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TOMOYO Linux Cross Reference
Linux/mm/mempolicy.c

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  1 /*
  2  * Simple NUMA memory policy for the Linux kernel.
  3  *
  4  * Copyright 2003,2004 Andi Kleen, SuSE Labs.
  5  * (C) Copyright 2005 Christoph Lameter, Silicon Graphics, Inc.
  6  * Subject to the GNU Public License, version 2.
  7  *
  8  * NUMA policy allows the user to give hints in which node(s) memory should
  9  * be allocated.
 10  *
 11  * Support four policies per VMA and per process:
 12  *
 13  * The VMA policy has priority over the process policy for a page fault.
 14  *
 15  * interleave     Allocate memory interleaved over a set of nodes,
 16  *                with normal fallback if it fails.
 17  *                For VMA based allocations this interleaves based on the
 18  *                offset into the backing object or offset into the mapping
 19  *                for anonymous memory. For process policy an process counter
 20  *                is used.
 21  *
 22  * bind           Only allocate memory on a specific set of nodes,
 23  *                no fallback.
 24  *                FIXME: memory is allocated starting with the first node
 25  *                to the last. It would be better if bind would truly restrict
 26  *                the allocation to memory nodes instead
 27  *
 28  * preferred       Try a specific node first before normal fallback.
 29  *                As a special case NUMA_NO_NODE here means do the allocation
 30  *                on the local CPU. This is normally identical to default,
 31  *                but useful to set in a VMA when you have a non default
 32  *                process policy.
 33  *
 34  * default        Allocate on the local node first, or when on a VMA
 35  *                use the process policy. This is what Linux always did
 36  *                in a NUMA aware kernel and still does by, ahem, default.
 37  *
 38  * The process policy is applied for most non interrupt memory allocations
 39  * in that process' context. Interrupts ignore the policies and always
 40  * try to allocate on the local CPU. The VMA policy is only applied for memory
 41  * allocations for a VMA in the VM.
 42  *
 43  * Currently there are a few corner cases in swapping where the policy
 44  * is not applied, but the majority should be handled. When process policy
 45  * is used it is not remembered over swap outs/swap ins.
 46  *
 47  * Only the highest zone in the zone hierarchy gets policied. Allocations
 48  * requesting a lower zone just use default policy. This implies that
 49  * on systems with highmem kernel lowmem allocation don't get policied.
 50  * Same with GFP_DMA allocations.
 51  *
 52  * For shmfs/tmpfs/hugetlbfs shared memory the policy is shared between
 53  * all users and remembered even when nobody has memory mapped.
 54  */
 55 
 56 /* Notebook:
 57    fix mmap readahead to honour policy and enable policy for any page cache
 58    object
 59    statistics for bigpages
 60    global policy for page cache? currently it uses process policy. Requires
 61    first item above.
 62    handle mremap for shared memory (currently ignored for the policy)
 63    grows down?
 64    make bind policy root only? It can trigger oom much faster and the
 65    kernel is not always grateful with that.
 66 */
 67 
 68 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 69 
 70 #include <linux/mempolicy.h>
 71 #include <linux/mm.h>
 72 #include <linux/highmem.h>
 73 #include <linux/hugetlb.h>
 74 #include <linux/kernel.h>
 75 #include <linux/sched.h>
 76 #include <linux/nodemask.h>
 77 #include <linux/cpuset.h>
 78 #include <linux/slab.h>
 79 #include <linux/string.h>
 80 #include <linux/export.h>
 81 #include <linux/nsproxy.h>
 82 #include <linux/interrupt.h>
 83 #include <linux/init.h>
 84 #include <linux/compat.h>
 85 #include <linux/swap.h>
 86 #include <linux/seq_file.h>
 87 #include <linux/proc_fs.h>
 88 #include <linux/migrate.h>
 89 #include <linux/ksm.h>
 90 #include <linux/rmap.h>
 91 #include <linux/security.h>
 92 #include <linux/syscalls.h>
 93 #include <linux/ctype.h>
 94 #include <linux/mm_inline.h>
 95 #include <linux/mmu_notifier.h>
 96 #include <linux/printk.h>
 97 
 98 #include <asm/tlbflush.h>
 99 #include <asm/uaccess.h>
100 #include <linux/random.h>
101 
102 #include "internal.h"
103 
104 /* Internal flags */
105 #define MPOL_MF_DISCONTIG_OK (MPOL_MF_INTERNAL << 0)    /* Skip checks for continuous vmas */
106 #define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1)          /* Invert check for nodemask */
107 
108 static struct kmem_cache *policy_cache;
109 static struct kmem_cache *sn_cache;
110 
111 /* Highest zone. An specific allocation for a zone below that is not
112    policied. */
113 enum zone_type policy_zone = 0;
114 
115 /*
116  * run-time system-wide default policy => local allocation
117  */
118 static struct mempolicy default_policy = {
119         .refcnt = ATOMIC_INIT(1), /* never free it */
120         .mode = MPOL_PREFERRED,
121         .flags = MPOL_F_LOCAL,
122 };
123 
124 static struct mempolicy preferred_node_policy[MAX_NUMNODES];
125 
126 struct mempolicy *get_task_policy(struct task_struct *p)
127 {
128         struct mempolicy *pol = p->mempolicy;
129         int node;
130 
131         if (pol)
132                 return pol;
133 
134         node = numa_node_id();
135         if (node != NUMA_NO_NODE) {
136                 pol = &preferred_node_policy[node];
137                 /* preferred_node_policy is not initialised early in boot */
138                 if (pol->mode)
139                         return pol;
140         }
141 
142         return &default_policy;
143 }
144 
145 static const struct mempolicy_operations {
146         int (*create)(struct mempolicy *pol, const nodemask_t *nodes);
147         /*
148          * If read-side task has no lock to protect task->mempolicy, write-side
149          * task will rebind the task->mempolicy by two step. The first step is
150          * setting all the newly nodes, and the second step is cleaning all the
151          * disallowed nodes. In this way, we can avoid finding no node to alloc
152          * page.
153          * If we have a lock to protect task->mempolicy in read-side, we do
154          * rebind directly.
155          *
156          * step:
157          *      MPOL_REBIND_ONCE - do rebind work at once
158          *      MPOL_REBIND_STEP1 - set all the newly nodes
159          *      MPOL_REBIND_STEP2 - clean all the disallowed nodes
160          */
161         void (*rebind)(struct mempolicy *pol, const nodemask_t *nodes,
162                         enum mpol_rebind_step step);
163 } mpol_ops[MPOL_MAX];
164 
165 static inline int mpol_store_user_nodemask(const struct mempolicy *pol)
166 {
167         return pol->flags & MPOL_MODE_FLAGS;
168 }
169 
170 static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,
171                                    const nodemask_t *rel)
172 {
173         nodemask_t tmp;
174         nodes_fold(tmp, *orig, nodes_weight(*rel));
175         nodes_onto(*ret, tmp, *rel);
176 }
177 
178 static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes)
179 {
180         if (nodes_empty(*nodes))
181                 return -EINVAL;
182         pol->v.nodes = *nodes;
183         return 0;
184 }
185 
186 static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes)
187 {
188         if (!nodes)
189                 pol->flags |= MPOL_F_LOCAL;     /* local allocation */
190         else if (nodes_empty(*nodes))
191                 return -EINVAL;                 /*  no allowed nodes */
192         else
193                 pol->v.preferred_node = first_node(*nodes);
194         return 0;
195 }
196 
197 static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
198 {
199         if (nodes_empty(*nodes))
200                 return -EINVAL;
201         pol->v.nodes = *nodes;
202         return 0;
203 }
204 
205 /*
206  * mpol_set_nodemask is called after mpol_new() to set up the nodemask, if
207  * any, for the new policy.  mpol_new() has already validated the nodes
208  * parameter with respect to the policy mode and flags.  But, we need to
209  * handle an empty nodemask with MPOL_PREFERRED here.
210  *
211  * Must be called holding task's alloc_lock to protect task's mems_allowed
212  * and mempolicy.  May also be called holding the mmap_semaphore for write.
213  */
214 static int mpol_set_nodemask(struct mempolicy *pol,
215                      const nodemask_t *nodes, struct nodemask_scratch *nsc)
216 {
217         int ret;
218 
219         /* if mode is MPOL_DEFAULT, pol is NULL. This is right. */
220         if (pol == NULL)
221                 return 0;
222         /* Check N_MEMORY */
223         nodes_and(nsc->mask1,
224                   cpuset_current_mems_allowed, node_states[N_MEMORY]);
225 
226         VM_BUG_ON(!nodes);
227         if (pol->mode == MPOL_PREFERRED && nodes_empty(*nodes))
228                 nodes = NULL;   /* explicit local allocation */
229         else {
230                 if (pol->flags & MPOL_F_RELATIVE_NODES)
231                         mpol_relative_nodemask(&nsc->mask2, nodes, &nsc->mask1);
232                 else
233                         nodes_and(nsc->mask2, *nodes, nsc->mask1);
234 
235                 if (mpol_store_user_nodemask(pol))
236                         pol->w.user_nodemask = *nodes;
237                 else
238                         pol->w.cpuset_mems_allowed =
239                                                 cpuset_current_mems_allowed;
240         }
241 
242         if (nodes)
243                 ret = mpol_ops[pol->mode].create(pol, &nsc->mask2);
244         else
245                 ret = mpol_ops[pol->mode].create(pol, NULL);
246         return ret;
247 }
248 
249 /*
250  * This function just creates a new policy, does some check and simple
251  * initialization. You must invoke mpol_set_nodemask() to set nodes.
252  */
253 static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
254                                   nodemask_t *nodes)
255 {
256         struct mempolicy *policy;
257 
258         pr_debug("setting mode %d flags %d nodes[0] %lx\n",
259                  mode, flags, nodes ? nodes_addr(*nodes)[0] : NUMA_NO_NODE);
260 
261         if (mode == MPOL_DEFAULT) {
262                 if (nodes && !nodes_empty(*nodes))
263                         return ERR_PTR(-EINVAL);
264                 return NULL;
265         }
266         VM_BUG_ON(!nodes);
267 
268         /*
269          * MPOL_PREFERRED cannot be used with MPOL_F_STATIC_NODES or
270          * MPOL_F_RELATIVE_NODES if the nodemask is empty (local allocation).
271          * All other modes require a valid pointer to a non-empty nodemask.
