root/mm/mempolicy.c

DEFINITIONS

1. get_task_policy
2. mpol_store_user_nodemask
3. mpol_relative_nodemask
4. mpol_new_interleave
5. mpol_new_preferred
6. mpol_new_bind
7. mpol_set_nodemask
8. mpol_new
9. __mpol_put
10. mpol_rebind_default
11. mpol_rebind_nodemask
12. mpol_rebind_preferred
13. mpol_rebind_policy
14. mpol_rebind_task
15. mpol_rebind_mm
16. queue_pages_required
17. queue_pages_pmd
18. queue_pages_pte_range
19. queue_pages_hugetlb
20. change_prot_numa
21. change_prot_numa
22. queue_pages_test_walk
23. queue_pages_range
24. vma_replace_policy
25. mbind_range
26. do_set_mempolicy
27. get_policy_nodemask
28. lookup_node
29. do_get_mempolicy
30. migrate_page_add
31. alloc_new_node_page
32. migrate_to_node
33. do_migrate_pages
34. new_page
35. migrate_page_add
36. do_migrate_pages
37. new_page
38. do_mbind
39. get_nodes
40. copy_nodes_to_user
41. kernel_mbind
42. SYSCALL_DEFINE6
43. kernel_set_mempolicy
44. SYSCALL_DEFINE3
45. kernel_migrate_pages
46. SYSCALL_DEFINE4
47. kernel_get_mempolicy
48. SYSCALL_DEFINE5
49. COMPAT_SYSCALL_DEFINE5
50. COMPAT_SYSCALL_DEFINE3
51. COMPAT_SYSCALL_DEFINE6
52. COMPAT_SYSCALL_DEFINE4
53. __get_vma_policy
54. get_vma_policy
55. vma_policy_mof
56. apply_policy_zone
57. policy_nodemask
58. policy_node
59. interleave_nodes
60. mempolicy_slab_node
61. offset_il_node
62. interleave_nid
63. huge_node
64. init_nodemask_of_mempolicy
65. mempolicy_nodemask_intersects
66. alloc_page_interleave
67. alloc_pages_vma
68. alloc_pages_current
69. vma_dup_policy
70. __mpol_dup
71. __mpol_equal
72. sp_lookup
73. sp_insert
74. mpol_shared_policy_lookup
75. sp_free
76. mpol_misplaced
77. mpol_put_task_policy
78. sp_delete
79. sp_node_init
80. sp_alloc
81. shared_policy_replace
82. mpol_shared_policy_init
83. mpol_set_shared_policy
84. mpol_free_shared_policy
85. check_numabalancing_enable
86. setup_numabalancing
87. check_numabalancing_enable
88. numa_policy_init
89. numa_default_policy
90. mpol_parse_str
91. mpol_to_str

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Simple NUMA memory policy for the Linux kernel.
   4  *
   5  * Copyright 2003,2004 Andi Kleen, SuSE Labs.
   6  * (C) Copyright 2005 Christoph Lameter, Silicon Graphics, Inc.
