))
1498 mlock_vma_page(page);
1499 unlock_page(page);
1500 }
1501 skip_mlock:
1502 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1503 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1504 if (flags & FOLL_GET)
1505 get_page(page);
1506
1507 out:
1508 return page;
1509 }
1510
1511 /* NUMA hinting page fault entry point for trans huge pmds */
1512 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1513 {
1514 struct vm_area_struct *vma = vmf->vma;
1515 struct anon_vma *anon_vma = NULL;
1516 struct page *page;
1517 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1518 int page_nid = -1, this_nid = numa_node_id();
1519 int target_nid, last_cpupid = -1;
1520 bool page_locked;
1521 bool migrated = false;
1522 bool was_writable;
1523 int flags = 0;
1524
1525 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1526 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1527 goto out_unlock;
1528
1529 /*
1530 * If there are potential migrations, wait for completion and retry
1531 * without disrupting NUMA hinting information. Do not relock and
1532 * check_same as the page may no longer be mapped.
1533 */
1534 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1535 page = pmd_page(*vmf->pmd);
1536 if (!get_page_unless_zero(page))
1537 goto out_unlock;
1538 spin_unlock(vmf->ptl);
1539 put_and_wait_on_page_locked(page);
1540 goto out;
1541 }
1542
1543 page = pmd_page(pmd);
1544 BUG_ON(is_huge_zero_page(page));
1545 page_nid = page_to_nid(page);
1546 last_cpupid = page_cpupid_last(page);
1547 count_vm_numa_event(NUMA_HINT_FAULTS);
1548 if (page_nid == this_nid) {
1549 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1550 flags |= TNF_FAULT_LOCAL;
1551 }
1552
1553 /* See similar comment in do_numa_page for explanation */
1554 if (!pmd_savedwrite(pmd))
1555 flags |= TNF_NO_GROUP;
1556
1557 /*
1558 * Acquire the page lock to serialise THP migrations but avoid dropping
1559 * page_table_lock if at all possible
1560 */
1561 page_locked = trylock_page(page);
1562 target_nid = mpol_misplaced(page, vma, haddr);
1563 if (target_nid == -1) {
1564 /* If the page was locked, there are no parallel migrations */
1565 if (page_locked)
1566 goto clear_pmdnuma;
1567 }
1568
1569 /* Migration could have started since the pmd_trans_migrating check */
1570 if (!page_locked) {
1571 page_nid = -1;
1572 if (!get_page_unless_zero(page))
1573 goto out_unlock;
1574 spin_unlock(vmf->ptl);
1575 put_and_wait_on_page_locked(page);
1576 goto out;
1577 }
1578
1579 /*
1580 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1581 * to serialises splits
1582 */
1583 get_page(page);
1584 spin_unlock(vmf->ptl);
1585 anon_vma = page_lock_anon_vma_read(page);
1586
1587 /* Confirm the PMD did not change while page_table_lock was released */
1588 spin_lock(vmf->ptl);
1589 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1590 unlock_page(page);
1591 put_page(page);
1592 page_nid = -1;
1593 goto out_unlock;
1594 }
1595
1596 /* Bail if we fail to protect against THP splits for any reason */
1597 if (unlikely(!anon_vma)) {
1598 put_page(page);
1599 page_nid = -1;
1600 goto clear_pmdnuma;
1601 }
1602
1603 /*
1604 * Since we took the NUMA fault, we must have observed the !accessible
1605 * bit. Make sure all other CPUs agree with that, to avoid them
1606 * modifying the page we're about to migrate.
1607 *
1608 * Must be done under PTL such that we'll observe the relevant
1609 * inc_tlb_flush_pending().
1610 *
1611 * We are not sure a pending tlb flush here is for a huge page
1612 * mapping or not. Hence use the tlb range variant
1613 */
1614 if (mm_tlb_flush_pending(vma->vm_mm)) {
1615 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1616 /*
1617 * change_huge_pmd() released the pmd lock before
1618 * invalidating the secondary MMUs sharing the primary
1619 * MMU pagetables (with ->invalidate_range()). The
1620 * mmu_notifier_invalidate_range_end() (which
1621 * internally calls ->invalidate_range()) in
1622 * change_pmd_range() will run after us, so we can't
1623 * rely on it here and we need an explicit invalidate.
1624 */
1625 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1626 haddr + HPAGE_PMD_SIZE);
1627 }
1628
1629 /*
1630 * Migrate the THP to the requested node, returns with page unlocked
1631 * and access rights restored.
1632 */
1633 spin_unlock(vmf->ptl);
1634
1635 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1636 vmf->pmd, pmd, vmf->address, page, target_nid);
1637 if (migrated) {
1638 flags |= TNF_MIGRATED;
1639 page_nid = target_nid;
1640 } else
1641 flags |= TNF_MIGRATE_FAIL;
1642
1643 goto out;
1644 clear_pmdnuma:
1645 BUG_ON(!PageLocked(page));
1646 was_writable = pmd_savedwrite(pmd);
1647 pmd = pmd_modify(pmd, vma->vm_page_prot);
1648 pmd = pmd_mkyoung(pmd);
1649 if (was_writable)
1650 pmd = pmd_mkwrite(pmd);
1651 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1652 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1653 unlock_page(page);
1654 out_unlock:
1655 spin_unlock(vmf->ptl);
1656
1657 out:
1658 if (anon_vma)
1659 page_unlock_anon_vma_read(anon_vma);
1660
1661 if (page_nid != -1)
1662 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1663 flags);
1664
1665 return 0;
1666 }
1667
1668 /*
1669 * Return true if we do MADV_FREE successfully on entire pmd page.
1670 * Otherwise, return false.