272          */
273         if (mode == MPOL_PREFERRED) {
274                 if (nodes_empty(*nodes)) {
275                         if (((flags & MPOL_F_STATIC_NODES) ||
276                              (flags & MPOL_F_RELATIVE_NODES)))
277                                 return ERR_PTR(-EINVAL);
278                 }
279         } else if (mode == MPOL_LOCAL) {
280                 if (!nodes_empty(*nodes))
281                         return ERR_PTR(-EINVAL);
282                 mode = MPOL_PREFERRED;
283         } else if (nodes_empty(*nodes))
284                 return ERR_PTR(-EINVAL);
285         policy = kmem_cache_alloc(policy_cache, GFP_KERNEL);
286         if (!policy)
287                 return ERR_PTR(-ENOMEM);
288         atomic_set(&policy->refcnt, 1);
289         policy->mode = mode;
290         policy->flags = flags;
291 
292         return policy;
293 }
294 
295 /* Slow path of a mpol destructor. */
296 void __mpol_put(struct mempolicy *p)
297 {
298         if (!atomic_dec_and_test(&p->refcnt))
299                 return;
300         kmem_cache_free(policy_cache, p);
301 }
302 
303 static void mpol_rebind_default(struct mempolicy *pol, const nodemask_t *nodes,
304                                 enum mpol_rebind_step step)
305 {
306 }
307 
308 /*
309  * step:
310  *      MPOL_REBIND_ONCE  - do rebind work at once
311  *      MPOL_REBIND_STEP1 - set all the newly nodes
312  *      MPOL_REBIND_STEP2 - clean all the disallowed nodes
313  */
314 static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes,
315                                  enum mpol_rebind_step step)
316 {
317         nodemask_t tmp;
318 
319         if (pol->flags & MPOL_F_STATIC_NODES)
320                 nodes_and(tmp, pol->w.user_nodemask, *nodes);
321         else if (pol->flags & MPOL_F_RELATIVE_NODES)
322                 mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
323         else {
324                 /*
325                  * if step == 1, we use ->w.cpuset_mems_allowed to cache the
326                  * result
327                  */
328                 if (step == MPOL_REBIND_ONCE || step == MPOL_REBIND_STEP1) {
329                         nodes_remap(tmp, pol->v.nodes,
330                                         pol->w.cpuset_mems_allowed, *nodes);
331                         pol->w.cpuset_mems_allowed = step ? tmp : *nodes;
332                 } else if (step == MPOL_REBIND_STEP2) {
333                         tmp = pol->w.cpuset_mems_allowed;
334                         pol->w.cpuset_mems_allowed = *nodes;
335                 } else
336                         BUG();
337         }
338 
339         if (nodes_empty(tmp))
340                 tmp = *nodes;
341 
342         if (step == MPOL_REBIND_STEP1)
343                 nodes_or(pol->v.nodes, pol->v.nodes, tmp);
344         else if (step == MPOL_REBIND_ONCE || step == MPOL_REBIND_STEP2)
345                 pol->v.nodes = tmp;
346         else
347                 BUG();
348 
349         if (!node_isset(current->il_next, tmp)) {
350                 current->il_next = next_node(current->il_next, tmp);
351                 if (current->il_next >= MAX_NUMNODES)
352                         current->il_next = first_node(tmp);
353                 if (current->il_next >= MAX_NUMNODES)
354                         current->il_next = numa_node_id();
355         }
356 }
357 
358 static void mpol_rebind_preferred(struct mempolicy *pol,
359                                   const nodemask_t *nodes,
360                                   enum mpol_rebind_step step)
361 {
362         nodemask_t tmp;
363 
364         if (pol->flags & MPOL_F_STATIC_NODES) {
365                 int node = first_node(pol->w.user_nodemask);
366 
367                 if (node_isset(node, *nodes)) {
368                         pol->v.preferred_node = node;
369                         pol->flags &= ~MPOL_F_LOCAL;
370                 } else
371                         pol->flags |= MPOL_F_LOCAL;
372         } else if (pol->flags & MPOL_F_RELATIVE_NODES) {
373                 mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
374                 pol->v.preferred_node = first_node(tmp);
375         } else if (!(pol->flags & MPOL_F_LOCAL)) {
376                 pol->v.preferred_node = node_remap(pol->v.preferred_node,
377                                                    pol->w.cpuset_mems_allowed,
378                                                    *nodes);
379                 pol->w.cpuset_mems_allowed = *nodes;
380         }
381 }
382 
383 /*
384  * mpol_rebind_policy - Migrate a policy to a different set of nodes
385  *
386  * If read-side task has no lock to protect task->mempolicy, write-side
387  * task will rebind the task->mempolicy by two step. The first step is
388  * setting all the newly nodes, and the second step is cleaning all the
389  * disallowed nodes. In this way, we can avoid finding no node to alloc
390  * page.
391  * If we have a lock to protect task->mempolicy in read-side, we do
392  * rebind directly.
393  *
394  * step:
395  *      MPOL_REBIND_ONCE  - do rebind work at once
396  *      MPOL_REBIND_STEP1 - set all the newly nodes
397  *      MPOL_REBIND_STEP2 - clean all the disallowed nodes
398  */
399 static void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *newmask,
400                                 enum mpol_rebind_step step)
401 {
402         if (!pol)
403                 return;
404         if (!mpol_store_user_nodemask(pol) && step == MPOL_REBIND_ONCE &&
405             nodes_equal(pol->w.cpuset_mems_allowed, *newmask))
406                 return;
407 
408         if (step == MPOL_REBIND_STEP1 && (pol->flags & MPOL_F_REBINDING))
409                 return;
410 
411         if (step == MPOL_REBIND_STEP2 && !(pol->flags & MPOL_F_REBINDING))
412                 BUG();
413 
414         if (step == MPOL_REBIND_STEP1)
415                 pol->flags |= MPOL_F_REBINDING;
416         else if (step == MPOL_REBIND_STEP2)
417                 pol->flags &= ~MPOL_F_REBINDING;
418         else if (step >= MPOL_REBIND_NSTEP)
419                 BUG();
420 
421         mpol_ops[pol->mode].rebind(pol, newmask, step);
422 }
423 
424 /*
425  * Wrapper for mpol_rebind_policy() that just requires task
426  * pointer, and updates task mempolicy.
427  *
428  * Called with task's alloc_lock held.
429  */
430 
431 void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new,
432                         enum mpol_rebind_step step)
433 {
434         mpol_rebind_policy(tsk->mempolicy, new, step);
435 }
436 
437 /*
438  * Rebind each vma in mm to new nodemask.
439  *
440  * Call holding a reference to mm.  Takes mm->mmap_sem during call.
441  */
442 
443 void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
444 {
445         struct vm_area_struct *vma;
446 
447         down_write(&mm->mmap_sem);
448         for (vma = mm->mmap; vma; vma = vma->vm_next)
449                 mpol_rebind_policy(vma->vm_policy, new, MPOL_REBIND_ONCE);
450         up_write(&mm->mmap_sem);
451 }
452 
453 static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
454         [MPOL_DEFAULT] = {
455                 .rebind = mpol_rebind_default,
456         },
457         [MPOL_INTERLEAVE] = {
458                 .create = mpol_new_interleave,
459                 .rebind = mpol_rebind_nodemask,
460         },
461         [MPOL_PREFERRED] = {
462                 .create = mpol_new_preferred,
463                 .rebind = mpol_rebind_preferred,
464         },
465         [MPOL_BIND] = {
466                 .create = mpol_new_bind,
467                 .rebind = mpol_rebind_nodemask,
468         },
469 };
470 
471 static void migrate_page_add(struct page *page, struct list_head *pagelist,
472                                 unsigned long flags);
473 
474 struct queue_pages {
475         struct list_head *pagelist;
476         unsigned long flags;
477         nodemask_t *nmask;
478         struct vm_area_struct *prev;
479 };
480 
481 /*
482  * Scan through pages checking if pages follow certain conditions,
483  * and move them to the pagelist if they do.
484  */
485 static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
486                         unsigned long end, struct mm_walk *walk)
487 {
488         struct vm_area_struct *vma = walk->vma;
489         struct page *page;
490         struct queue_pages *qp = walk->private;
491         unsigned long flags = qp->flags;
492         int nid;
493         pte_t *pte;
494         spinlock_t *ptl;
495 
496         split_huge_page_pmd(vma, addr, pmd);
497         if (pmd_trans_unstable(pmd))
498                 return 0;
499 
500         pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
501         for (; addr != end; pte++, addr += PAGE_SIZE) {
502                 if (!pte_present(*pte))
503                         continue;
504                 page = vm_normal_page(vma, addr, *pte);
505                 if (!page)
506                         continue;
507                 /*
508                  * vm_normal_page() filters out zero pages, but there might
509                  * still be PageReserved pages to skip, perhaps in a VDSO.
510                  */
511                 if (PageReserved(page))
512                         continue;
513                 nid = page_to_nid(page);
514                 if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
515                         continue;
516 
517                 if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
518                         migrate_page_add(page, qp->pagelist, flags);
519         }
520         pte_unmap_unlock(pte - 1, ptl);
521         cond_resched();
522         return 0;
523 }
524 
525 static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
526                                unsigned long addr, unsigned long end,
527                                struct mm_walk *walk)
528 {
529 #ifdef CONFIG_HUGETLB_PAGE
530         struct queue_pages *qp = walk->private;
531         unsigned long flags = qp->flags;
532         int nid;
533         struct page *page;
534         spinlock_t *ptl;
535         pte_t entry;
536 
537         ptl = huge_pte_lock(hstate_vma(walk->vma), walk->mm, pte);
538         entry = huge_ptep_get(pte);
539         if (!pte_present(entry))
540                 goto unlock;
541         page = pte_page(entry);
542         nid = page_to_nid(page);
543         if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
544                 goto unlock;
545         /* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
546         if (flags & (MPOL_MF_MOVE_ALL) ||
547             (flags & MPOL_MF_MOVE && page_mapcount(page) == 1))
548                 isolate_huge_page(page, qp->pagelist);
549 unlock:
550         spin_unlock(ptl);
551 #else
552         BUG();
553 #endif
554         return 0;
555 }
556 
557 #ifdef CONFIG_NUMA_BALANCING
558 /*
559  * This is used to mark a range of virtual addresses to be inaccessible.
560  * These are later cleared by a NUMA hinting fault. Depending on these
561  * faults, pages may be migrated for better NUMA placement.
562  *
563  * This is assuming that NUMA faults are handled using PROT_NONE. If
564  * an architecture makes a different choice, it will need further
565  * changes to the core.
566  */
567 unsigned long change_prot_numa(struct vm_area_struct *vma,
568                         unsigned long addr, unsigned long end)
569 {
570         int nr_updated;
571 
572         nr_updated = change_protection(vma, addr, end, PAGE_NONE, 0, 1);
573         if (nr_updated)
574                 count_vm_numa_events(NUMA_PTE_UPDATES, nr_updated);
575 
576         return nr_updated;
577 }
578 #else
579 static unsigned long change_prot_numa(struct vm_area_struct *vma,
580                         unsigned long addr, unsigned long end)
581 {
582         return 0;
583 }
584 #endif /* CONFIG_NUMA_BALANCING */
585 
586 static int queue_pages_test_walk(unsigned long start, unsigned long end,
587                                 struct mm_walk *walk)
588 {
589         struct vm_area_struct *vma = walk->vma;
590         struct queue_pages *qp = walk->private;
591         unsigned long endvma = vma->vm_end;
592         unsigned long flags = qp->flags;
593 
594         if (vma->vm_flags & VM_PFNMAP)
595                 return 1;
596 
597         if (endvma > end)
598                 endvma = end;
599         if (vma->vm_start > start)
600                 start = vma->vm_start;
601 
602         if (!(flags & MPOL_MF_DISCONTIG_OK)) {
603                 if (!vma->vm_next && vma->vm_end < end)
604                         return -EFAULT;
605                 if (qp->prev && qp->prev->vm_end < vma->vm_start)
606                         return -EFAULT;
607         }
608 
609         qp->prev = vma;
610 
611         if (flags & MPOL_MF_LAZY) {
612                 /* Similar to task_numa_work, skip inaccessible VMAs */
613                 if (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))
614                         change_prot_numa(vma, start, endvma);
615                 return 1;
616         }
617 
618         if ((flags & MPOL_MF_STRICT) ||
619             ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
620              vma_migratable(vma)))
621                 /* queue pages from current vma */
622                 return 0;
623         return 1;
624 }
625 
626 /*
627  * Walk through page tables and collect pages to be migrated.
628  *
629  * If pages found in a given range are on a set of nodes (determined by
630  * @nodes and @flags,) it's isolated and queued to the pagelist which is
631  * passed via @private.)
632  */
633 static int
634 queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
635                 nodemask_t *nodes, unsigned long flags,
636                 struct list_head *pagelist)
637 {
638         struct queue_pages qp = {
639                 .pagelist = pagelist,
640                 .flags = flags,
641                 .nmask = nodes,
642                 .prev = NULL,
643         };
644         struct mm_walk queue_pages_walk = {
645                 .hugetlb_entry = queue_pages_hugetlb,
646                 .pmd_entry = queue_pages_pte_range,
647                 .test_walk = queue_pages_test_walk,
648                 .mm = mm,
649                 .private = &qp,
650         };
651 
652         return walk_page_range(start, end, &queue_pages_walk);
653 }
654 
655 /*
656  * Apply policy to a single VMA
657  * This must be called with the mmap_sem held for writing.