   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/pagewalk.h>
  72 #include <linux/highmem.h>
  73 #include <linux/hugetlb.h>
  74 #include <linux/kernel.h>
  75 #include <linux/sched.h>
  76 #include <linux/sched/mm.h>
  77 #include <linux/sched/numa_balancing.h>
  78 #include <linux/sched/task.h>
  79 #include <linux/nodemask.h>
  80 #include <linux/cpuset.h>
  81 #include <linux/slab.h>
  82 #include <linux/string.h>
  83 #include <linux/export.h>
  84 #include <linux/nsproxy.h>
  85 #include <linux/interrupt.h>
  86 #include <linux/init.h>
  87 #include <linux/compat.h>
  88 #include <linux/ptrace.h>
  89 #include <linux/swap.h>
  90 #include <linux/seq_file.h>
  91 #include <linux/proc_fs.h>
  92 #include <linux/migrate.h>
  93 #include <linux/ksm.h>
  94 #include <linux/rmap.h>
  95 #include <linux/security.h>
  96 #include <linux/syscalls.h>
  97 #include <linux/ctype.h>
  98 #include <linux/mm_inline.h>
  99 #include <linux/mmu_notifier.h>
 100 #include <linux/printk.h>
 101 #include <linux/swapops.h>
 102 
 103 #include <asm/tlbflush.h>
 104 #include <linux/uaccess.h>
 105 
 106 #include "internal.h"
 107 
 108 /* Internal flags */
 109 #define MPOL_MF_DISCONTIG_OK (MPOL_MF_INTERNAL << 0)    /* Skip checks for continuous vmas */
 110 #define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1)          /* Invert check for nodemask */
 111 
 112 static struct kmem_cache *policy_cache;
 113 static struct kmem_cache *sn_cache;
 114 
 115 /* Highest zone. An specific allocation for a zone below that is not
 116    policied. */
 117 enum zone_type policy_zone = 0;
 118 
 119 /*
 120  * run-time system-wide default policy => local allocation
 121  */
 122 static struct mempolicy default_policy = {
 123         .refcnt = ATOMIC_INIT(1), /* never free it */
 124         .mode = MPOL_PREFERRED,
 125         .flags = MPOL_F_LOCAL,
 126 };
 127 
 128 static struct mempolicy preferred_node_policy[MAX_NUMNODES];
 129 
 130 struct mempolicy *get_task_policy(struct task_struct *p)
 131 {
 132         struct mempolicy *pol = p->mempolicy;
 133         int node;
 134 
 135         if (pol)
 136                 return pol;
 137 
 138         node = numa_node_id();
 139         if (node != NUMA_NO_NODE) {
 140                 pol = &preferred_node_policy[node];
 141                 /* preferred_node_policy is not initialised early in boot */
 142                 if (pol->mode)
 143                         return pol;
 144         }
 145 
 146         return &default_policy;
 147 }
 148 
 149 static const struct mempolicy_operations {
 150         int (*create)(struct mempolicy *pol, const nodemask_t *nodes);
 151         void (*rebind)(struct mempolicy *pol, const nodemask_t *nodes);
 152 } mpol_ops[MPOL_MAX];
 153 
 154 static inline int mpol_store_user_nodemask(const struct mempolicy *pol)
 155 {
 156         return pol->flags & MPOL_MODE_FLAGS;
 157 }
 158 
 159 static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,
 160                                    const nodemask_t *rel)
 161 {
 162         nodemask_t tmp;
 163         nodes_fold(tmp, *orig, nodes_weight(*rel));
 164         nodes_onto(*ret, tmp, *rel);
 165 }
 166 
 167 static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes)
 168 {
 169         if (nodes_empty(*nodes))
 170                 return -EINVAL;
 171         pol->v.nodes = *nodes;
 172         return 0;
 173 }
 174 
 175 static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes)
 176 {
 177         if (!nodes)
 178                 pol->flags |= MPOL_F_LOCAL;     /* local allocation */
 179         else if (nodes_empty(*nodes))
 180                 return -EINVAL;                 /*  no allowed nodes */
 181         else
 182                 pol->v.preferred_node = first_node(*nodes);
 183         return 0;
 184 }
 185 
 186 static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
 187 {
 188         if (nodes_empty(*nodes))
 189                 return -EINVAL;
 190         pol->v.nodes = *nodes;
 191         return 0;
 192 }
 193 
 194 /*
 195  * mpol_set_nodemask is called after mpol_new() to set up the nodemask, if
 196  * any, for the new policy.  mpol_new() has already validated the nodes
 197  * parameter with respect to the policy mode and flags.  But, we need to
 198  * handle an empty nodemask with MPOL_PREFERRED here.
 199  *
 200  * Must be called holding task's alloc_lock to protect task's mems_allowed
 201  * and mempolicy.  May also be called holding the mmap_semaphore for write.