1671 */
1672 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1673 pmd_t *pmd, unsigned long addr, unsigned long next)
1674 {
1675 spinlock_t *ptl;
1676 pmd_t orig_pmd;
1677 struct page *page;
1678 struct mm_struct *mm = tlb->mm;
1679 bool ret = false;
1680
1681 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1682
1683 ptl = pmd_trans_huge_lock(pmd, vma);
1684 if (!ptl)
1685 goto out_unlocked;
1686
1687 orig_pmd = *pmd;
1688 if (is_huge_zero_pmd(orig_pmd))
1689 goto out;
1690
1691 if (unlikely(!pmd_present(orig_pmd))) {
1692 VM_BUG_ON(thp_migration_supported() &&
1693 !is_pmd_migration_entry(orig_pmd));
1694 goto out;
1695 }
1696
1697 page = pmd_page(orig_pmd);
1698 /*
1699 * If other processes are mapping this page, we couldn't discard
1700 * the page unless they all do MADV_FREE so let's skip the page.
1701 */
1702 if (page_mapcount(page) != 1)
1703 goto out;
1704
1705 if (!trylock_page(page))
1706 goto out;
1707
1708 /*
1709 * If user want to discard part-pages of THP, split it so MADV_FREE
1710 * will deactivate only them.
1711 */
1712 if (next - addr != HPAGE_PMD_SIZE) {
1713 get_page(page);
1714 spin_unlock(ptl);
1715 split_huge_page(page);
1716 unlock_page(page);
1717 put_page(page);
1718 goto out_unlocked;
1719 }
1720
1721 if (PageDirty(page))
1722 ClearPageDirty(page);
1723 unlock_page(page);
1724
1725 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1726 pmdp_invalidate(vma, addr, pmd);
1727 orig_pmd = pmd_mkold(orig_pmd);
1728 orig_pmd = pmd_mkclean(orig_pmd);
1729
1730 set_pmd_at(mm, addr, pmd, orig_pmd);
1731 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1732 }
1733
1734 mark_page_lazyfree(page);
1735 ret = true;
1736 out:
1737 spin_unlock(ptl);
1738 out_unlocked:
1739 return ret;
1740 }
1741
1742 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1743 {
1744 pgtable_t pgtable;
1745
1746 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1747 pte_free(mm, pgtable);
1748 mm_dec_nr_ptes(mm);
1749 }
1750
1751 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1752 pmd_t *pmd, unsigned long addr)
1753 {
1754 pmd_t orig_pmd;
1755 spinlock_t *ptl;
1756
1757 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1758
1759 ptl = __pmd_trans_huge_lock(pmd, vma);
1760 if (!ptl)
1761 return 0;
1762 /*
1763 * For architectures like ppc64 we look at deposited pgtable
1764 * when calling pmdp_huge_get_and_clear. So do the
1765 * pgtable_trans_huge_withdraw after finishing pmdp related
1766 * operations.
1767 */
1768 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1769 tlb->fullmm);
1770 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1771 if (vma_is_dax(vma)) {
1772 if (arch_needs_pgtable_deposit())
1773 zap_deposited_table(tlb->mm, pmd);
1774 spin_unlock(ptl);
1775 if (is_huge_zero_pmd(orig_pmd))
1776 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1777 } else if (is_huge_zero_pmd(orig_pmd)) {
1778 zap_deposited_table(tlb->mm, pmd);
1779 spin_unlock(ptl);
1780 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1781 } else {
1782 struct page *page = NULL;
1783 int flush_needed = 1;
1784
1785 if (pmd_present(orig_pmd)) {
1786 page = pmd_page(orig_pmd);
1787 page_remove_rmap(page, true);
1788 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1789 VM_BUG_ON_PAGE(!PageHead(page), page);
1790 } else if (thp_migration_supported()) {
1791 swp_entry_t entry;
1792
1793 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1794 entry = pmd_to_swp_entry(orig_pmd);
1795 page = pfn_to_page(swp_offset(entry));
1796 flush_needed = 0;
1797 } else
1798 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1799
1800 if (PageAnon(page)) {
1801 zap_deposited_table(tlb->mm, pmd);
1802 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1803 } else {
1804 if (arch_needs_pgtable_deposit())
1805 zap_deposited_table(tlb->mm, pmd);
1806 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1807 }
1808
1809 spin_unlock(ptl);
1810 if (flush_needed)
1811 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1812 }
1813 return 1;
1814 }
1815
1816 #ifndef pmd_move_must_withdraw
1817 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1818 spinlock_t *old_pmd_ptl,
1819 struct vm_area_struct *vma)
1820 {
1821 /*
1822 * With split pmd lock we also need to move preallocated
1823 * PTE page table if new_pmd is on different PMD page table.
1824 *
1825 * We also don't deposit and withdraw tables for file pages.
1826 */
1827 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1828 }
1829 #endif
1830
1831 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1832 {
1833 #ifdef CONFIG_MEM_SOFT_DIRTY
1834 if (unlikely(is_pmd_migration_entry(pmd)))
1835 pmd = pmd_swp_mksoft_dirty(pmd);
1836 else if (pmd_present(pmd))
1837 pmd = pmd_mksoft_dirty(pmd);
1838 #endif
1839 return pmd;
1840 }
1841
1842 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1843 unsigned long new_addr, unsigned long old_end,
1844 pmd_t *old_pmd, pmd_t *new_pmd)
1845 {
1846 spinlock_t *old_ptl, *new_ptl;
1847 pmd_t pmd;
1848 struct mm_struct *mm = vma->vm_mm;
1849 bool force_flush = false;
1850
1851 if ((old_addr & ~HPAGE_PMD_MASK) ||
1852 (new_addr & ~HPAGE_PMD_MASK) ||
1853 old_end - old_addr < HPAGE_PMD_SIZE)
1854 return false;
1855
1856 /*
1857 * The destination pmd shouldn't be established, free_pgtables()
1858 * should have release it.
1859 */
1860 if (WARN_ON(!pmd_none(*new_pmd))) {
1861 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1862 return false;
1863 }
1864
1865 /*
1866 * We don't have to worry about the ordering of src and dst
1867 * ptlocks because exclusive mmap_sem prevents deadlock.