658  */
659 static int vma_replace_policy(struct vm_area_struct *vma,
660                                                 struct mempolicy *pol)
661 {
662         int err;
663         struct mempolicy *old;
664         struct mempolicy *new;
665 
666         pr_debug("vma %lx-%lx/%lx vm_ops %p vm_file %p set_policy %p\n",
667                  vma->vm_start, vma->vm_end, vma->vm_pgoff,
668                  vma->vm_ops, vma->vm_file,
669                  vma->vm_ops ? vma->vm_ops->set_policy : NULL);
670 
671         new = mpol_dup(pol);
672         if (IS_ERR(new))
673                 return PTR_ERR(new);
674 
675         if (vma->vm_ops && vma->vm_ops->set_policy) {
676                 err = vma->vm_ops->set_policy(vma, new);
677                 if (err)
678                         goto err_out;
679         }
680 
681         old = vma->vm_policy;
682         vma->vm_policy = new; /* protected by mmap_sem */
683         mpol_put(old);
684 
685         return 0;
686  err_out:
687         mpol_put(new);
688         return err;
689 }
690 
691 /* Step 2: apply policy to a range and do splits. */
692 static int mbind_range(struct mm_struct *mm, unsigned long start,
693                        unsigned long end, struct mempolicy *new_pol)
694 {
695         struct vm_area_struct *next;
696         struct vm_area_struct *prev;
697         struct vm_area_struct *vma;
698         int err = 0;
699         pgoff_t pgoff;
700         unsigned long vmstart;
701         unsigned long vmend;
702 
703         vma = find_vma(mm, start);
704         if (!vma || vma->vm_start > start)
705                 return -EFAULT;
706 
707         prev = vma->vm_prev;
708         if (start > vma->vm_start)
709                 prev = vma;
710 
711         for (; vma && vma->vm_start < end; prev = vma, vma = next) {
712                 next = vma->vm_next;
713                 vmstart = max(start, vma->vm_start);
714                 vmend   = min(end, vma->vm_end);
715 
716                 if (mpol_equal(vma_policy(vma), new_pol))
717                         continue;
718 
719                 pgoff = vma->vm_pgoff +
720                         ((vmstart - vma->vm_start) >> PAGE_SHIFT);
721                 prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
722                                  vma->anon_vma, vma->vm_file, pgoff,
723                                  new_pol, vma->vm_userfaultfd_ctx);
724                 if (prev) {
725                         vma = prev;
726                         next = vma->vm_next;
727                         if (mpol_equal(vma_policy(vma), new_pol))
728                                 continue;
729                         /* vma_merge() joined vma && vma->next, case 8 */
730                         goto replace;
731                 }
732                 if (vma->vm_start != vmstart) {
733                         err = split_vma(vma->vm_mm, vma, vmstart, 1);
734                         if (err)
735                                 goto out;
736                 }
737                 if (vma->vm_end != vmend) {
738                         err = split_vma(vma->vm_mm, vma, vmend, 0);
739                         if (err)
740                                 goto out;
741                 }
742  replace:
743                 err = vma_replace_policy(vma, new_pol);
744                 if (err)
745                         goto out;
746         }
747 
748  out:
749         return err;
750 }
751 
752 /* Set the process memory policy */
753 static long do_set_mempolicy(unsigned short mode, unsigned short flags,
754                              nodemask_t *nodes)
755 {
756         struct mempolicy *new, *old;
757         NODEMASK_SCRATCH(scratch);
758         int ret;
759 
760         if (!scratch)
761                 return -ENOMEM;
762 
763         new = mpol_new(mode, flags, nodes);
764         if (IS_ERR(new)) {
765                 ret = PTR_ERR(new);
766                 goto out;
767         }
768 
769         task_lock(current);
770         ret = mpol_set_nodemask(new, nodes, scratch);
771         if (ret) {
772                 task_unlock(current);
773                 mpol_put(new);
774                 goto out;
775         }
776         old = current->mempolicy;
777         current->mempolicy = new;
778         if (new && new->mode == MPOL_INTERLEAVE &&
779             nodes_weight(new->v.nodes))
780                 current->il_next = first_node(new->v.nodes);
781         task_unlock(current);
782         mpol_put(old);
783         ret = 0;
784 out:
785         NODEMASK_SCRATCH_FREE(scratch);
786         return ret;
787 }
788 
789 /*
790  * Return nodemask for policy for get_mempolicy() query
791  *
792  * Called with task's alloc_lock held
793  */
794 static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
795 {
796         nodes_clear(*nodes);
797         if (p == &default_policy)
798                 return;
799 
800         switch (p->mode) {
801         case MPOL_BIND:
802                 /* Fall through */
803         case MPOL_INTERLEAVE:
804                 *nodes = p->v.nodes;
805                 break;
806         case MPOL_PREFERRED:
807                 if (!(p->flags & MPOL_F_LOCAL))
808                         node_set(p->v.preferred_node, *nodes);
809                 /* else return empty node mask for local allocation */
810                 break;
811         default:
812                 BUG();
813         }
814 }
815 
816 static int lookup_node(struct mm_struct *mm, unsigned long addr)
817 {
818         struct page *p;
819         int err;
820 
821         err = get_user_pages(current, mm, addr & PAGE_MASK, 1, 0, 0, &p, NULL);
822         if (err >= 0) {
823                 err = page_to_nid(p);
824                 put_page(p);
825         }
826         return err;
827 }
828 
829 /* Retrieve NUMA policy */
830 static long do_get_mempolicy(int *policy, nodemask_t *nmask,
831                              unsigned long addr, unsigned long flags)
832 {
833         int err;
834         struct mm_struct *mm = current->mm;
835         struct vm_area_struct *vma = NULL;
836         struct mempolicy *pol = current->mempolicy;
837 
838         if (flags &
839                 ~(unsigned long)(MPOL_F_NODE|MPOL_F_ADDR|MPOL_F_MEMS_ALLOWED))
840                 return -EINVAL;
841 
842         if (flags & MPOL_F_MEMS_ALLOWED) {
843                 if (flags & (MPOL_F_NODE|MPOL_F_ADDR))
844                         return -EINVAL;
845                 *policy = 0;    /* just so it's initialized */
846                 task_lock(current);
847                 *nmask  = cpuset_current_mems_allowed;
848                 task_unlock(current);
849                 return 0;
850         }
851 
852         if (flags & MPOL_F_ADDR) {
853                 /*
854                  * Do NOT fall back to task policy if the
855                  * vma/shared policy at addr is NULL.  We
856                  * want to return MPOL_DEFAULT in this case.
857                  */
858                 down_read(&mm->mmap_sem);
859                 vma = find_vma_intersection(mm, addr, addr+1);
860                 if (!vma) {
861                         up_read(&mm->mmap_sem);
862                         return -EFAULT;
863                 }
864                 if (vma->vm_ops && vma->vm_ops->get_policy)
865                         pol = vma->vm_ops->get_policy(vma, addr);
866                 else
867                         pol = vma->vm_policy;
868         } else if (addr)
869                 return -EINVAL;
870 
871         if (!pol)
872                 pol = &default_policy;  /* indicates default behavior */
873 
874         if (flags & MPOL_F_NODE) {
875                 if (flags & MPOL_F_ADDR) {
876                         err = lookup_node(mm, addr);
877                         if (err < 0)
878                                 goto out;
879                         *policy = err;
880                 } else if (pol == current->mempolicy &&
881                                 pol->mode == MPOL_INTERLEAVE) {
882                         *policy = current->il_next;
883                 } else {
884                         err = -EINVAL;
885                         goto out;
886                 }
887         } else {
888                 *policy = pol == &default_policy ? MPOL_DEFAULT :
889                                                 pol->mode;
890                 /*
891                  * Internal mempolicy flags must be masked off before exposing
892                  * the policy to userspace.
893                  */
894                 *policy |= (pol->flags & MPOL_MODE_FLAGS);
895         }
896 
897         if (vma) {
898                 up_read(&current->mm->mmap_sem);
899                 vma = NULL;
900         }
901 
902         err = 0;
903         if (nmask) {
904                 if (mpol_store_user_nodemask(pol)) {
905                         *nmask = pol->w.user_nodemask;
906                 } else {
907                         task_lock(current);
908                         get_policy_nodemask(pol, nmask);
909                         task_unlock(current);
910                 }
911         }
912 
913  out:
914         mpol_cond_put(pol);
915         if (vma)
916                 up_read(&current->mm->mmap_sem);
917         return err;
918 }
919 
920 #ifdef CONFIG_MIGRATION
921 /*
922  * page migration
923  */
924 static void migrate_page_add(struct page *page, struct list_head *pagelist,
925                                 unsigned long flags)
926 {
927         /*
928          * Avoid migrating a page that is shared with others.
929          */
930         if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(page) == 1) {
931                 if (!isolate_lru_page(page)) {
932                         list_add_tail(&page->lru, pagelist);
933                         inc_zone_page_state(page, NR_ISOLATED_ANON +
934                                             page_is_file_cache(page));
935                 }
936         }
937 }
938 
939 static struct page *new_node_page(struct page *page, unsigned long node, int **x)
940 {
941         if (PageHuge(page))
942                 return alloc_huge_page_node(page_hstate(compound_head(page)),
943                                         node);
944         else
945                 return __alloc_pages_node(node, GFP_HIGHUSER_MOVABLE |
946                                                     __GFP_THISNODE, 0);
947 }
948 
949 /*
950  * Migrate pages from one node to a target node.
951  * Returns error or the number of pages not migrated.
952  */
953 static int migrate_to_node(struct mm_struct *mm, int source, int dest,
954                            int flags)
955 {
956         nodemask_t nmask;
957         LIST_HEAD(pagelist);
958         int err = 0;
959 
960         nodes_clear(nmask);
961         node_set(source, nmask);
962 
963         /*
964          * This does not "check" the range but isolates all pages that
965          * need migration.  Between passing in the full user address
966          * space range and MPOL_MF_DISCONTIG_OK, this call can not fail.
967          */
968         VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)));
969         queue_pages_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
970                         flags | MPOL_MF_DISCONTIG_OK, &pagelist);
971 
972         if (!list_empty(&pagelist)) {
973                 err = migrate_pages(&pagelist, new_node_page, NULL, dest,
974                                         MIGRATE_SYNC, MR_SYSCALL);
975                 if (err)
976                         putback_movable_pages(&pagelist);
977         }
978 
979         return err;
980 }
981 
982 /*
983  * Move pages between the two nodesets so as to preserve the physical
984  * layout as much as possible.
985  *
986  * Returns the number of page that could not be moved.
987  */
988 int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
989                      const nodemask_t *to, int flags)
990 {
991         int busy = 0;
992         int err;
993         nodemask_t tmp;
994 
995         err = migrate_prep();
996         if (err)
997                 return err;
998 
999         down_read(&mm->mmap_sem);
1000 
1001         /*
1002          * Find a 'source' bit set in 'tmp' whose corresponding 'dest'
1003          * bit in 'to' is not also set in 'tmp'.  Clear the found 'source'
1004          * bit in 'tmp', and return that <source, dest> pair for migration.
1005          * The pair of nodemasks 'to' and 'from' define the map.
1006          *
1007          * If no pair of bits is found that way, fallback to picking some
1008          * pair of 'source' and 'dest' bits that are not the same.  If the
1009          * 'source' and 'dest' bits are the same, this represents a node
1010          * that will be migrating to itself, so no pages need move.
1011          *
1012          * If no bits are left in 'tmp', or if all remaining bits left
1013          * in 'tmp' correspond to the same bit in 'to', return false
1014          * (nothing left to migrate).
1015          *
1016          * This lets us pick a pair of nodes to migrate between, such that
1017          * if possible the dest node is not already occupied by some other
1018          * source node, minimizing the risk of overloading the memory on a
1019          * node that would happen if we migrated incoming memory to a node
1020          * before migrating outgoing memory source that same node.
1021          *
1022          * A single scan of tmp is sufficient.  As we go, we remember the
1023          * most recent <s, d> pair that moved (s != d).  If we find a pair
1024          * that not only moved, but what's better, moved to an empty slot
1025          * (d is not set in tmp), then we break out then, with that pair.
1026          * Otherwise when we finish scanning from_tmp, we at least have the
1027          * most recent <s, d> pair that moved.  If we get all the way through
1028          * the scan of tmp without finding any node that moved, much less
1029          * moved to an empty node, then there is nothing left worth migrating.
1030          */
1031 
1032         tmp = *from;
1033         while (!nodes_empty(tmp)) {
1034                 int s,d;
1035                 int source = NUMA_NO_NODE;
1036                 int dest = 0;
1037 
1038                 for_each_node_mask(s, tmp) {
1039 
1040                         /*
1041                          * do_migrate_pages() tries to maintain the relative
1042                          * node relationship of the pages established between
1043                          * threads and memory areas.
1044                          *
1045                          * However if the number of source nodes is not equal to
1046                          * the number of destination nodes we can not preserve
1047                          * this node relative relationship.  In that case, skip
1048                          * copying memory from a node that is in the destination
1049                          * mask.
1050                          *
1051                          * Example: [2,3,4] -> [3,4,5] moves everything.
1052                          *          [0-7] - > [3,4,5] moves only 0,1,2,6,7.