 202  */
 203 static int mpol_set_nodemask(struct mempolicy *pol,
 204                      const nodemask_t *nodes, struct nodemask_scratch *nsc)
 205 {
 206         int ret;
 207 
 208         /* if mode is MPOL_DEFAULT, pol is NULL. This is right. */
 209         if (pol == NULL)
 210                 return 0;
 211         /* Check N_MEMORY */
 212         nodes_and(nsc->mask1,
 213                   cpuset_current_mems_allowed, node_states[N_MEMORY]);
 214 
 215         VM_BUG_ON(!nodes);
 216         if (pol->mode == MPOL_PREFERRED && nodes_empty(*nodes))
 217                 nodes = NULL;   /* explicit local allocation */
 218         else {
 219                 if (pol->flags & MPOL_F_RELATIVE_NODES)
 220                         mpol_relative_nodemask(&nsc->mask2, nodes, &nsc->mask1);
 221                 else
 222                         nodes_and(nsc->mask2, *nodes, nsc->mask1);
 223 
 224                 if (mpol_store_user_nodemask(pol))
 225                         pol->w.user_nodemask = *nodes;
 226                 else
 227                         pol->w.cpuset_mems_allowed =
 228                                                 cpuset_current_mems_allowed;
 229         }
 230 
 231         if (nodes)
 232                 ret = mpol_ops[pol->mode].create(pol, &nsc->mask2);
 233         else
 234                 ret = mpol_ops[pol->mode].create(pol, NULL);
 235         return ret;
 236 }
 237 
 238 /*
 239  * This function just creates a new policy, does some check and simple
 240  * initialization. You must invoke mpol_set_nodemask() to set nodes.
 241  */
 242 static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
 243                                   nodemask_t *nodes)
 244 {
 245         struct mempolicy *policy;
 246 
 247         pr_debug("setting mode %d flags %d nodes[0] %lx\n",
 248                  mode, flags, nodes ? nodes_addr(*nodes)[0] : NUMA_NO_NODE);
 249 
 250         if (mode == MPOL_DEFAULT) {
 251                 if (nodes && !nodes_empty(*nodes))
 252                         return ERR_PTR(-EINVAL);
 253                 return NULL;
 254         }
 255         VM_BUG_ON(!nodes);
 256 
 257         /*
 258          * MPOL_PREFERRED cannot be used with MPOL_F_STATIC_NODES or
 259          * MPOL_F_RELATIVE_NODES if the nodemask is empty (local allocation).
 260          * All other modes require a valid pointer to a non-empty nodemask.
 261          */
 262         if (mode == MPOL_PREFERRED) {
 263                 if (nodes_empty(*nodes)) {
 264                         if (((flags & MPOL_F_STATIC_NODES) ||
 265                              (flags & MPOL_F_RELATIVE_NODES)))
 266                                 return ERR_PTR(-EINVAL);
 267                 }
 268         } else if (mode == MPOL_LOCAL) {
 269                 if (!nodes_empty(*nodes) ||
 270                     (flags & MPOL_F_STATIC_NODES) ||
 271                     (flags & MPOL_F_RELATIVE_NODES))
 272                         return ERR_PTR(-EINVAL);
 273                 mode = MPOL_PREFERRED;
 274         } else if (nodes_empty(*nodes))
 275                 return ERR_PTR(-EINVAL);
 276         policy = kmem_cache_alloc(policy_cache, GFP_KERNEL);
 277         if (!policy)
 278                 return ERR_PTR(-ENOMEM);
 279         atomic_set(&policy->refcnt, 1);
 280         policy->mode = mode;
 281         policy->flags = flags;
 282 
 283         return policy;