1868 */
1869 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1870 if (old_ptl) {
1871 new_ptl = pmd_lockptr(mm, new_pmd);
1872 if (new_ptl != old_ptl)
1873 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1874 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1875 if (pmd_present(pmd))
1876 force_flush = true;
1877 VM_BUG_ON(!pmd_none(*new_pmd));
1878
1879 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1880 pgtable_t pgtable;
1881 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1882 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1883 }
1884 pmd = move_soft_dirty_pmd(pmd);
1885 set_pmd_at(mm, new_addr, new_pmd, pmd);
1886 if (force_flush)
1887 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1888 if (new_ptl != old_ptl)
1889 spin_unlock(new_ptl);
1890 spin_unlock(old_ptl);
1891 return true;
1892 }
1893 return false;
1894 }
1895
1896 /*
1897 * Returns
1898 * - 0 if PMD could not be locked
1899 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1900 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1901 */
1902 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1903 unsigned long addr, pgprot_t newprot, int prot_numa)
1904 {
1905 struct mm_struct *mm = vma->vm_mm;
1906 spinlock_t *ptl;
1907 pmd_t entry;
1908 bool preserve_write;
1909 int ret;
1910
1911 ptl = __pmd_trans_huge_lock(pmd, vma);
1912 if (!ptl)
1913 return 0;
1914
1915 preserve_write = prot_numa && pmd_write(*pmd);
1916 ret = 1;
1917
1918 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1919 if (is_swap_pmd(*pmd)) {
1920 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1921
1922 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1923 if (is_write_migration_entry(entry)) {
1924 pmd_t newpmd;
1925 /*
1926 * A protection check is difficult so
1927 * just be safe and disable write
1928 */
1929 make_migration_entry_read(&entry);
1930 newpmd = swp_entry_to_pmd(entry);
1931 if (pmd_swp_soft_dirty(*pmd))
1932 newpmd = pmd_swp_mksoft_dirty(newpmd);
1933 set_pmd_at(mm, addr, pmd, newpmd);
1934 }
1935 goto unlock;
1936 }
1937 #endif
1938
1939 /*
1940 * Avoid trapping faults against the zero page. The read-only
1941 * data is likely to be read-cached on the local CPU and
1942 * local/remote hits to the zero page are not interesting.
1943 */
1944 if (prot_numa && is_huge_zero_pmd(*pmd))
1945 goto unlock;
1946
1947 if (prot_numa && pmd_protnone(*pmd))
1948 goto unlock;
1949
1950 /*
1951 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1952 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1953 * which is also under down_read(mmap_sem):
1954 *
1955 * CPU0: CPU1:
1956 * change_huge_pmd(prot_numa=1)
1957 * pmdp_huge_get_and_clear_notify()
1958 * madvise_dontneed()
1959 * zap_pmd_range()
1960 * pmd_trans_huge(*pmd) == 0 (without ptl)
1961 * // skip the pmd
1962 * set_pmd_at();
1963 * // pmd is re-established
1964 *
1965 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1966 * which may break userspace.
1967 *
1968 * pmdp_invalidate() is required to make sure we don't miss
1969 * dirty/young flags set by hardware.
1970 */
1971 entry = pmdp_invalidate(vma, addr, pmd);
1972
1973 entry = pmd_modify(entry, newprot);
1974 if (preserve_write)
1975 entry = pmd_mk_savedwrite(entry);
1976 ret = HPAGE_PMD_NR;
1977 set_pmd_at(mm, addr, pmd, entry);
1978 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1979 unlock:
1980 spin_unlock(ptl);
1981 return ret;
1982 }
1983
1984 /*
1985 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1986 *
1987 * Note that if it returns page table lock pointer, this routine returns without
1988 * unlocking page table lock. So callers must unlock it.
1989 */
1990 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1991 {
1992 spinlock_t *ptl;
1993 ptl = pmd_lock(vma->vm_mm, pmd);
1994 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1995 pmd_devmap(*pmd)))
1996 return ptl;
1997 spin_unlock(ptl);
1998 return NULL;
1999 }
2000
2001 /*
2002 * Returns true if a given pud maps a thp, false otherwise.
2003 *
2004 * Note that if it returns true, this routine returns without unlocking page
2005 * table lock. So callers must unlock it.
2006 */
2007 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
2008 {
2009 spinlock_t *ptl;
2010
2011 ptl = pud_lock(vma->vm_mm, pud);
2012 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
2013 return ptl;
2014 spin_unlock(ptl);
2015 return NULL;
2016 }
2017
2018 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2019 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
2020 pud_t *pud, unsigned long addr)
2021 {
2022 pud_t orig_pud;
2023 spinlock_t *ptl;
2024
2025 ptl = __pud_trans_huge_lock(pud, vma);
2026 if (!ptl)
2027 return 0;
2028 /*
2029 * For architectures like ppc64 we look at deposited pgtable
2030 * when calling pudp_huge_get_and_clear. So do the
2031 * pgtable_trans_huge_withdraw after finishing pudp related
2032 * operations.
2033 */
2034 orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
2035 tlb->fullmm);
2036 tlb_remove_pud_tlb_entry(tlb, pud, addr);
2037 if (vma_is_dax(vma)) {
2038 spin_unlock(ptl);
2039 /* No zero page support yet */
2040 } else {
2041 /* No support for anonymous PUD pages yet */
2042 BUG();
2043 }
2044 return 1;
2045 }
2046
2047 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2048 unsigned long haddr)
2049 {
2050 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2051 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2052 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2053 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2054
2055 count_vm_event(THP_SPLIT_PUD);
2056
2057 pudp_huge_clear_flush_notify(vma, haddr, pud);
2058 }
2059
2060 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2061 unsigned long address)
2062 {
2063 spinlock_t *ptl;
2064 struct mmu_notifier_range range;
2065
2066 mmu_notifier_range_init(&range, vma->vm_mm, address & HPAGE_PUD_MASK,
2067 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2068 mmu_notifier_invalidate_range_start(&range);
2069 ptl = pud_lock(vma->vm_mm, pud);
2070 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2071 goto out;
2072 __split_huge_pud_locked(vma, pud, range.start);
2073
2074 out:
2075 spin_unlock(ptl);
2076 /*
2077 * No need to double call mmu_notifier->invalidate_range() callback as
2078 * the above pudp_huge_clear_flush_notify() did already call it.