1053                          */
1054 
1055                         if ((nodes_weight(*from) != nodes_weight(*to)) &&
1056                                                 (node_isset(s, *to)))
1057                                 continue;
1058 
1059                         d = node_remap(s, *from, *to);
1060                         if (s == d)
1061                                 continue;
1062 
1063                         source = s;     /* Node moved. Memorize */
1064                         dest = d;
1065 
1066                         /* dest not in remaining from nodes? */
1067                         if (!node_isset(dest, tmp))
1068                                 break;
1069                 }
1070                 if (source == NUMA_NO_NODE)
1071                         break;
1072 
1073                 node_clear(source, tmp);
1074                 err = migrate_to_node(mm, source, dest, flags);
1075                 if (err > 0)
1076                         busy += err;
1077                 if (err < 0)
1078                         break;
1079         }
1080         up_read(&mm->mmap_sem);
1081         if (err < 0)
1082                 return err;
1083         return busy;
1084 
1085 }
1086 
1087 /*
1088  * Allocate a new page for page migration based on vma policy.
1089  * Start by assuming the page is mapped by the same vma as contains @start.
1090  * Search forward from there, if not.  N.B., this assumes that the
1091  * list of pages handed to migrate_pages()--which is how we get here--
1092  * is in virtual address order.
1093  */
1094 static struct page *new_page(struct page *page, unsigned long start, int **x)
1095 {
1096         struct vm_area_struct *vma;
1097         unsigned long uninitialized_var(address);
1098 
1099         vma = find_vma(current->mm, start);
1100         while (vma) {
1101                 address = page_address_in_vma(page, vma);
1102                 if (address != -EFAULT)
1103                         break;
1104                 vma = vma->vm_next;
1105         }
1106 
1107         if (PageHuge(page)) {
1108                 BUG_ON(!vma);
1109                 return alloc_huge_page_noerr(vma, address, 1);
1110         }
1111         /*
1112          * if !vma, alloc_page_vma() will use task or system default policy
1113          */
1114         return alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
1115 }
1116 #else
1117 
1118 static void migrate_page_add(struct page *page, struct list_head *pagelist,
1119                                 unsigned long flags)
1120 {
1121 }
1122 
1123 int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
1124                      const nodemask_t *to, int flags)
1125 {
1126         return -ENOSYS;
1127 }
1128 
1129 static struct page *new_page(struct page *page, unsigned long start, int **x)
1130 {
1131         return NULL;
1132 }
1133 #endif
1134 
1135 static long do_mbind(unsigned long start, unsigned long len,
1136                      unsigned short mode, unsigned short mode_flags,
1137                      nodemask_t *nmask, unsigned long flags)
1138 {
1139         struct mm_struct *mm = current->mm;
1140         struct mempolicy *new;
1141         unsigned long end;
1142         int err;
1143         LIST_HEAD(pagelist);
1144 
1145         if (flags & ~(unsigned long)MPOL_MF_VALID)
1146                 return -EINVAL;
1147         if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1148                 return -EPERM;
1149 
1150         if (start & ~PAGE_MASK)
1151                 return -EINVAL;
1152 
1153         if (mode == MPOL_DEFAULT)
1154                 flags &= ~MPOL_MF_STRICT;
1155 
1156         len = (len + PAGE_SIZE - 1) & PAGE_MASK;
1157         end = start + len;
1158 
1159         if (end < start)
1160                 return -EINVAL;
1161         if (end == start)
1162                 return 0;
1163 
1164         new = mpol_new(mode, mode_flags, nmask);
1165         if (IS_ERR(new))
1166                 return PTR_ERR(new);
1167 
1168         if (flags & MPOL_MF_LAZY)
1169                 new->flags |= MPOL_F_MOF;
1170 
1171         /*
1172          * If we are using the default policy then operation
1173          * on discontinuous address spaces is okay after all
1174          */
1175         if (!new)
1176                 flags |= MPOL_MF_DISCONTIG_OK;
1177 
1178         pr_debug("mbind %lx-%lx mode:%d flags:%d nodes:%lx\n",
1179                  start, start + len, mode, mode_flags,
1180                  nmask ? nodes_addr(*nmask)[0] : NUMA_NO_NODE);
1181 
1182         if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
1183 
1184                 err = migrate_prep();
1185                 if (err)
1186                         goto mpol_out;
1187         }
1188         {
1189                 NODEMASK_SCRATCH(scratch);
1190                 if (scratch) {
1191                         down_write(&mm->mmap_sem);
1192                         task_lock(current);
1193                         err = mpol_set_nodemask(new, nmask, scratch);
1194                         task_unlock(current);
1195                         if (err)
1196                                 up_write(&mm->mmap_sem);
1197                 } else
1198                         err = -ENOMEM;
1199                 NODEMASK_SCRATCH_FREE(scratch);
1200         }
1201         if (err)
1202                 goto mpol_out;
1203 
1204         err = queue_pages_range(mm, start, end, nmask,
1205                           flags | MPOL_MF_INVERT, &pagelist);
1206         if (!err)
1207                 err = mbind_range(mm, start, end, new);
1208 
1209         if (!err) {
1210                 int nr_failed = 0;
1211 
1212                 if (!list_empty(&pagelist)) {
1213                         WARN_ON_ONCE(flags & MPOL_MF_LAZY);
1214                         nr_failed = migrate_pages(&pagelist, new_page, NULL,
1215                                 start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND);
1216                         if (nr_failed)
1217                                 putback_movable_pages(&pagelist);
1218                 }
1219 
1220                 if (nr_failed && (flags & MPOL_MF_STRICT))
1221                         err = -EIO;
1222         } else
1223                 putback_movable_pages(&pagelist);
1224 
1225         up_write(&mm->mmap_sem);
1226  mpol_out:
1227         mpol_put(new);
1228         return err;
1229 }
1230 
1231 /*
1232  * User space interface with variable sized bitmaps for nodelists.
1233  */
1234 
1235 /* Copy a node mask from user space. */
1236 static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask,
1237                      unsigned long maxnode)
1238 {
1239         unsigned long k;
1240         unsigned long nlongs;
1241         unsigned long endmask;
1242 
1243         --maxnode;
1244         nodes_clear(*nodes);
1245         if (maxnode == 0 || !nmask)
1246                 return 0;
1247         if (maxnode > PAGE_SIZE*BITS_PER_BYTE)
1248                 return -EINVAL;
1249 
1250         nlongs = BITS_TO_LONGS(maxnode);
1251         if ((maxnode % BITS_PER_LONG) == 0)
1252                 endmask = ~0UL;
1253         else
1254                 endmask = (1UL << (maxnode % BITS_PER_LONG)) - 1;
1255 
1256         /* When the user specified more nodes than supported just check
1257            if the non supported part is all zero. */
1258         if (nlongs > BITS_TO_LONGS(MAX_NUMNODES)) {
1259                 if (nlongs > PAGE_SIZE/sizeof(long))
1260                         return -EINVAL;
1261                 for (k = BITS_TO_LONGS(MAX_NUMNODES); k < nlongs; k++) {
1262                         unsigned long t;
1263                         if (get_user(t, nmask + k))
1264                                 return -EFAULT;
1265                         if (k == nlongs - 1) {
1266                                 if (t & endmask)
1267                                         return -EINVAL;
1268                         } else if (t)
1269                                 return -EINVAL;
1270                 }
1271                 nlongs = BITS_TO_LONGS(MAX_NUMNODES);
1272                 endmask = ~0UL;
1273         }
1274 
1275         if (copy_from_user(nodes_addr(*nodes), nmask, nlongs*sizeof(unsigned long)))
1276                 return -EFAULT;
1277         nodes_addr(*nodes)[nlongs-1] &= endmask;
1278         return 0;
1279 }
1280 
1281 /* Copy a kernel node mask to user space */
1282 static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
1283                               nodemask_t *nodes)
1284 {
1285         unsigned long copy = ALIGN(maxnode-1, 64) / 8;
1286         const int nbytes = BITS_TO_LONGS(MAX_NUMNODES) * sizeof(long);
1287 
1288         if (copy > nbytes) {
1289                 if (copy > PAGE_SIZE)
1290                         return -EINVAL;
1291                 if (clear_user((char __user *)mask + nbytes, copy - nbytes))
1292                         return -EFAULT;
1293                 copy = nbytes;
1294         }
1295         return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0;
1296 }
1297 
1298 SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
1299                 unsigned long, mode, const unsigned long __user *, nmask,
1300                 unsigned long, maxnode, unsigned, flags)
1301 {
1302         nodemask_t nodes;
1303         int err;
1304         unsigned short mode_flags;
1305 
1306         mode_flags = mode & MPOL_MODE_FLAGS;
1307         mode &= ~MPOL_MODE_FLAGS;
1308         if (mode >= MPOL_MAX)
1309                 return -EINVAL;
1310         if ((mode_flags & MPOL_F_STATIC_NODES) &&
1311             (mode_flags & MPOL_F_RELATIVE_NODES))
1312                 return -EINVAL;
1313         err = get_nodes(&nodes, nmask, maxnode);
1314         if (err)
1315                 return err;
1316         return do_mbind(start, len, mode, mode_flags, &nodes, flags);
1317 }
1318 
1319 /* Set the process memory policy */
1320 SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
1321                 unsigned long, maxnode)
1322 {
1323         int err;
1324         nodemask_t nodes;
1325         unsigned short flags;
1326 
1327         flags = mode & MPOL_MODE_FLAGS;
1328         mode &= ~MPOL_MODE_FLAGS;
1329         if ((unsigned int)mode >= MPOL_MAX)
1330                 return -EINVAL;
1331         if ((flags & MPOL_F_STATIC_NODES) && (flags & MPOL_F_RELATIVE_NODES))
1332                 return -EINVAL;
1333         err = get_nodes(&nodes, nmask, maxnode);
1334         if (err)
1335                 return err;
1336         return do_set_mempolicy(mode, flags, &nodes);
1337 }
1338 
1339 SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
1340                 const unsigned long __user *, old_nodes,
1341                 const unsigned long __user *, new_nodes)
1342 {
1343         const struct cred *cred = current_cred(), *tcred;
1344         struct mm_struct *mm = NULL;
1345         struct task_struct *task;
1346         nodemask_t task_nodes;
1347         int err;
1348         nodemask_t *old;
1349         nodemask_t *new;
1350         NODEMASK_SCRATCH(scratch);
1351 
1352         if (!scratch)
1353                 return -ENOMEM;
1354 
1355         old = &scratch->mask1;
1356         new = &scratch->mask2;
1357 
1358         err = get_nodes(old, old_nodes, maxnode);
1359         if (err)
1360                 goto out;
1361 
1362         err = get_nodes(new, new_nodes, maxnode);
1363         if (err)
1364                 goto out;
1365 
1366         /* Find the mm_struct */
1367         rcu_read_lock();
1368         task = pid ? find_task_by_vpid(pid) : current;
1369         if (!task) {
1370                 rcu_read_unlock();
1371                 err = -ESRCH;
1372                 goto out;
1373         }
1374         get_task_struct(task);
1375 
1376         err = -EINVAL;
1377 
1378         /*
1379          * Check if this process has the right to modify the specified
1380          * process. The right exists if the process has administrative
1381          * capabilities, superuser privileges or the same
1382          * userid as the target process.