 284 }
 285 
 286 /* Slow path of a mpol destructor. */
 287 void __mpol_put(struct mempolicy *p)
 288 {
 289         if (!atomic_dec_and_test(&p->refcnt))
 290                 return;
 291         kmem_cache_free(policy_cache, p);
 292 }
 293 
 294 static void mpol_rebind_default(struct mempolicy *pol, const nodemask_t *nodes)
 295 {
 296 }
 297 
 298 static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes)
 299 {
 300         nodemask_t tmp;
 301 
 302         if (pol->flags & MPOL_F_STATIC_NODES)
 303                 nodes_and(tmp, pol->w.user_nodemask, *nodes);
 304         else if (pol->flags & MPOL_F_RELATIVE_NODES)
 305                 mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
 306         else {
 307                 nodes_remap(tmp, pol->v.nodes,pol->w.cpuset_mems_allowed,
 308                                                                 *nodes);
 309                 pol->w.cpuset_mems_allowed = *nodes;
 310         }
 311 
 312         if (nodes_empty(tmp))
 313                 tmp = *nodes;
 314 
 315         pol->v.nodes = tmp;
 316 }
 317 
 318 static void mpol_rebind_preferred(struct mempolicy *pol,
 319                                                 const nodemask_t *nodes)
 320 {
 321         nodemask_t tmp;
 322 
 323         if (pol->flags & MPOL_F_STATIC_NODES) {
 324                 int node = first_node(pol->w.user_nodemask);
 325 
 326                 if (node_isset(node, *nodes)) {
 327                         pol->v.preferred_node = node;
 328                         pol->flags &= ~MPOL_F_LOCAL;
 329                 } else
 330                         pol->flags |= MPOL_F_LOCAL;
 331         } else if (pol->flags & MPOL_F_RELATIVE_NODES) {
 332                 mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
 333                 pol->v.preferred_node = first_node(tmp);
 334         } else if (!(pol->flags & MPOL_F_LOCAL)) {
 335                 pol->v.preferred_node = node_remap(pol->v.preferred_node,
 336                                                    pol->w.cpuset_mems_allowed,
 337                                                    *nodes);
 338                 pol->w.cpuset_mems_allowed = *nodes;
 339         }
 340 }
 341 
 342 /*
 343  * mpol_rebind_policy - Migrate a policy to a different set of nodes
 344  *
 345  * Per-vma policies are protected by mmap_sem. Allocations using per-task
 346  * policies are protected by task->mems_allowed_seq to prevent a premature
 347  * OOM/allocation failure due to parallel nodemask modification.
 348  */
 349 static void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *newmask)
 350 {
 351         if (!pol)
 352                 return;
 353         if (!mpol_store_user_nodemask(pol) && !(pol->flags & MPOL_F_LOCAL) &&
 354             nodes_equal(pol->w.cpuset_mems_allowed, *newmask))
 355                 return;
 356 
 357         mpol_ops[pol->mode].rebind(pol, newmask);
 358 }
 359 
 360 /*
 361  * Wrapper for mpol_rebind_policy() that just requires task
 362  * pointer, and updates task mempolicy.
 363  *
 364  * Called with task's alloc_lock held.
 365  */
 366 
 367 void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new)
 368 {
 369         mpol_rebind_policy(tsk->mempolicy, new);
 370 }
 371 
 372 /*
 373  * Rebind each vma in mm to new nodemask.
 374  *
 375  * Call holding a reference to mm.  Takes mm->mmap_sem during call.