2079 */
2080 mmu_notifier_invalidate_range_only_end(&range);
2081 }
2082 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2083
2084 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2085 unsigned long haddr, pmd_t *pmd)
2086 {
2087 struct mm_struct *mm = vma->vm_mm;
2088 pgtable_t pgtable;
2089 pmd_t _pmd;
2090 int i;
2091
2092 /*
2093 * Leave pmd empty until pte is filled note that it is fine to delay
2094 * notification until mmu_notifier_invalidate_range_end() as we are
2095 * replacing a zero pmd write protected page with a zero pte write
2096 * protected page.
2097 *
2098 * See Documentation/vm/mmu_notifier.rst
2099 */
2100 pmdp_huge_clear_flush(vma, haddr, pmd);
2101
2102 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2103 pmd_populate(mm, &_pmd, pgtable);
2104
2105 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2106 pte_t *pte, entry;
2107 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2108 entry = pte_mkspecial(entry);
2109 pte = pte_offset_map(&_pmd, haddr);
2110 VM_BUG_ON(!pte_none(*pte));
2111 set_pte_at(mm, haddr, pte, entry);
2112 pte_unmap(pte);
2113 }
2114 smp_wmb(); /* make pte visible before pmd */
2115 pmd_populate(mm, pmd, pgtable);
2116 }
2117
2118 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2119 unsigned long haddr, bool freeze)
2120 {
2121 struct mm_struct *mm = vma->vm_mm;
2122 struct page *page;
2123 pgtable_t pgtable;
2124 pmd_t old_pmd, _pmd;
2125 bool young, write, soft_dirty, pmd_migration = false;
2126 unsigned long addr;
2127 int i;
2128
2129 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2130 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2131 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2132 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2133 && !pmd_devmap(*pmd));
2134
2135 count_vm_event(THP_SPLIT_PMD);
2136
2137 if (!vma_is_anonymous(vma)) {
2138 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2139 /*
2140 * We are going to unmap this huge page. So
2141 * just go ahead and zap it
2142 */
2143 if (arch_needs_pgtable_deposit())
2144 zap_deposited_table(mm, pmd);
2145 if (vma_is_dax(vma))
2146 return;
2147 page = pmd_page(_pmd);
2148 if (!PageDirty(page) && pmd_dirty(_pmd))
2149 set_page_dirty(page);
2150 if (!PageReferenced(page) && pmd_young(_pmd))
2151 SetPageReferenced(page);
2152 page_remove_rmap(page, true);
2153 put_page(page);
2154 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2155 return;
2156 } else if (is_huge_zero_pmd(*pmd)) {
2157 /*
2158 * FIXME: Do we want to invalidate secondary mmu by calling
2159 * mmu_notifier_invalidate_range() see comments below inside
2160 * __split_huge_pmd() ?
2161 *
2162 * We are going from a zero huge page write protected to zero
2163 * small page also write protected so it does not seems useful
2164 * to invalidate secondary mmu at this time.
2165 */
2166 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2167 }
2168
2169 /*
2170 * Up to this point the pmd is present and huge and userland has the
2171 * whole access to the hugepage during the split (which happens in
2172 * place). If we overwrite the pmd with the not-huge version pointing
2173 * to the pte here (which of course we could if all CPUs were bug
2174 * free), userland could trigger a small page size TLB miss on the
2175 * small sized TLB while the hugepage TLB entry is still established in
2176 * the huge TLB. Some CPU doesn't like that.
2177 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2178 * 383 on page 93. Intel should be safe but is also warns that it's
2179 * only safe if the permission and cache attributes of the two entries
2180 * loaded in the two TLB is identical (which should be the case here).
2181 * But it is generally safer to never allow small and huge TLB entries
2182 * for the same virtual address to be loaded simultaneously. So instead
2183 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2184 * current pmd notpresent (atomically because here the pmd_trans_huge
2185 * must remain set at all times on the pmd until the split is complete
2186 * for this pmd), then we flush the SMP TLB and finally we write the
2187 * non-huge version of the pmd entry with pmd_populate.
2188 */
2189 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2190
2191 pmd_migration = is_pmd_migration_entry(old_pmd);
2192 if (unlikely(pmd_migration)) {
2193 swp_entry_t entry;
2194
2195 entry = pmd_to_swp_entry(old_pmd);
2196 page = pfn_to_page(swp_offset(entry));
2197 write = is_write_migration_entry(entry);
2198 young = false;
2199 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2200 } else {
2201 page = pmd_page(old_pmd);
2202 if (pmd_dirty(old_pmd))
2203 SetPageDirty(page);
2204 write = pmd_write(old_pmd);
2205 young = pmd_young(old_pmd);
2206 soft_dirty = pmd_soft_dirty(old_pmd);
2207 }
2208 VM_BUG_ON_PAGE(!page_count(page), page);
2209 page_ref_add(page, HPAGE_PMD_NR - 1);
2210
2211 /*
2212 * Withdraw the table only after we mark the pmd entry invalid.
2213 * This's critical for some architectures (Power).
2214 */
2215 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2216 pmd_populate(mm, &_pmd, pgtable);
2217
2218 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2219 pte_t entry, *pte;
2220 /*
2221 * Note that NUMA hinting access restrictions are not
2222 * transferred to avoid any possibility of altering
2223 * permissions across VMAs.
2224 */
2225 if (freeze || pmd_migration) {
2226 swp_entry_t swp_entry;
2227 swp_entry = make_migration_entry(page + i, write);
2228 entry = swp_entry_to_pte(swp_entry);
2229 if (soft_dirty)
2230 entry = pte_swp_mksoft_dirty(entry);
2231 } else {
2232 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2233 entry = maybe_mkwrite(entry, vma);
2234 if (!write)
2235 entry = pte_wrprotect(entry);
2236 if (!young)
2237 entry = pte_mkold(entry);
2238 if (soft_dirty)
2239 entry = pte_mksoft_dirty(entry);
2240 }
2241 pte = pte_offset_map(&_pmd, addr);
2242 BUG_ON(!pte_none(*pte));
2243 set_pte_at(mm, addr, pte, entry);
2244 atomic_inc(&page[i]._mapcount);
2245 pte_unmap(pte);
2246 }
2247
2248 /*
2249 * Set PG_double_map before dropping compound_mapcount to avoid
2250 * false-negative page_mapped().