1383          */
1384         tcred = __task_cred(task);
1385         if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) &&
1386             !uid_eq(cred->uid,  tcred->suid) && !uid_eq(cred->uid,  tcred->uid) &&
1387             !capable(CAP_SYS_NICE)) {
1388                 rcu_read_unlock();
1389                 err = -EPERM;
1390                 goto out_put;
1391         }
1392         rcu_read_unlock();
1393 
1394         task_nodes = cpuset_mems_allowed(task);
1395         /* Is the user allowed to access the target nodes? */
1396         if (!nodes_subset(*new, task_nodes) && !capable(CAP_SYS_NICE)) {
1397                 err = -EPERM;
1398                 goto out_put;
1399         }
1400 
1401         if (!nodes_subset(*new, node_states[N_MEMORY])) {
1402                 err = -EINVAL;
1403                 goto out_put;
1404         }
1405 
1406         err = security_task_movememory(task);
1407         if (err)
1408                 goto out_put;
1409 
1410         mm = get_task_mm(task);
1411         put_task_struct(task);
1412 
1413         if (!mm) {
1414                 err = -EINVAL;
1415                 goto out;
1416         }
1417 
1418         err = do_migrate_pages(mm, old, new,
1419                 capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
1420 
1421         mmput(mm);
1422 out:
1423         NODEMASK_SCRATCH_FREE(scratch);
1424 
1425         return err;
1426 
1427 out_put:
1428         put_task_struct(task);
1429         goto out;
1430 
1431 }
1432 
1433 
1434 /* Retrieve NUMA policy */
1435 SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
1436                 unsigned long __user *, nmask, unsigned long, maxnode,
1437                 unsigned long, addr, unsigned long, flags)
1438 {
1439         int err;
1440         int uninitialized_var(pval);
1441         nodemask_t nodes;
1442 
1443         if (nmask != NULL && maxnode < MAX_NUMNODES)
1444                 return -EINVAL;
1445 
1446         err = do_get_mempolicy(&pval, &nodes, addr, flags);
1447 
1448         if (err)
1449                 return err;
1450 
1451         if (policy && put_user(pval, policy))
1452                 return -EFAULT;
1453 
1454         if (nmask)
1455                 err = copy_nodes_to_user(nmask, maxnode, &nodes);
1456 
1457         return err;
1458 }
1459 
1460 #ifdef CONFIG_COMPAT
1461 
1462 COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
1463                        compat_ulong_t __user *, nmask,
1464                        compat_ulong_t, maxnode,
1465                        compat_ulong_t, addr, compat_ulong_t, flags)
1466 {
1467         long err;
1468         unsigned long __user *nm = NULL;
1469         unsigned long nr_bits, alloc_size;
1470         DECLARE_BITMAP(bm, MAX_NUMNODES);
1471 
1472         nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
1473         alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1474 
1475         if (nmask)
1476                 nm = compat_alloc_user_space(alloc_size);
1477 
1478         err = sys_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
1479 
1480         if (!err && nmask) {
1481                 unsigned long copy_size;
1482                 copy_size = min_t(unsigned long, sizeof(bm), alloc_size);
1483                 err = copy_from_user(bm, nm, copy_size);
1484                 /* ensure entire bitmap is zeroed */
1485                 err |= clear_user(nmask, ALIGN(maxnode-1, 8) / 8);
1486                 err |= compat_put_bitmap(nmask, bm, nr_bits);
1487         }
1488 
1489         return err;
1490 }
1491 
1492 COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,
1493                        compat_ulong_t, maxnode)
1494 {
1495         long err = 0;
1496         unsigned long __user *nm = NULL;
1497         unsigned long nr_bits, alloc_size;
1498         DECLARE_BITMAP(bm, MAX_NUMNODES);
1499 
1500         nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
1501         alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1502 
1503         if (nmask) {
1504                 err = compat_get_bitmap(bm, nmask, nr_bits);
1505                 nm = compat_alloc_user_space(alloc_size);
1506                 err |= copy_to_user(nm, bm, alloc_size);
1507         }
1508 
1509         if (err)
1510                 return -EFAULT;
1511 
1512         return sys_set_mempolicy(mode, nm, nr_bits+1);
1513 }
1514 
1515 COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
1516                        compat_ulong_t, mode, compat_ulong_t __user *, nmask,
1517                        compat_ulong_t, maxnode, compat_ulong_t, flags)
1518 {
1519         long err = 0;
1520         unsigned long __user *nm = NULL;
1521         unsigned long nr_bits, alloc_size;
1522         nodemask_t bm;
1523 
1524         nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
1525         alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1526 
1527         if (nmask) {
1528                 err = compat_get_bitmap(nodes_addr(bm), nmask, nr_bits);
1529                 nm = compat_alloc_user_space(alloc_size);
1530                 err |= copy_to_user(nm, nodes_addr(bm), alloc_size);
1531         }
1532 
1533         if (err)
1534                 return -EFAULT;
1535 
1536         return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
1537 }
1538 
1539 #endif
1540 
1541 struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,
1542                                                 unsigned long addr)
1543 {
1544         struct mempolicy *pol = NULL;
1545 
1546         if (vma) {
1547                 if (vma->vm_ops && vma->vm_ops->get_policy) {
1548                         pol = vma->vm_ops->get_policy(vma, addr);
1549                 } else if (vma->vm_policy) {
1550                         pol = vma->vm_policy;
1551 
1552                         /*
1553                          * shmem_alloc_page() passes MPOL_F_SHARED policy with
1554                          * a pseudo vma whose vma->vm_ops=NULL. Take a reference
1555                          * count on these policies which will be dropped by
1556                          * mpol_cond_put() later
1557                          */
1558                         if (mpol_needs_cond_ref(pol))
1559                                 mpol_get(pol);
1560                 }
1561         }
1562 
1563         return pol;
1564 }
1565 
1566 /*
1567  * get_vma_policy(@vma, @addr)
1568  * @vma: virtual memory area whose policy is sought
1569  * @addr: address in @vma for shared policy lookup
1570  *
1571  * Returns effective policy for a VMA at specified address.
1572  * Falls back to current->mempolicy or system default policy, as necessary.
1573  * Shared policies [those marked as MPOL_F_SHARED] require an extra reference
1574  * count--added by the get_policy() vm_op, as appropriate--to protect against
1575  * freeing by another task.  It is the caller's responsibility to free the
1576  * extra reference for shared policies.
1577  */
1578 static struct mempolicy *get_vma_policy(struct vm_area_struct *vma,
1579                                                 unsigned long addr)
1580 {
1581         struct mempolicy *pol = __get_vma_policy(vma, addr);
1582 
1583         if (!pol)
1584                 pol = get_task_policy(current);
1585 
1586         return pol;
1587 }
1588 
1589 bool vma_policy_mof(struct vm_area_struct *vma)
1590 {
1591         struct mempolicy *pol;
1592 
1593         if (vma->vm_ops && vma->vm_ops->get_policy) {
1594                 bool ret = false;
1595 
1596                 pol = vma->vm_ops->get_policy(vma, vma->vm_start);
1597                 if (pol && (pol->flags & MPOL_F_MOF))
1598                         ret = true;
1599                 mpol_cond_put(pol);
1600 
1601                 return ret;
1602         }
1603 
1604         pol = vma->vm_policy;
1605         if (!pol)
1606                 pol = get_task_policy(current);
1607 
1608         return pol->flags & MPOL_F_MOF;
1609 }
1610 
1611 static int apply_policy_zone(struct mempolicy *policy, enum zone_type zone)
1612 {
1613         enum zone_type dynamic_policy_zone = policy_zone;
1614 
1615         BUG_ON(dynamic_policy_zone == ZONE_MOVABLE);
1616 
1617         /*
1618          * if policy->v.nodes has movable memory only,
1619          * we apply policy when gfp_zone(gfp) = ZONE_MOVABLE only.
1620          *
1621          * policy->v.nodes is intersect with node_states[N_MEMORY].
1622          * so if the following test faile, it implies
1623          * policy->v.nodes has movable memory only.
1624          */
1625         if (!nodes_intersects(policy->v.nodes, node_states[N_HIGH_MEMORY]))
1626                 dynamic_policy_zone = ZONE_MOVABLE;
1627 
1628         return zone >= dynamic_policy_zone;
1629 }
1630 
1631 /*
1632  * Return a nodemask representing a mempolicy for filtering nodes for
1633  * page allocation
1634  */
1635 static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
1636 {
1637         /* Lower zones don't get a nodemask applied for MPOL_BIND */
1638         if (unlikely(policy->mode == MPOL_BIND) &&
1639                         apply_policy_zone(policy, gfp_zone(gfp)) &&
1640                         cpuset_nodemask_valid_mems_allowed(&policy->v.nodes))
1641                 return &policy->v.nodes;
1642 
1643         return NULL;
1644 }
1645 
1646 /* Return a zonelist indicated by gfp for node representing a mempolicy */
1647 static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy,
1648         int nd)
1649 {
1650         switch (policy->mode) {
1651         case MPOL_PREFERRED:
1652                 if (!(policy->flags & MPOL_F_LOCAL))
1653                         nd = policy->v.preferred_node;
1654                 break;
1655         case MPOL_BIND:
1656                 /*
1657                  * Normally, MPOL_BIND allocations are node-local within the
1658                  * allowed nodemask.  However, if __GFP_THISNODE is set and the
1659                  * current node isn't part of the mask, we use the zonelist for
1660                  * the first node in the mask instead.
1661                  */
1662                 if (unlikely(gfp & __GFP_THISNODE) &&
1663                                 unlikely(!node_isset(nd, policy->v.nodes)))
1664                         nd = first_node(policy->v.nodes);
1665                 break;
1666         default:
1667                 BUG();
1668         }
1669         return node_zonelist(nd, gfp);
1670 }
1671 
1672 /* Do dynamic interleaving for a process */
1673 static unsigned interleave_nodes(struct mempolicy *policy)
1674 {
1675         unsigned nid, next;
1676         struct task_struct *me = current;
1677 
1678         nid = me->il_next;
1679         next = next_node(nid, policy->v.nodes);
1680         if (next >= MAX_NUMNODES)
1681                 next = first_node(policy->v.nodes);
1682         if (next < MAX_NUMNODES)
1683                 me->il_next = next;
1684         return nid;
1685 }
1686 
1687 /*
1688  * Depending on the memory policy provide a node from which to allocate the
1689  * next slab entry.
1690  */
1691 unsigned int mempolicy_slab_node(void)
1692 {
1693         struct mempolicy *policy;
1694         int node = numa_mem_id();
1695 
1696         if (in_interrupt())
1697                 return node;
1698 
1699         policy = current->mempolicy;
1700         if (!policy || policy->flags & MPOL_F_LOCAL)
1701                 return node;
1702 
1703         switch (policy->mode) {
1704         case MPOL_PREFERRED:
1705                 /*
1706                  * handled MPOL_F_LOCAL above
1707                  */
1708                 return policy->v.preferred_node;
1709 
1710         case MPOL_INTERLEAVE:
1711                 return interleave_nodes(policy);
1712 
1713         case MPOL_BIND: {
1714                 /*
1715                  * Follow bind policy behavior and start allocation at the
1716                  * first node.
1717                  */
1718                 struct zonelist *zonelist;
1719                 struct zone *zone;
1720                 enum zone_type highest_zoneidx = gfp_zone(GFP_KERNEL);
1721                 zonelist = &NODE_DATA(node)->node_zonelists[0];
1722                 (void)first_zones_zonelist(zonelist, highest_zoneidx,
1723                                                         &policy->v.nodes,
1724                                                         &zone);
1725                 return zone ? zone->node : node;
1726         }
1727 
1728         default:
1729                 BUG();
1730         }
1731 }
1732 
1733 /* Do static interleaving for a VMA with known offset. */
1734 static unsigned offset_il_node(struct mempolicy *pol,
1735                 struct vm_area_struct *vma, unsigned long off)
1736 {
1737         unsigned nnodes = nodes_weight(pol->v.nodes);
1738         unsigned target;
1739         int c;
1740         int nid = NUMA_NO_NODE;
1741 
1742         if (!nnodes)
1743                 return numa_node_id();
1744         target = (unsigned int)off % nnodes;
1745         c = 0;
1746         do {
1747                 nid = next_node(nid, pol->v.nodes);
1748                 c++;
1749         } while (c <= target);
1750         return nid;
1751 }
1752 
1753 /* Determine a node number for interleave */
1754 static inline unsigned interleave_nid(struct mempolicy *pol,
1755                  struct vm_area_struct *vma, unsigned long addr, int shift)
1756 {
1757         if (vma) {
1758                 unsigned long off;
1759 
1760                 /*
1761                  * for small pages, there is no difference between
1762                  * shift and PAGE_SHIFT, so the bit-shift is safe.
1763                  * for huge pages, since vm_pgoff is in units of small
1764                  * pages, we need to shift off the always 0 bits to get
1765                  * a useful offset.
1766                  */
1767                 BUG_ON(shift < PAGE_SHIFT);
1768                 off = vma->vm_pgoff >> (shift - PAGE_SHIFT);
1769                 off += (addr - vma->vm_start) >> shift;
1770                 return offset_il_node(pol, vma, off);
1771         } else
1772                 return interleave_nodes(pol);
1773 }
1774 
1775 /*
1776  * Return the bit number of a random bit set in the nodemask.
1777  * (returns NUMA_NO_NODE if nodemask is empty)
1778  */
1779 int node_random(const nodemask_t *maskp)
1780 {
1781         int w, bit = NUMA_NO_NODE;
1782 
1783         w = nodes_weight(*maskp);
1784         if (w)
1785                 bit = bitmap_ord_to_pos(maskp->bits,
1786                         get_random_int() % w, MAX_NUMNODES);
1787         return bit;
1788 }
1789 
1790 #ifdef CONFIG_HUGETLBFS
1791 /*
1792  * huge_zonelist(@vma, @addr, @gfp_flags, @mpol)
1793  * @vma: virtual memory area whose policy is sought
1794  * @addr: address in @vma for shared policy lookup and interleave policy
1795  * @gfp_flags: for requested zone
1796  * @mpol: pointer to mempolicy pointer for reference counted mempolicy
1797  * @nodemask: pointer to nodemask pointer for MPOL_BIND nodemask
1798  *
1799  * Returns a zonelist suitable for a huge page allocation and a pointer
1800  * to the struct mempolicy for conditional unref after allocation.