 376  */
 377 
 378 void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
 379 {
 380         struct vm_area_struct *vma;
 381 
 382         down_write(&mm->mmap_sem);
 383         for (vma = mm->mmap; vma; vma = vma->vm_next)
 384                 mpol_rebind_policy(vma->vm_policy, new);
 385         up_write(&mm->mmap_sem);
 386 }
 387 
 388 static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
 389         [MPOL_DEFAULT] = {
 390                 .rebind = mpol_rebind_default,
 391         },
 392         [MPOL_INTERLEAVE] = {
 393                 .create = mpol_new_interleave,
 394                 .rebind = mpol_rebind_nodemask,
 395         },
 396         [MPOL_PREFERRED] = {
 397                 .create = mpol_new_preferred,
 398                 .rebind = mpol_rebind_preferred,
 399         },
 400         [MPOL_BIND] = {
 401                 .create = mpol_new_bind,
 402                 .rebind = mpol_rebind_nodemask,
 403         },
 404 };
 405 
 406 static int migrate_page_add(struct page *page, struct list_head *pagelist,
 407                                 unsigned long flags);
 408 
 409 struct queue_pages {
 410         struct list_head *pagelist;
 411         unsigned long flags;
 412         nodemask_t *nmask;
 413         struct vm_area_struct *prev;
 414 };
 415 
 416 /*
 417  * Check if the page's nid is in qp->nmask.
 418  *
 419  * If MPOL_MF_INVERT is set in qp->flags, check if the nid is
 420  * in the invert of qp->nmask.
 421  */
 422 static inline bool queue_pages_required(struct page *page,
 423                                         struct queue_pages *qp)
 424 {
 425         int nid = page_to_nid(page);
 426         unsigned long flags = qp->flags;
 427 
 428         return node_isset(nid, *qp->nmask) == !(flags & MPOL_MF_INVERT);
 429 }
 430 
 431 /*
 432  * queue_pages_pmd() has four possible return values:
 433  * 0 - pages are placed on the right node or queued successfully.
 434  * 1 - there is unmovable page, and MPOL_MF_MOVE* & MPOL_MF_STRICT were
 435  *     specified.
 436  * 2 - THP was split.
 437  * -EIO - is migration entry or only MPOL_MF_STRICT was specified and an
 438  *        existing page was already on a node that does not follow the
 439  *        policy.
 440  */
 441 static int queue_pages_pmd(pmd_t *pmd, spinlock_t *ptl, unsigned long addr,
 442                                 unsigned long end, struct mm_walk *walk)
 443 {
 444         int ret = 0;
 445         struct page *page;
 446         struct queue_pages *qp = walk->private;
 447         unsigned long flags;
 448 
 449         if (unlikely(is_pmd_migration_entry(*pmd))) {
 450                 ret = -EIO;
 451                 goto unlock;
 452         }
 453         page = pmd_page(*pmd);
 454         if (is_huge_zero_page(page)) {
 455                 spin_unlock(ptl);
 456                 __split_huge_pmd(walk->vma, pmd, addr, false, NULL);
 457                 ret = 2;
 458                 goto out;
 459         }
 460         if (!queue_pages_required(page, qp))
 461                 goto unlock;
 462 
 463         flags = qp->flags;
 464         /* go to thp migration */
 465         if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
 466                 if (!vma_migratable(walk->vma) ||
 467                     migrate_page_add(page, qp->pagelist, flags)) {
 468                         ret = 1;
 469                         goto unlock;
 470                 }
 471         } else
 472                 ret = -EIO;
 473 unlock:
 474         spin_unlock(ptl);
 475 out:
 476         return ret;
 477 }
 478 
 479 /*
 480  * Scan through pages checking if pages follow certain conditions,
 481  * and move them to the pagelist if they do.
 482  *
 483  * queue_pages_pte_range() has three possible return values:
 484  * 0 - pages are placed on the right node or queued successfully.
 485  * 1 - there is unmovable page, and MPOL_MF_MOVE* & MPOL_MF_STRICT were
 486  *     specified.
 487  * -EIO - only MPOL_MF_STRICT was specified and an existing page was already
 488  *        on a node that does not follow the policy.