2251 */
2252 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2253 for (i = 0; i < HPAGE_PMD_NR; i++)
2254 atomic_inc(&page[i]._mapcount);
2255 }
2256
2257 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2258 /* Last compound_mapcount is gone. */
2259 __dec_node_page_state(page, NR_ANON_THPS);
2260 if (TestClearPageDoubleMap(page)) {
2261 /* No need in mapcount reference anymore */
2262 for (i = 0; i < HPAGE_PMD_NR; i++)
2263 atomic_dec(&page[i]._mapcount);
2264 }
2265 }
2266
2267 smp_wmb(); /* make pte visible before pmd */
2268 pmd_populate(mm, pmd, pgtable);
2269
2270 if (freeze) {
2271 for (i = 0; i < HPAGE_PMD_NR; i++) {
2272 page_remove_rmap(page + i, false);
2273 put_page(page + i);
2274 }
2275 }
2276 }
2277
2278 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2279 unsigned long address, bool freeze, struct page *page)
2280 {
2281 spinlock_t *ptl;
2282 struct mmu_notifier_range range;
2283
2284 mmu_notifier_range_init(&range, vma->vm_mm, address & HPAGE_PMD_MASK,
2285 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2286 mmu_notifier_invalidate_range_start(&range);
2287 ptl = pmd_lock(vma->vm_mm, pmd);
2288
2289 /*
2290 * If caller asks to setup a migration entries, we need a page to check
2291 * pmd against. Otherwise we can end up replacing wrong page.
2292 */
2293 VM_BUG_ON(freeze && !page);
2294 if (page && page != pmd_page(*pmd))
2295 goto out;
2296
2297 if (pmd_trans_huge(*pmd)) {
2298 page = pmd_page(*pmd);
2299 if (PageMlocked(page))
2300 clear_page_mlock(page);
2301 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2302 goto out;
2303 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2304 out:
2305 spin_unlock(ptl);
2306 /*
2307 * No need to double call mmu_notifier->invalidate_range() callback.
2308 * They are 3 cases to consider inside __split_huge_pmd_locked():
2309 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2310 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2311 * fault will trigger a flush_notify before pointing to a new page
2312 * (it is fine if the secondary mmu keeps pointing to the old zero
2313 * page in the meantime)
2314 * 3) Split a huge pmd into pte pointing to the same page. No need
2315 * to invalidate secondary tlb entry they are all still valid.
2316 * any further changes to individual pte will notify. So no need
2317 * to call mmu_notifier->invalidate_range()
2318 */
2319 mmu_notifier_invalidate_range_only_end(&range);
2320 }
2321
2322 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2323 bool freeze, struct page *page)
2324 {
2325 pgd_t *pgd;
2326 p4d_t *p4d;
2327 pud_t *pud;
2328 pmd_t *pmd;
2329
2330 pgd = pgd_offset(vma->vm_mm, address);
2331 if (!pgd_present(*pgd))
2332 return;
2333
2334 p4d = p4d_offset(pgd, address);
2335 if (!p4d_present(*p4d))
2336 return;
2337
2338 pud = pud_offset(p4d, address);
2339 if (!pud_present(*pud))
2340 return;
2341
2342 pmd = pmd_offset(pud, address);
2343
2344 __split_huge_pmd(vma, pmd, address, freeze, page);
2345 }
2346
2347 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2348 unsigned long start,
2349 unsigned long end,
2350 long adjust_next)
2351 {
2352 /*
2353 * If the new start address isn't hpage aligned and it could
2354 * previously contain an hugepage: check if we need to split
2355 * an huge pmd.
2356 */
2357 if (start & ~HPAGE_PMD_MASK &&
2358 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2359 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2360 split_huge_pmd_address(vma, start, false, NULL);
2361
2362 /*
2363 * If the new end address isn't hpage aligned and it could
2364 * previously contain an hugepage: check if we need to split
2365 * an huge pmd.
2366 */
2367 if (end & ~HPAGE_PMD_MASK &&
2368 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2369 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2370 split_huge_pmd_address(vma, end, false, NULL);
2371
2372 /*
2373 * If we're also updating the vma->vm_next->vm_start, if the new
2374 * vm_next->vm_start isn't page aligned and it could previously
2375 * contain an hugepage: check if we need to split an huge pmd.
2376 */
2377 if (adjust_next > 0) {
2378 struct vm_area_struct *next = vma->vm_next;
2379 unsigned long nstart = next->vm_start;
2380 nstart += adjust_next << PAGE_SHIFT;
2381 if (nstart & ~HPAGE_PMD_MASK &&
2382 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2383 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2384 split_huge_pmd_address(next, nstart, false, NULL);
2385 }
2386 }
2387
2388 static void unmap_page(struct page *page)
2389 {
2390 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2391 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2392 bool unmap_success;
2393
2394 VM_BUG_ON_PAGE(!PageHead(page), page);
2395
2396 if (PageAnon(page))
2397 ttu_flags |= TTU_SPLIT_FREEZE;
2398
2399 unmap_success = try_to_unmap(page, ttu_flags);
2400 VM_BUG_ON_PAGE(!unmap_success, page);
2401 }
2402
2403 static void remap_page(struct page *page)
2404 {
2405 int i;
2406 if (PageTransHuge(page)) {
2407 remove_migration_ptes(page, page, true);
2408 } else {
2409 for (i = 0; i < HPAGE_PMD_NR; i++)
2410 remove_migration_ptes(page + i, page + i, true);
2411 }
2412 }
2413
2414 static void __split_huge_page_tail(struct page *head, int tail,
2415 struct lruvec *lruvec, struct list_head *list)
2416 {
2417 struct page *page_tail = head + tail;
2418
2419 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2420
2421 /*
2422 * Clone page flags before unfreezing refcount.
2423 *
2424 * After successful get_page_unless_zero() might follow flags change,
2425 * for exmaple lock_page() which set PG_waiters.