1801  * If the effective policy is 'BIND, returns a pointer to the mempolicy's
1802  * @nodemask for filtering the zonelist.
1803  *
1804  * Must be protected by read_mems_allowed_begin()
1805  */
1806 struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
1807                                 gfp_t gfp_flags, struct mempolicy **mpol,
1808                                 nodemask_t **nodemask)
1809 {
1810         struct zonelist *zl;
1811 
1812         *mpol = get_vma_policy(vma, addr);
1813         *nodemask = NULL;       /* assume !MPOL_BIND */
1814 
1815         if (unlikely((*mpol)->mode == MPOL_INTERLEAVE)) {
1816                 zl = node_zonelist(interleave_nid(*mpol, vma, addr,
1817                                 huge_page_shift(hstate_vma(vma))), gfp_flags);
1818         } else {
1819                 zl = policy_zonelist(gfp_flags, *mpol, numa_node_id());
1820                 if ((*mpol)->mode == MPOL_BIND)
1821                         *nodemask = &(*mpol)->v.nodes;
1822         }
1823         return zl;
1824 }
1825 
1826 /*
1827  * init_nodemask_of_mempolicy
1828  *
1829  * If the current task's mempolicy is "default" [NULL], return 'false'
1830  * to indicate default policy.  Otherwise, extract the policy nodemask
1831  * for 'bind' or 'interleave' policy into the argument nodemask, or
1832  * initialize the argument nodemask to contain the single node for
1833  * 'preferred' or 'local' policy and return 'true' to indicate presence
1834  * of non-default mempolicy.
1835  *
1836  * We don't bother with reference counting the mempolicy [mpol_get/put]
1837  * because the current task is examining it's own mempolicy and a task's
1838  * mempolicy is only ever changed by the task itself.
1839  *
1840  * N.B., it is the caller's responsibility to free a returned nodemask.
1841  */
1842 bool init_nodemask_of_mempolicy(nodemask_t *mask)
1843 {
1844         struct mempolicy *mempolicy;
1845         int nid;
1846 
1847         if (!(mask && current->mempolicy))
1848                 return false;
1849 
1850         task_lock(current);
1851         mempolicy = current->mempolicy;
1852         switch (mempolicy->mode) {
1853         case MPOL_PREFERRED:
1854                 if (mempolicy->flags & MPOL_F_LOCAL)
1855                         nid = numa_node_id();
1856                 else
1857                         nid = mempolicy->v.preferred_node;
1858                 init_nodemask_of_node(mask, nid);
1859                 break;
1860 
1861         case MPOL_BIND:
1862                 /* Fall through */
1863         case MPOL_INTERLEAVE:
1864                 *mask =  mempolicy->v.nodes;
1865                 break;
1866 
1867         default:
1868                 BUG();
1869         }
1870         task_unlock(current);
1871 
1872         return true;
1873 }
1874 #endif
1875 
1876 /*
1877  * mempolicy_nodemask_intersects
1878  *
1879  * If tsk's mempolicy is "default" [NULL], return 'true' to indicate default
1880  * policy.  Otherwise, check for intersection between mask and the policy
1881  * nodemask for 'bind' or 'interleave' policy.  For 'perferred' or 'local'
1882  * policy, always return true since it may allocate elsewhere on fallback.
1883  *
1884  * Takes task_lock(tsk) to prevent freeing of its mempolicy.
1885  */
1886 bool mempolicy_nodemask_intersects(struct task_struct *tsk,
1887                                         const nodemask_t *mask)
1888 {
1889         struct mempolicy *mempolicy;
1890         bool ret = true;
1891 
1892         if (!mask)
1893                 return ret;
1894         task_lock(tsk);
1895         mempolicy = tsk->mempolicy;
1896         if (!mempolicy)
1897                 goto out;
1898 
1899         switch (mempolicy->mode) {
1900         case MPOL_PREFERRED:
1901                 /*
1902                  * MPOL_PREFERRED and MPOL_F_LOCAL are only preferred nodes to
1903                  * allocate from, they may fallback to other nodes when oom.
1904                  * Thus, it's possible for tsk to have allocated memory from
1905                  * nodes in mask.
1906                  */
1907                 break;
1908         case MPOL_BIND:
1909         case MPOL_INTERLEAVE:
1910                 ret = nodes_intersects(mempolicy->v.nodes, *mask);
1911                 break;
1912         default:
1913                 BUG();
1914         }
1915 out:
1916         task_unlock(tsk);
1917         return ret;
1918 }
1919 
1920 /* Allocate a page in interleaved policy.
1921    Own path because it needs to do special accounting. */
1922 static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
1923                                         unsigned nid)
1924 {
1925         struct zonelist *zl;
1926         struct page *page;
1927 
1928         zl = node_zonelist(nid, gfp);
1929         page = __alloc_pages(gfp, order, zl);
1930         if (page && page_zone(page) == zonelist_zone(&zl->_zonerefs[0]))
1931                 inc_zone_page_state(page, NUMA_INTERLEAVE_HIT);
1932         return page;
1933 }
1934 
1935 /**
1936  *      alloc_pages_vma - Allocate a page for a VMA.
1937  *
1938  *      @gfp:
1939  *      %GFP_USER    user allocation.
1940  *      %GFP_KERNEL  kernel allocations,
1941  *      %GFP_HIGHMEM highmem/user allocations,
1942  *      %GFP_FS      allocation should not call back into a file system.
1943  *      %GFP_ATOMIC  don't sleep.
1944  *
1945  *      @order:Order of the GFP allocation.
1946  *      @vma:  Pointer to VMA or NULL if not available.
1947  *      @addr: Virtual Address of the allocation. Must be inside the VMA.
1948  *      @node: Which node to prefer for allocation (modulo policy).
1949  *      @hugepage: for hugepages try only the preferred node if possible
1950  *
1951  *      This function allocates a page from the kernel page pool and applies
1952  *      a NUMA policy associated with the VMA or the current process.
1953  *      When VMA is not NULL caller must hold down_read on the mmap_sem of the
1954  *      mm_struct of the VMA to prevent it from going away. Should be used for
1955  *      all allocations for pages that will be mapped into user space. Returns
1956  *      NULL when no page can be allocated.
1957  */
1958 struct page *
1959 alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
1960                 unsigned long addr, int node, bool hugepage)
1961 {
1962         struct mempolicy *pol;
1963         struct page *page;
1964         unsigned int cpuset_mems_cookie;
1965         struct zonelist *zl;
1966         nodemask_t *nmask;
1967 
1968 retry_cpuset:
1969         pol = get_vma_policy(vma, addr);
1970         cpuset_mems_cookie = read_mems_allowed_begin();
1971 
1972         if (pol->mode == MPOL_INTERLEAVE) {
1973                 unsigned nid;
1974 
1975                 nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
1976                 mpol_cond_put(pol);
1977                 page = alloc_page_interleave(gfp, order, nid);
1978                 goto out;
1979         }
1980 
1981         if (unlikely(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hugepage)) {
1982                 int hpage_node = node;
1983 
1984                 /*
1985                  * For hugepage allocation and non-interleave policy which
1986                  * allows the current node (or other explicitly preferred
1987                  * node) we only try to allocate from the current/preferred
1988                  * node and don't fall back to other nodes, as the cost of
1989                  * remote accesses would likely offset THP benefits.
1990                  *
1991                  * If the policy is interleave, or does not allow the current
1992                  * node in its nodemask, we allocate the standard way.
1993                  */
1994                 if (pol->mode == MPOL_PREFERRED &&
1995                                                 !(pol->flags & MPOL_F_LOCAL))
1996                         hpage_node = pol->v.preferred_node;
1997 
1998                 nmask = policy_nodemask(gfp, pol);
1999                 if (!nmask || node_isset(hpage_node, *nmask)) {
2000                         mpol_cond_put(pol);
2001                         page = __alloc_pages_node(hpage_node,
2002                                                 gfp | __GFP_THISNODE, order);
2003                         goto out;
2004                 }
2005         }
2006 
2007         nmask = policy_nodemask(gfp, pol);
2008         zl = policy_zonelist(gfp, pol, node);
2009         mpol_cond_put(pol);
2010         page = __alloc_pages_nodemask(gfp, order, zl, nmask);
2011 out:
2012         if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
2013                 goto retry_cpuset;
2014         return page;
2015 }
2016 
2017 /**
2018  *      alloc_pages_current - Allocate pages.
2019  *
2020  *      @gfp:
2021  *              %GFP_USER   user allocation,
2022  *              %GFP_KERNEL kernel allocation,
2023  *              %GFP_HIGHMEM highmem allocation,
2024  *              %GFP_FS     don't call back into a file system.
2025  *              %GFP_ATOMIC don't sleep.
2026  *      @order: Power of two of allocation size in pages. 0 is a single page.
2027  *
2028  *      Allocate a page from the kernel page pool.  When not in
2029  *      interrupt context and apply the current process NUMA policy.
2030  *      Returns NULL when no page can be allocated.
2031  *
2032  *      Don't call cpuset_update_task_memory_state() unless
2033  *      1) it's ok to take cpuset_sem (can WAIT), and
2034  *      2) allocating for current task (not interrupt).
2035  */
2036 struct page *alloc_pages_current(gfp_t gfp, unsigned order)
2037 {
2038         struct mempolicy *pol = &default_policy;
2039         struct page *page;
2040         unsigned int cpuset_mems_cookie;
2041 
2042         if (!in_interrupt() && !(gfp & __GFP_THISNODE))
2043                 pol = get_task_policy(current);
2044 
2045 retry_cpuset:
2046         cpuset_mems_cookie = read_mems_allowed_begin();
2047 
2048         /*
2049          * No reference counting needed for current->mempolicy
2050          * nor system default_policy
2051          */
2052         if (pol->mode == MPOL_INTERLEAVE)
2053                 page = alloc_page_interleave(gfp, order, interleave_nodes(pol));
2054         else
2055                 page = __alloc_pages_nodemask(gfp, order,
2056                                 policy_zonelist(gfp, pol, numa_node_id()),
2057                                 policy_nodemask(gfp, pol));
2058 
2059         if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
2060                 goto retry_cpuset;
2061 
2062         return page;
2063 }
2064 EXPORT_SYMBOL(alloc_pages_current);
2065 
2066 int vma_dup_policy(struct vm_area_struct *src, struct vm_area_struct *dst)
2067 {
2068         struct mempolicy *pol = mpol_dup(vma_policy(src));
2069 
2070         if (IS_ERR(pol))
2071                 return PTR_ERR(pol);
2072         dst->vm_policy = pol;
2073         return 0;
2074 }
2075 
2076 /*
2077  * If mpol_dup() sees current->cpuset == cpuset_being_rebound, then it
2078  * rebinds the mempolicy its copying by calling mpol_rebind_policy()
2079  * with the mems_allowed returned by cpuset_mems_allowed().  This
2080  * keeps mempolicies cpuset relative after its cpuset moves.  See
2081  * further kernel/cpuset.c update_nodemask().
2082  *
2083  * current's mempolicy may be rebinded by the other task(the task that changes
2084  * cpuset's mems), so we needn't do rebind work for current task.