 489  */
 490 static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
 491                         unsigned long end, struct mm_walk *walk)
 492 {
 493         struct vm_area_struct *vma = walk->vma;
 494         struct page *page;
 495         struct queue_pages *qp = walk->private;
 496         unsigned long flags = qp->flags;
 497         int ret;
 498         bool has_unmovable = false;
 499         pte_t *pte;
 500         spinlock_t *ptl;
 501 
 502         ptl = pmd_trans_huge_lock(pmd, vma);
 503         if (ptl) {
 504                 ret = queue_pages_pmd(pmd, ptl, addr, end, walk);
 505                 if (ret != 2)
 506                         return ret;
 507         }
 508         /* THP was split, fall through to pte walk */
 509 
 510         if (pmd_trans_unstable(pmd))
 511                 return 0;
 512 
 513         pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
 514         for (; addr != end; pte++, addr += PAGE_SIZE) {
 515                 if (!pte_present(*pte))
 516                         continue;
 517                 page = vm_normal_page(vma, addr, *pte);
 518                 if (!page)
 519                         continue;
 520                 /*
 521                  * vm_normal_page() filters out zero pages, but there might
 522                  * still be PageReserved pages to skip, perhaps in a VDSO.
 523                  */
 524                 if (PageReserved(page))
 525                         continue;
 526                 if (!queue_pages_required(page, qp))
 527                         continue;
 528                 if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
 529                         /* MPOL_MF_STRICT must be specified if we get here */
 530                         if (!vma_migratable(vma)) {
 531                                 has_unmovable = true;
 532                                 break;
 533                         }
 534 
 535                         /*
 536                          * Do not abort immediately since there may be
 537                          * temporary off LRU pages in the range.  Still
 538                          * need migrate other LRU pages.
 539                          */
 540                         if (migrate_page_add(page, qp->pagelist, flags))
 541                                 has_unmovable = true;
 542                 } else
 543                         break;
 544         }
 545         pte_unmap_unlock(pte - 1, ptl);
 546         cond_resched();
 547 
 548         if (has_unmovable)
 549                 return 1;
 550 
 551         return addr != end ? -EIO : 0;
 552 }
 553 
 554 static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
 555                                unsigned long addr, unsigned long end,
 556                                struct mm_walk *walk)
 557 {
 558 #ifdef CONFIG_HUGETLB_PAGE
 559         struct queue_pages *qp = walk->private;
 560         unsigned long flags = qp->flags;
 561         struct page *page;
 562         spinlock_t *ptl;
 563         pte_t entry;
 564 
 565         ptl = huge_pte_lock(hstate_vma(walk->vma), walk->mm, pte);
 566         entry = huge_ptep_get(pte);
 567         if (!pte_present(entry))
 568                 goto unlock;
 569         page = pte_page(entry);
 570         if (!queue_pages_required(page, qp))
 571                 goto unlock;
 572         /* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
 573         if (flags & (MPOL_MF_MOVE_ALL) ||
 574             (flags & MPOL_MF_MOVE && page_mapcount(page) == 1))
 575                 isolate_huge_page(page, qp->pagelist);
 576 unlock:
 577         spin_unlock(ptl);
 578 #else
 579         BUG();
 580 #endif
 581         return 0;
 582 }
 583 
 584 #ifdef CONFIG_NUMA_BALANCING
 585 /*
 586  * This is used to mark a range of virtual addresses to be inaccessible.
 587  * These are later cleared by a NUMA hinting fault. Depending on these
 588  * faults, pages may be migrated for better NUMA placement.
 589  *
 590  * This is assuming that NUMA faults are handled using PROT_NONE. If
 591  * an architecture makes a different choice, it will need further
 592  * changes to the core.