2426 */
2427 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2428 page_tail->flags |= (head->flags &
2429 ((1L << PG_referenced) |
2430 (1L << PG_swapbacked) |
2431 (1L << PG_swapcache) |
2432 (1L << PG_mlocked) |
2433 (1L << PG_uptodate) |
2434 (1L << PG_active) |
2435 (1L << PG_workingset) |
2436 (1L << PG_locked) |
2437 (1L << PG_unevictable) |
2438 (1L << PG_dirty)));
2439
2440 /* ->mapping in first tail page is compound_mapcount */
2441 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2442 page_tail);
2443 page_tail->mapping = head->mapping;
2444 page_tail->index = head->index + tail;
2445
2446 /* Page flags must be visible before we make the page non-compound. */
2447 smp_wmb();
2448
2449 /*
2450 * Clear PageTail before unfreezing page refcount.
2451 *
2452 * After successful get_page_unless_zero() might follow put_page()
2453 * which needs correct compound_head().
2454 */
2455 clear_compound_head(page_tail);
2456
2457 /* Finally unfreeze refcount. Additional reference from page cache. */
2458 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2459 PageSwapCache(head)));
2460
2461 if (page_is_young(head))
2462 set_page_young(page_tail);
2463 if (page_is_idle(head))
2464 set_page_idle(page_tail);
2465
2466 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2467
2468 /*
2469 * always add to the tail because some iterators expect new
2470 * pages to show after the currently processed elements - e.g.
2471 * migrate_pages
2472 */
2473 lru_add_page_tail(head, page_tail, lruvec, list);
2474 }
2475
2476 static void __split_huge_page(struct page *page, struct list_head *list,
2477 pgoff_t end, unsigned long flags)
2478 {
2479 struct page *head = compound_head(page);
2480 struct zone *zone = page_zone(head);
2481 struct lruvec *lruvec;
2482 int i;
2483
2484 lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2485
2486 /* complete memcg works before add pages to LRU */
2487 mem_cgroup_split_huge_fixup(head);
2488
2489 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2490 __split_huge_page_tail(head, i, lruvec, list);
2491 /* Some pages can be beyond i_size: drop them from page cache */
2492 if (head[i].index >= end) {
2493 ClearPageDirty(head + i);
2494 __delete_from_page_cache(head + i, NULL);
2495 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2496 shmem_uncharge(head->mapping->host, 1);
2497 put_page(head + i);
2498 }
2499 }
2500
2501 ClearPageCompound(head);
2502 /* See comment in __split_huge_page_tail() */
2503 if (PageAnon(head)) {
2504 /* Additional pin to swap cache */
2505 if (PageSwapCache(head))
2506 page_ref_add(head, 2);
2507 else
2508 page_ref_inc(head);
2509 } else {
2510 /* Additional pin to page cache */
2511 page_ref_add(head, 2);
2512 xa_unlock(&head->mapping->i_pages);
2513 }
2514
2515 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2516
2517 remap_page(head);
2518
2519 for (i = 0; i < HPAGE_PMD_NR; i++) {
2520 struct page *subpage = head + i;
2521 if (subpage == page)
2522 continue;
2523 unlock_page(subpage);
2524
2525 /*
2526 * Subpages may be freed if there wasn't any mapping
2527 * like if add_to_swap() is running on a lru page that
2528 * had its mapping zapped. And freeing these pages
2529 * requires taking the lru_lock so we do the put_page
2530 * of the tail pages after the split is complete.
2531 */
2532 put_page(subpage);
2533 }
2534 }
2535
2536 int total_mapcount(struct page *page)
2537 {
2538 int i, compound, ret;
2539
2540 VM_BUG_ON_PAGE(PageTail(page), page);
2541
2542 if (likely(!PageCompound(page)))
2543 return atomic_read(&page->_mapcount) + 1;
2544
2545 compound = compound_mapcount(page);
2546 if (PageHuge(page))
2547 return compound;
2548 ret = compound;
2549 for (i = 0; i < HPAGE_PMD_NR; i++)
2550 ret += atomic_read(&page[i]._mapcount) + 1;
2551 /* File pages has compound_mapcount included in _mapcount */
2552 if (!PageAnon(page))
2553 return ret - compound * HPAGE_PMD_NR;
2554 if (PageDoubleMap(page))
2555 ret -= HPAGE_PMD_NR;
2556 return ret;
2557 }
2558
2559 /*
2560 * This calculates accurately how many mappings a transparent hugepage
2561 * has (unlike page_mapcount() which isn't fully accurate). This full
2562 * accuracy is primarily needed to know if copy-on-write faults can
2563 * reuse the page and change the mapping to read-write instead of
2564 * copying them. At the same time this returns the total_mapcount too.
2565 *
2566 * The function returns the highest mapcount any one of the subpages
2567 * has. If the return value is one, even if different processes are
2568 * mapping different subpages of the transparent hugepage, they can
2569 * all reuse it, because each process is reusing a different subpage.
2570 *
2571 * The total_mapcount is instead counting all virtual mappings of the
2572 * subpages. If the total_mapcount is equal to "one", it tells the
2573 * caller all mappings belong to the same "mm" and in turn the
2574 * anon_vma of the transparent hugepage can become the vma->anon_vma
2575 * local one as no other process may be mapping any of the subpages.
2576 *
2577 * It would be more accurate to replace page_mapcount() with
2578 * page_trans_huge_mapcount(), however we only use
2579 * page_trans_huge_mapcount() in the copy-on-write faults where we
2580 * need full accuracy to avoid breaking page pinning, because
2581 * page_trans_huge_mapcount() is slower than page_mapcount().