2085  */
2086 
2087 /* Slow path of a mempolicy duplicate */
2088 struct mempolicy *__mpol_dup(struct mempolicy *old)
2089 {
2090         struct mempolicy *new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
2091 
2092         if (!new)
2093                 return ERR_PTR(-ENOMEM);
2094 
2095         /* task's mempolicy is protected by alloc_lock */
2096         if (old == current->mempolicy) {
2097                 task_lock(current);
2098                 *new = *old;
2099                 task_unlock(current);
2100         } else
2101                 *new = *old;
2102 
2103         if (current_cpuset_is_being_rebound()) {
2104                 nodemask_t mems = cpuset_mems_allowed(current);
2105                 if (new->flags & MPOL_F_REBINDING)
2106                         mpol_rebind_policy(new, &mems, MPOL_REBIND_STEP2);
2107                 else
2108                         mpol_rebind_policy(new, &mems, MPOL_REBIND_ONCE);
2109         }
2110         atomic_set(&new->refcnt, 1);
2111         return new;
2112 }
2113 
2114 /* Slow path of a mempolicy comparison */
2115 bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
2116 {
2117         if (!a || !b)
2118                 return false;
2119         if (a->mode != b->mode)
2120                 return false;
2121         if (a->flags != b->flags)
2122                 return false;
2123         if (mpol_store_user_nodemask(a))
2124                 if (!nodes_equal(a->w.user_nodemask, b->w.user_nodemask))
2125                         return false;
2126 
2127         switch (a->mode) {
2128         case MPOL_BIND:
2129                 /* Fall through */
2130         case MPOL_INTERLEAVE:
2131                 return !!nodes_equal(a->v.nodes, b->v.nodes);
2132         case MPOL_PREFERRED:
2133                 return a->v.preferred_node == b->v.preferred_node;
2134         default:
2135                 BUG();
2136                 return false;
2137         }
2138 }
2139 
2140 /*
2141  * Shared memory backing store policy support.
2142  *
2143  * Remember policies even when nobody has shared memory mapped.
2144  * The policies are kept in Red-Black tree linked from the inode.
2145  * They are protected by the sp->lock spinlock, which should be held
2146  * for any accesses to the tree.
2147  */
2148 
2149 /* lookup first element intersecting start-end */
2150 /* Caller holds sp->lock */
2151 static struct sp_node *
2152 sp_lookup(struct shared_policy *sp, unsigned long start, unsigned long end)
2153 {
2154         struct rb_node *n = sp->root.rb_node;
2155 
2156         while (n) {
2157                 struct sp_node *p = rb_entry(n, struct sp_node, nd);
2158 
2159                 if (start >= p->end)
2160                         n = n->rb_right;
2161                 else if (end <= p->start)
2162                         n = n->rb_left;
2163                 else
2164                         break;
2165         }
2166         if (!n)
2167                 return NULL;
2168         for (;;) {
2169                 struct sp_node *w = NULL;
2170                 struct rb_node *prev = rb_prev(n);
2171                 if (!prev)
2172                         break;
2173                 w = rb_entry(prev, struct sp_node, nd);
2174                 if (w->end <= start)
2175                         break;
2176                 n = prev;
2177         }
2178         return rb_entry(n, struct sp_node, nd);
2179 }
2180 
2181 /* Insert a new shared policy into the list. */
2182 /* Caller holds sp->lock */
2183 static void sp_insert(struct shared_policy *sp, struct sp_node *new)
2184 {
2185         struct rb_node **p = &sp->root.rb_node;
2186         struct rb_node *parent = NULL;
2187         struct sp_node *nd;
2188 
2189         while (*p) {
2190                 parent = *p;
2191                 nd = rb_entry(parent, struct sp_node, nd);
2192                 if (new->start < nd->start)
2193                         p = &(*p)->rb_left;
2194                 else if (new->end > nd->end)
2195                         p = &(*p)->rb_right;
2196                 else
2197                         BUG();
2198         }
2199         rb_link_node(&new->nd, parent, p);
2200         rb_insert_color(&new->nd, &sp->root);
2201         pr_debug("inserting %lx-%lx: %d\n", new->start, new->end,
2202                  new->policy ? new->policy->mode : 0);
2203 }
2204 
2205 /* Find shared policy intersecting idx */
2206 struct mempolicy *
2207 mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)
2208 {
2209         struct mempolicy *pol = NULL;
2210         struct sp_node *sn;
2211 
2212         if (!sp->root.rb_node)
2213                 return NULL;
2214         spin_lock(&sp->lock);
2215         sn = sp_lookup(sp, idx, idx+1);
2216         if (sn) {
2217                 mpol_get(sn->policy);
2218                 pol = sn->policy;
2219         }
2220         spin_unlock(&sp->lock);
2221         return pol;
2222 }
2223 
2224 static void sp_free(struct sp_node *n)
2225 {
2226         mpol_put(n->policy);
2227         kmem_cache_free(sn_cache, n);
2228 }
2229 
2230 /**
2231  * mpol_misplaced - check whether current page node is valid in policy
2232  *
2233  * @page: page to be checked
2234  * @vma: vm area where page mapped
2235  * @addr: virtual address where page mapped
2236  *
2237  * Lookup current policy node id for vma,addr and "compare to" page's
2238  * node id.
2239  *
2240  * Returns:
2241  *      -1      - not misplaced, page is in the right node
2242  *      node    - node id where the page should be
2243  *
2244  * Policy determination "mimics" alloc_page_vma().
2245  * Called from fault path where we know the vma and faulting address.
2246  */
2247 int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long addr)
2248 {
2249         struct mempolicy *pol;
2250         struct zone *zone;
2251         int curnid = page_to_nid(page);
2252         unsigned long pgoff;
2253         int thiscpu = raw_smp_processor_id();
2254         int thisnid = cpu_to_node(thiscpu);
2255         int polnid = -1;
2256         int ret = -1;
2257 
2258         BUG_ON(!vma);
2259 
2260         pol = get_vma_policy(vma, addr);
2261         if (!(pol->flags & MPOL_F_MOF))
2262                 goto out;
2263 
2264         switch (pol->mode) {
2265         case MPOL_INTERLEAVE:
2266                 BUG_ON(addr >= vma->vm_end);
2267                 BUG_ON(addr < vma->vm_start);
2268 
2269                 pgoff = vma->vm_pgoff;
2270                 pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;
2271                 polnid = offset_il_node(pol, vma, pgoff);
2272                 break;
2273 
2274         case MPOL_PREFERRED:
2275                 if (pol->flags & MPOL_F_LOCAL)
2276                         polnid = numa_node_id();
2277                 else
2278                         polnid = pol->v.preferred_node;
2279                 break;
2280 
2281         case MPOL_BIND:
2282                 /*
2283                  * allows binding to multiple nodes.
2284                  * use current page if in policy nodemask,
2285                  * else select nearest allowed node, if any.
2286                  * If no allowed nodes, use current [!misplaced].
2287                  */
2288                 if (node_isset(curnid, pol->v.nodes))
2289                         goto out;
2290                 (void)first_zones_zonelist(
2291                                 node_zonelist(numa_node_id(), GFP_HIGHUSER),
2292                                 gfp_zone(GFP_HIGHUSER),
2293                                 &pol->v.nodes, &zone);
2294                 polnid = zone->node;
2295                 break;
2296 
2297         default:
2298                 BUG();
2299         }
2300 
2301         /* Migrate the page towards the node whose CPU is referencing it */
2302         if (pol->flags & MPOL_F_MORON) {
2303                 polnid = thisnid;
2304 
2305                 if (!should_numa_migrate_memory(current, page, curnid, thiscpu))
2306                         goto out;
2307         }
2308 
2309         if (curnid != polnid)
2310                 ret = polnid;
2311 out:
2312         mpol_cond_put(pol);
2313 
2314         return ret;
2315 }
2316 
2317 static void sp_delete(struct shared_policy *sp, struct sp_node *n)
2318 {
2319         pr_debug("deleting %lx-l%lx\n", n->start, n->end);
2320         rb_erase(&n->nd, &sp->root);
2321         sp_free(n);
2322 }
2323 
2324 static void sp_node_init(struct sp_node *node, unsigned long start,
2325                         unsigned long end, struct mempolicy *pol)
2326 {
2327         node->start = start;
2328         node->end = end;
2329         node->policy = pol;
2330 }
2331 
2332 static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
2333                                 struct mempolicy *pol)
2334 {
2335         struct sp_node *n;
2336         struct mempolicy *newpol;
2337 
2338         n = kmem_cache_alloc(sn_cache, GFP_KERNEL);
2339         if (!n)
2340                 return NULL;
2341 
2342         newpol = mpol_dup(pol);
2343         if (IS_ERR(newpol)) {
2344                 kmem_cache_free(sn_cache, n);
2345                 return NULL;
2346         }
2347         newpol->flags |= MPOL_F_SHARED;
2348         sp_node_init(n, start, end, newpol);
2349 
2350         return n;
2351 }
2352 
2353 /* Replace a policy range. */
2354 static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
2355                                  unsigned long end, struct sp_node *new)
2356 {
2357         struct sp_node *n;
2358         struct sp_node *n_new = NULL;
2359         struct mempolicy *mpol_new = NULL;
2360         int ret = 0;
2361 
2362 restart:
2363         spin_lock(&sp->lock);
2364         n = sp_lookup(sp, start, end);
2365         /* Take care of old policies in the same range. */
2366         while (n && n->start < end) {
2367                 struct rb_node *next = rb_next(&n->nd);
2368                 if (n->start >= start) {
2369                         if (n->end <= end)
2370                                 sp_delete(sp, n);
2371                         else
2372                                 n->start = end;
2373                 } else {
2374                         /* Old policy spanning whole new range. */
2375                         if (n->end > end) {
2376                                 if (!n_new)
2377                                         goto alloc_new;
2378 
2379                                 *mpol_new = *n->policy;
2380                                 atomic_set(&mpol_new->refcnt, 1);
2381                                 sp_node_init(n_new, end, n->end, mpol_new);
2382                                 n->end = start;
2383                                 sp_insert(sp, n_new);
2384                                 n_new = NULL;
2385                                 mpol_new = NULL;
2386                                 break;
2387                         } else
2388                                 n->end = start;
2389                 }
2390                 if (!next)
2391                         break;
2392                 n = rb_entry(next, struct sp_node, nd);
2393         }
2394         if (new)
2395                 sp_insert(sp, new);
2396         spin_unlock(&sp->lock);
2397         ret = 0;
2398 
2399 err_out:
2400         if (mpol_new)
2401                 mpol_put(mpol_new);
2402         if (n_new)
2403                 kmem_cache_free(sn_cache, n_new);
2404 
2405         return ret;
2406 
2407 alloc_new:
2408         spin_unlock(&sp->lock);
2409         ret = -ENOMEM;
2410         n_new = kmem_cache_alloc(sn_cache, GFP_KERNEL);
2411         if (!n_new)
2412                 goto err_out;
2413         mpol_new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
2414         if (!mpol_new)
2415                 goto err_out;
2416         goto restart;
2417 }
2418 
2419 /**
2420  * mpol_shared_policy_init - initialize shared policy for inode
2421  * @sp: pointer to inode shared policy
2422  * @mpol:  struct mempolicy to install
2423  *
2424  * Install non-NULL @mpol in inode's shared policy rb-tree.
2425  * On entry, the current task has a reference on a non-NULL @mpol.
2426  * This must be released on exit.
2427  * This is called at get_inode() calls and we can use GFP_KERNEL.