2582 */
2583 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2584 {
2585 int i, ret, _total_mapcount, mapcount;
2586
2587 /* hugetlbfs shouldn't call it */
2588 VM_BUG_ON_PAGE(PageHuge(page), page);
2589
2590 if (likely(!PageTransCompound(page))) {
2591 mapcount = atomic_read(&page->_mapcount) + 1;
2592 if (total_mapcount)
2593 *total_mapcount = mapcount;
2594 return mapcount;
2595 }
2596
2597 page = compound_head(page);
2598
2599 _total_mapcount = ret = 0;
2600 for (i = 0; i < HPAGE_PMD_NR; i++) {
2601 mapcount = atomic_read(&page[i]._mapcount) + 1;
2602 ret = max(ret, mapcount);
2603 _total_mapcount += mapcount;
2604 }
2605 if (PageDoubleMap(page)) {
2606 ret -= 1;
2607 _total_mapcount -= HPAGE_PMD_NR;
2608 }
2609 mapcount = compound_mapcount(page);
2610 ret += mapcount;
2611 _total_mapcount += mapcount;
2612 if (total_mapcount)
2613 *total_mapcount = _total_mapcount;
2614 return ret;
2615 }
2616
2617 /* Racy check whether the huge page can be split */
2618 bool can_split_huge_page(struct page *page, int *pextra_pins)
2619 {
2620 int extra_pins;
2621
2622 /* Additional pins from page cache */
2623 if (PageAnon(page))
2624 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2625 else
2626 extra_pins = HPAGE_PMD_NR;
2627 if (pextra_pins)
2628 *pextra_pins = extra_pins;
2629 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2630 }
2631
2632 /*
2633 * This function splits huge page into normal pages. @page can point to any
2634 * subpage of huge page to split. Split doesn't change the position of @page.
2635 *
2636 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2637 * The huge page must be locked.
2638 *
2639 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2640 *
2641 * Both head page and tail pages will inherit mapping, flags, and so on from
2642 * the hugepage.
2643 *
2644 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2645 * they are not mapped.
2646 *
2647 * Returns 0 if the hugepage is split successfully.
2648 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2649 * us.
2650 */
2651 int split_huge_page_to_list(struct page *page, struct list_head *list)
2652 {
2653 struct page *head = compound_head(page);
2654 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2655 struct anon_vma *anon_vma = NULL;
2656 struct address_space *mapping = NULL;
2657 int count, mapcount, extra_pins, ret;
2658 bool mlocked;
2659 unsigned long flags;
2660 pgoff_t end;
2661
2662 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2663 VM_BUG_ON_PAGE(!PageLocked(page), page);
2664 VM_BUG_ON_PAGE(!PageCompound(page), page);
2665
2666 if (PageWriteback(page))
2667 return -EBUSY;
2668
2669 if (PageAnon(head)) {
2670 /*
2671 * The caller does not necessarily hold an mmap_sem that would
2672 * prevent the anon_vma disappearing so we first we take a
2673 * reference to it and then lock the anon_vma for write. This
2674 * is similar to page_lock_anon_vma_read except the write lock
2675 * is taken to serialise against parallel split or collapse
2676 * operations.
2677 */
2678 anon_vma = page_get_anon_vma(head);
2679 if (!anon_vma) {
2680 ret = -EBUSY;
2681 goto out;
2682 }
2683 end = -1;
2684 mapping = NULL;
2685 anon_vma_lock_write(anon_vma);
2686 } else {
2687 mapping = head->mapping;
2688
2689 /* Truncated ? */
2690 if (!mapping) {
2691 ret = -EBUSY;
2692 goto out;
2693 }
2694
2695 anon_vma = NULL;
2696 i_mmap_lock_read(mapping);
2697
2698 /*
2699 *__split_huge_page() may need to trim off pages beyond EOF:
2700 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2701 * which cannot be nested inside the page tree lock. So note
2702 * end now: i_size itself may be changed at any moment, but
2703 * head page lock is good enough to serialize the trimming.
2704 */
2705 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2706 }
2707
2708 /*
2709 * Racy check if we can split the page, before unmap_page() will
2710 * split PMDs
2711 */
2712 if (!can_split_huge_page(head, &extra_pins)) {
2713 ret = -EBUSY;
2714 goto out_unlock;
2715 }
2716
2717 mlocked = PageMlocked(page);
2718 unmap_page(head);
2719 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2720
2721 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2722 if (mlocked)
2723 lru_add_drain();
2724
2725 /* prevent PageLRU to go away from under us, and freeze lru stats */
2726 spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2727
2728 if (mapping) {
2729 XA_STATE(xas, &mapping->i_pages, page_index(head));
2730
2731 /*
2732 * Check if the head page is present in page cache.
2733 * We assume all tail are present too, if head is there.
2734 */
2735 xa_lock(&mapping->i_pages);
2736 if (xas_load(&xas) != head)
2737 goto fail;
2738 }
2739
2740 /* Prevent deferred_split_scan() touching ->_refcount */
2741 spin_lock(&pgdata->split_queue_lock);
2742 count = page_count(head);
2743 mapcount = total_mapcount(head);
2744 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2745 if (!list_empty(page_deferred_list(head))) {
2746 pgdata->split_queue_len--;
2747 list_del(page_deferred_list(head));
2748 }
2749 if (mapping)
2750 __dec_node_page_state(page, NR_SHMEM_THPS);
2751 spin_unlock(&pgdata->split_queue_lock);
2752 __split_huge_page(page, list, end, flags);
2753 if (PageSwapCache(head)) {
2754 swp_entry_t entry = { .val = page_private(head) };
2755
2756 ret = split_swap_cluster(entry);
2757 } else
2758 ret = 0;
2759 } else {
2760 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2761 pr_alert("total_mapcount: %u, page_count(): %u\n",
2762 mapcount, count);
2763 if (PageTail(page))
2764 dump_page(head, NULL);
2765 dump_page(page, "total_mapcount(head) > 0");
2766 BUG();
2767 }
2768 spin_unlock(&pgdata->split_queue_lock);
2769 fail: if (mapping)
2770 xa_unlock(&mapping->i_pages);
2771 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2772 remap_page(head);
2773 ret = -EBUSY;
2774 }
2775
2776 out_unlock:
2777 if (anon_vma) {
2778 anon_vma_unlock_write(anon_vma);
2779 put_anon_vma(anon_vma);
2780 }
2781 if (mapping)
2782 i_mmap_unlock_read(mapping);
2783 out:
2784 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2785 return ret;
2786 }
2787
2788 void free_transhuge_page(struct page *page)
2789 {
2790 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2791 unsigned long flags;
2792
2793 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2794 if (!list_empty(page_deferred_list(page))) {
2795 pgdata->split_queue_len--;
2796 list_del(page_deferred_list(page));
2797 }
2798 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2799 free_compound_page(page);
2800 }
2801
2802 void deferred_split_huge_page(struct page *page)
2803 {
2804 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2805 unsigned long flags;
2806
2807 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2808
2809 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2810 if (list_empty(page_deferred_list(page))) {
2811 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2812 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2813 pgdata->split_queue_len++;
2814 }
2815 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2816 }
2817
2818 static unsigned long deferred_split_count(struct shrinker *shrink,
2819 struct shrink_control *sc)
2820 {
2821 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2822 return READ_ONCE(pgdata->split_queue_len);
2823 }
2824
2825 static unsigned long deferred_split_scan(struct shrinker *shrink,
2826 struct shrink_control *sc)
2827 {
2828 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2829 unsigned long flags;
2830 LIST_HEAD(list), *pos, *next;
2831 struct page *page;
2832 int split = 0;
2833
2834 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2835 /* Take pin on all head pages to avoid freeing them under us */
2836 list_for_each_safe(pos, next, &pgdata->split_queue) {
2837 page = list_entry((void *)pos, struct page, mapping);
2838 page = compound_head(page);
2839 if (get_page_unless_zero(page)) {
2840 list_move(page_deferred_list(page), &list);
2841 } else {
2842 /* We lost race with put_compound_page() */
2843 list_del_init(page_deferred_list(page));
2844 pgdata->split_queue_len--;
2845 }
2846 if (!--sc->nr_to_scan)
2847 break;
2848 }
2849 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2850
2851 list_for_each_safe(pos, next, &list) {
2852 page = list_entry((void *)pos, struct page, mapping);
2853 if (!trylock_page(page))
2854 goto next;
2855 /* split_huge_page() removes page from list on success */
2856 if (!split_huge_page(page))
2857 split++;
2858 unlock_page(page);
2859 next:
2860 put_page(page);
2861 }
2862
2863 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2864 list_splice_tail(&list, &pgdata->split_queue);
2865 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2866
2867 /*
2868 * Stop shrinker if we didn't split any page, but the queue is empty.
2869 * This can happen if pages were freed under us.
2870 */
2871 if (!split && list_empty(&pgdata->split_queue))
2872 return SHRINK_STOP;
2873 return split;
2874 }
2875
2876 static struct shrinker deferred_split_shrinker = {
2877 .count_objects = deferred_split_count,
2878 .scan_objects = deferred_split_scan,
2879 .seeks = DEFAULT_SEEKS,
2880 .flags = SHRINKER_NUMA_AWARE,
2881 };
2882
2883 #ifdef CONFIG_DEBUG_FS
2884 static int split_huge_pages_set(void *data, u64 val)
2885 {
2886 struct zone *zone;
2887 struct page *page;
2888 unsigned long pfn, max_zone_pfn;
2889 unsigned long total = 0, split = 0;
2890
2891 if (val != 1)
2892 return -EINVAL;
2893
2894 for_each_populated_zone(zone) {
2895 max_zone_pfn = zone_end_pfn(zone);
2896 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2897 if (!pfn_valid(pfn))
2898 continue;
2899
2900 page = pfn_to_page(pfn);
2901 if (!get_page_unless_zero(page))
2902 continue;
2903
2904 if (zone != page_zone(page))
2905 goto next;
2906
2907 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2908 goto next;
2909
2910 total++;
2911 lock_page(page);
2912 if (!split_huge_page(page))
2913 split++;
2914 unlock_page(page);
2915 next:
2916 put_page(page);
2917 }
2918 }
2919
2920 pr_info("%lu of %lu THP split\n", split, total);
2921
2922 return 0;
2923 }
2924 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2925 "%llu\n");
2926
2927 static int __init split_huge_pages_debugfs(void)
2928 {
2929 void *ret;
2930
2931 ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2932 &split_huge_pages_fops);
2933 if (!ret)
2934 pr_warn("Failed to create split_huge_pages in debugfs");
2935 return 0;
2936 }
2937 late_initcall(split_huge_pages_debugfs);
2938 #endif
2939
2940 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2941 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2942 struct page *page)
2943 {
2944 struct vm_area_struct *vma = pvmw->vma;
2945 struct mm_struct *mm = vma->vm_mm;
2946 unsigned long address = pvmw->address;
2947 pmd_t pmdval;
2948 swp_entry_t entry;
2949 pmd_t pmdswp;
2950
2951 if (!(pvmw->pmd && !pvmw->pte))
2952 return;
2953
2954 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2955 pmdval = *pvmw->pmd;
2956 pmdp_invalidate(vma, address, pvmw->pmd);
2957 if (pmd_dirty(pmdval))
2958 set_page_dirty(page);
2959 entry = make_migration_entry(page, pmd_write(pmdval));
2960 pmdswp = swp_entry_to_pmd(entry);
2961 if (pmd_soft_dirty(pmdval))
2962 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2963 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2964 page_remove_rmap(page, true);
2965 put_page(page);
2966 }
2967
2968 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2969 {
2970 struct vm_area_struct *vma = pvmw->vma;
2971 struct mm_struct *mm = vma->vm_mm;
2972 unsigned long address = pvmw->address;
2973 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2974 pmd_t pmde;
2975 swp_entry_t entry;
2976
2977 if (!(pvmw->pmd && !pvmw->pte))
2978 return;
2979
2980 entry = pmd_to_swp_entry(*pvmw->pmd);
2981 get_page(new);
2982 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2983 if (pmd_swp_soft_dirty(*pvmw->pmd))
2984 pmde = pmd_mksoft_dirty(pmde);
2985 if (is_write_migration_entry(entry))
2986 pmde = maybe_pmd_mkwrite(pmde, vma);
2987
2988 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2989 if (PageAnon(new))
2990 page_add_anon_rmap(new, vma, mmun_start, true);
2991 else
2992 page_add_file_rmap(new, true);
2993 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2994 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
2995 mlock_vma_page(new);
2996 update_mmu_cache_pmd(vma, address, pvmw->pmd);
2997 }
2998 #endif
2999
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