2428  */
2429 void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
2430 {
2431         int ret;
2432 
2433         sp->root = RB_ROOT;             /* empty tree == default mempolicy */
2434         spin_lock_init(&sp->lock);
2435 
2436         if (mpol) {
2437                 struct vm_area_struct pvma;
2438                 struct mempolicy *new;
2439                 NODEMASK_SCRATCH(scratch);
2440 
2441                 if (!scratch)
2442                         goto put_mpol;
2443                 /* contextualize the tmpfs mount point mempolicy */
2444                 new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
2445                 if (IS_ERR(new))
2446                         goto free_scratch; /* no valid nodemask intersection */
2447 
2448                 task_lock(current);
2449                 ret = mpol_set_nodemask(new, &mpol->w.user_nodemask, scratch);
2450                 task_unlock(current);
2451                 if (ret)
2452                         goto put_new;
2453 
2454                 /* Create pseudo-vma that contains just the policy */
2455                 memset(&pvma, 0, sizeof(struct vm_area_struct));
2456                 pvma.vm_end = TASK_SIZE;        /* policy covers entire file */
2457                 mpol_set_shared_policy(sp, &pvma, new); /* adds ref */
2458 
2459 put_new:
2460                 mpol_put(new);                  /* drop initial ref */
2461 free_scratch:
2462                 NODEMASK_SCRATCH_FREE(scratch);
2463 put_mpol:
2464                 mpol_put(mpol); /* drop our incoming ref on sb mpol */
2465         }
2466 }
2467 
2468 int mpol_set_shared_policy(struct shared_policy *info,
2469                         struct vm_area_struct *vma, struct mempolicy *npol)
2470 {
2471         int err;
2472         struct sp_node *new = NULL;
2473         unsigned long sz = vma_pages(vma);
2474 
2475         pr_debug("set_shared_policy %lx sz %lu %d %d %lx\n",
2476                  vma->vm_pgoff,
2477                  sz, npol ? npol->mode : -1,
2478                  npol ? npol->flags : -1,
2479                  npol ? nodes_addr(npol->v.nodes)[0] : NUMA_NO_NODE);
2480 
2481         if (npol) {
2482                 new = sp_alloc(vma->vm_pgoff, vma->vm_pgoff + sz, npol);
2483                 if (!new)
2484                         return -ENOMEM;
2485         }
2486         err = shared_policy_replace(info, vma->vm_pgoff, vma->vm_pgoff+sz, new);
2487         if (err && new)
2488                 sp_free(new);
2489         return err;
2490 }
2491 
2492 /* Free a backing policy store on inode delete. */
2493 void mpol_free_shared_policy(struct shared_policy *p)
2494 {
2495         struct sp_node *n;
2496         struct rb_node *next;
2497 
2498         if (!p->root.rb_node)
2499                 return;
2500         spin_lock(&p->lock);
2501         next = rb_first(&p->root);
2502         while (next) {
2503                 n = rb_entry(next, struct sp_node, nd);
2504                 next = rb_next(&n->nd);
2505                 sp_delete(p, n);
2506         }
2507         spin_unlock(&p->lock);
2508 }
2509 
2510 #ifdef CONFIG_NUMA_BALANCING
2511 static int __initdata numabalancing_override;
2512 
2513 static void __init check_numabalancing_enable(void)
2514 {
2515         bool numabalancing_default = false;
2516 
2517         if (IS_ENABLED(CONFIG_NUMA_BALANCING_DEFAULT_ENABLED))
2518                 numabalancing_default = true;
2519 
2520         /* Parsed by setup_numabalancing. override == 1 enables, -1 disables */
2521         if (numabalancing_override)
2522                 set_numabalancing_state(numabalancing_override == 1);
2523 
2524         if (num_online_nodes() > 1 && !numabalancing_override) {
2525                 pr_info("%s automatic NUMA balancing. "
2526                         "Configure with numa_balancing= or the "
2527                         "kernel.numa_balancing sysctl",
2528                         numabalancing_default ? "Enabling" : "Disabling");
2529                 set_numabalancing_state(numabalancing_default);
2530         }
2531 }
2532 
2533 static int __init setup_numabalancing(char *str)
2534 {
2535         int ret = 0;
2536         if (!str)
2537                 goto out;
2538 
2539         if (!strcmp(str, "enable")) {
2540                 numabalancing_override = 1;
2541                 ret = 1;
2542         } else if (!strcmp(str, "disable")) {
2543                 numabalancing_override = -1;
2544                 ret = 1;
2545         }
2546 out:
2547         if (!ret)
2548                 pr_warn("Unable to parse numa_balancing=\n");
2549 
2550         return ret;
2551 }
2552 __setup("numa_balancing=", setup_numabalancing);
2553 #else
2554 static inline void __init check_numabalancing_enable(void)
2555 {
2556 }
2557 #endif /* CONFIG_NUMA_BALANCING */
2558 
2559 /* assumes fs == KERNEL_DS */
2560 void __init numa_policy_init(void)
2561 {
2562         nodemask_t interleave_nodes;
2563         unsigned long largest = 0;
2564         int nid, prefer = 0;
2565 
2566         policy_cache = kmem_cache_create("numa_policy",
2567                                          sizeof(struct mempolicy),
2568                                          0, SLAB_PANIC, NULL);
2569 
2570         sn_cache = kmem_cache_create("shared_policy_node",
2571                                      sizeof(struct sp_node),
2572                                      0, SLAB_PANIC, NULL);
2573 
2574         for_each_node(nid) {
2575                 preferred_node_policy[nid] = (struct mempolicy) {
2576                         .refcnt = ATOMIC_INIT(1),
2577                         .mode = MPOL_PREFERRED,
2578                         .flags = MPOL_F_MOF | MPOL_F_MORON,
2579                         .v = { .preferred_node = nid, },
2580                 };
2581         }
2582 
2583         /*
2584          * Set interleaving policy for system init. Interleaving is only
2585          * enabled across suitably sized nodes (default is >= 16MB), or
2586          * fall back to the largest node if they're all smaller.
2587          */
2588         nodes_clear(interleave_nodes);
2589         for_each_node_state(nid, N_MEMORY) {
2590                 unsigned long total_pages = node_present_pages(nid);
2591 
2592                 /* Preserve the largest node */
2593                 if (largest < total_pages) {
2594                         largest = total_pages;
2595                         prefer = nid;
2596                 }
2597 
2598                 /* Interleave this node? */
2599                 if ((total_pages << PAGE_SHIFT) >= (16 << 20))
2600                         node_set(nid, interleave_nodes);
2601         }
2602 
2603         /* All too small, use the largest */
2604         if (unlikely(nodes_empty(interleave_nodes)))
2605                 node_set(prefer, interleave_nodes);
2606 
2607         if (do_set_mempolicy(MPOL_INTERLEAVE, 0, &interleave_nodes))
2608                 pr_err("%s: interleaving failed\n", __func__);
2609 
2610         check_numabalancing_enable();
2611 }
2612 
2613 /* Reset policy of current process to default */
2614 void numa_default_policy(void)
2615 {
2616         do_set_mempolicy(MPOL_DEFAULT, 0, NULL);
2617 }
2618 
2619 /*
2620  * Parse and format mempolicy from/to strings
2621  */
2622 
2623 /*
2624  * "local" is implemented internally by MPOL_PREFERRED with MPOL_F_LOCAL flag.
2625  */
2626 static const char * const policy_modes[] =
2627 {
2628         [MPOL_DEFAULT]    = "default",
2629         [MPOL_PREFERRED]  = "prefer",
2630         [MPOL_BIND]       = "bind",
2631         [MPOL_INTERLEAVE] = "interleave",
2632         [MPOL_LOCAL]      = "local",
2633 };
2634 
2635 
2636 #ifdef CONFIG_TMPFS
2637 /**
2638  * mpol_parse_str - parse string to mempolicy, for tmpfs mpol mount option.
2639  * @str:  string containing mempolicy to parse
2640  * @mpol:  pointer to struct mempolicy pointer, returned on success.
2641  *
2642  * Format of input:
2643  *      <mode>[=<flags>][:<nodelist>]
2644  *
2645  * On success, returns 0, else 1
2646  */
2647 int mpol_parse_str(char *str, struct mempolicy **mpol)
2648 {
2649         struct mempolicy *new = NULL;
2650         unsigned short mode;
2651         unsigned short mode_flags;
2652         nodemask_t nodes;
2653         char *nodelist = strchr(str, ':');
2654         char *flags = strchr(str, '=');
2655         int err = 1;
2656 
2657         if (nodelist) {
2658                 /* NUL-terminate mode or flags string */
2659                 *nodelist++ = '\0';
2660                 if (nodelist_parse(nodelist, nodes))
2661                         goto out;
2662                 if (!nodes_subset(nodes, node_states[N_MEMORY]))
2663                         goto out;
2664         } else
2665                 nodes_clear(nodes);
2666 
2667         if (flags)
2668                 *flags++ = '\0';        /* terminate mode string */
2669 
2670         for (mode = 0; mode < MPOL_MAX; mode++) {
2671                 if (!strcmp(str, policy_modes[mode])) {
2672                         break;
2673                 }
2674         }
2675         if (mode >= MPOL_MAX)
2676                 goto out;
2677 
2678         switch (mode) {
2679         case MPOL_PREFERRED:
2680                 /*
2681                  * Insist on a nodelist of one node only
2682                  */
2683                 if (nodelist) {
2684                         char *rest = nodelist;
2685                         while (isdigit(*rest))
2686                                 rest++;
2687                         if (*rest)
2688                                 goto out;
2689                 }
2690                 break;
2691         case MPOL_INTERLEAVE:
2692                 /*
2693                  * Default to online nodes with memory if no nodelist
2694                  */
2695                 if (!nodelist)
2696                         nodes = node_states[N_MEMORY];
2697                 break;
2698         case MPOL_LOCAL:
2699                 /*
2700                  * Don't allow a nodelist;  mpol_new() checks flags
2701                  */
2702                 if (nodelist)
2703                         goto out;
2704                 mode = MPOL_PREFERRED;
2705                 break;
2706         case MPOL_DEFAULT:
2707                 /*
2708                  * Insist on a empty nodelist
2709                  */
2710                 if (!nodelist)
2711                         err = 0;
2712                 goto out;
2713         case MPOL_BIND:
2714                 /*
2715                  * Insist on a nodelist
2716                  */
2717                 if (!nodelist)
2718                         goto out;
2719         }
2720 
2721         mode_flags = 0;
2722         if (flags) {
2723                 /*
2724                  * Currently, we only support two mutually exclusive
2725                  * mode flags.
2726                  */
2727                 if (!strcmp(flags, "static"))
2728                         mode_flags |= MPOL_F_STATIC_NODES;
2729                 else if (!strcmp(flags, "relative"))
2730                         mode_flags |= MPOL_F_RELATIVE_NODES;
2731                 else
2732                         goto out;
2733         }
2734 
2735         new = mpol_new(mode, mode_flags, &nodes);
2736         if (IS_ERR(new))
2737                 goto out;
2738 
2739         /*
2740          * Save nodes for mpol_to_str() to show the tmpfs mount options
2741          * for /proc/mounts, /proc/pid/mounts and /proc/pid/mountinfo.
2742          */
2743         if (mode != MPOL_PREFERRED)
2744                 new->v.nodes = nodes;
2745         else if (nodelist)
2746                 new->v.preferred_node = first_node(nodes);
2747         else
2748                 new->flags |= MPOL_F_LOCAL;
2749 
2750         /*
2751          * Save nodes for contextualization: this will be used to "clone"
2752          * the mempolicy in a specific context [cpuset] at a later time.
2753          */
2754         new->w.user_nodemask = nodes;
2755 
2756         err = 0;
2757 
2758 out:
2759         /* Restore string for error message */
2760         if (nodelist)
2761                 *--nodelist = ':';
2762         if (flags)
2763                 *--flags = '=';
2764         if (!err)
2765                 *mpol = new;
2766         return err;
2767 }
2768 #endif /* CONFIG_TMPFS */
2769 
2770 /**
2771  * mpol_to_str - format a mempolicy structure for printing
2772  * @buffer:  to contain formatted mempolicy string
2773  * @maxlen:  length of @buffer
2774  * @pol:  pointer to mempolicy to be formatted
2775  *
2776  * Convert @pol into a string.  If @buffer is too short, truncate the string.
2777  * Recommend a @maxlen of at least 32 for the longest mode, "interleave", the
2778  * longest flag, "relative", and to display at least a few node ids.
2779  */
2780 void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
2781 {
2782         char *p = buffer;
2783         nodemask_t nodes = NODE_MASK_NONE;
2784         unsigned short mode = MPOL_DEFAULT;
2785         unsigned short flags = 0;
2786 
2787         if (pol && pol != &default_policy && !(pol->flags & MPOL_F_MORON)) {
2788                 mode = pol->mode;
2789                 flags = pol->flags;
2790         }
2791 
2792         switch (mode) {
2793         case MPOL_DEFAULT:
2794                 break;
2795         case MPOL_PREFERRED:
2796                 if (flags & MPOL_F_LOCAL)
2797                         mode = MPOL_LOCAL;
2798                 else
2799                         node_set(pol->v.preferred_node, nodes);
2800                 break;
2801         case MPOL_BIND:
2802         case MPOL_INTERLEAVE:
2803                 nodes = pol->v.nodes;
2804                 break;
2805         default:
2806                 WARN_ON_ONCE(1);
2807                 snprintf(p, maxlen, "unknown");
2808                 return;
2809         }
2810 
2811         p += snprintf(p, maxlen, "%s", policy_modes[mode]);
2812 
2813         if (flags & MPOL_MODE_FLAGS) {
2814                 p += snprintf(p, buffer + maxlen - p, "=");
2815 
2816                 /*
2817                  * Currently, the only defined flags are mutually exclusive
2818                  */
2819                 if (flags & MPOL_F_STATIC_NODES)
2820                         p += snprintf(p, buffer + maxlen - p, "static");
2821                 else if (flags & MPOL_F_RELATIVE_NODES)
2822                         p += snprintf(p, buffer + maxlen - p, "relative");
2823         }
2824 
2825         if (!nodes_empty(nodes))
2826                 p += scnprintf(p, buffer + maxlen - p, ":%*pbl",
2827                                nodemask_pr_args(&nodes));
2828 }
2829 

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