 593  */
 594 unsigned long change_prot_numa(struct vm_area_struct *vma,
 595                         unsigned long addr, unsigned long end)
 596 {
 597         int nr_updated;
 598 
 599         nr_updated = change_protection(vma, addr, end, PAGE_NONE, 0, 1);
 600         if (nr_updated)
 601                 count_vm_numa_events(NUMA_PTE_UPDATES, nr_updated);
 602 
 603         return nr_updated;
 604 }
 605 #else
 606 static unsigned long change_prot_numa(struct vm_area_struct *vma,
 607                         unsigned long addr, unsigned long end)
 608 {
 609         return 0;
 610 }
 611 #endif /* CONFIG_NUMA_BALANCING */
 612 
 613 static int queue_pages_test_walk(unsigned long start, unsigned long end,
 614                                 struct mm_walk *walk)
 615 {
 616         struct vm_area_struct *vma = walk->vma;
 617         struct queue_pages *qp = walk->private;
 618         unsigned long endvma = vma->vm_end;
 619         unsigned long flags = qp->flags;
 620 
 621         /*
 622          * Need check MPOL_MF_STRICT to return -EIO if possible
 623          * regardless of vma_migratable
 624          */
 625         if (!vma_migratable(vma) &&
 626             !(flags & MPOL_MF_STRICT))
 627                 return 1;
 628 
 629         if (endvma > end)
 630                 endvma = end;
 631         if (vma->vm_start > start)
 632                 start = vma->vm_start;
 633 
 634         if (!(flags & MPOL_MF_DISCONTIG_OK)) {
 635                 if (!vma->vm_next && vma->vm_end < end)
 636                         return -EFAULT;
 637                 if (qp->prev && qp->prev->vm_end < vma->vm_start)
 638                         return -EFAULT;
 639         }
 640 
 641         qp->prev = vma;
 642 
 643         if (flags & MPOL_MF_LAZY) {
 644                 /* Similar to task_numa_work, skip inaccessible VMAs */
 645                 if (!is_vm_hugetlb_page(vma) &&
 646                         (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) &&
 647                         !(vma->vm_flags & VM_MIXEDMAP))
 648                         change_prot_numa(vma, start, endvma);
 649                 return 1;
 650         }
 651 
 652         /* queue pages from current vma */
 653         if (flags & MPOL_MF_VALID)
 654                 return 0;
 655         return 1;
 656 }
 657 
 658 static const struct mm_walk_ops queue_pages_walk_ops = {
 659         .hugetlb_entry          = queue_pages_hugetlb,
 660         .pmd_entry              = queue_pages_pte_range,
 661         .test_walk              = queue_pages_test_walk,
 662 };
 663 
 664 /*
 665  * Walk through page tables and collect pages to be migrated.
 666  *
 667  * If pages found in a given range are on a set of nodes (determined by
 668  * @nodes and @flags,) it's isolated and queued to the pagelist which is
 669  * passed via @private.
 670  *
 671  * queue_pages_range() has three possible return values:
 672  * 1 - there is unmovable page, but MPOL_MF_MOVE* & MPOL_MF_STRICT were
 673  *     specified.
 674  * 0 - queue pages successfully or no misplaced page.
 675  * errno - i.e. misplaced pages with MPOL_MF_STRICT specified (-EIO) or
 676  *         memory range specified by nodemask and maxnode points outside
 677  *         your accessible address space (-EFAULT)
 678  */
 679 static int
 680 queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
 681                 nodemask_t *nodes, unsigned long flags,
 682                 struct list_head *pagelist)
 683 {
 684         struct queue_pages qp = {
 685                 .pagelist = pagelist,
 686                 .flags = flags,
 687                 .nmask = nodes,
 688                 .prev = NULL,
 689         };
 690 
 691         return walk_page_range(mm, start, end, &queue_pages_walk_ops, &qp);
 692 }
 693 
 694 /*
 695  * Apply policy to a single VMA
 696  * This must be called with the mmap_sem held for writing.
 697  */
 698 static int vma_replace_policy(struct vm_area_struct *vma,
 699                                                 struct mempolicy *pol)
 700 {
 701         int err;
 702         struct mempolicy *old;
 703         struct mempolicy *new;
 704 
 705         pr_debug("vma %lx-%lx/%lx vm_ops %p vm_file %p set_policy %p\n",
 706                  vma->vm_start, vma->vm_end, vma->vm_pgoff,
 707                  vma->vm_ops, vma->vm_file,
 708                  vma->vm_ops ? vma->vm_ops->set_policy : NULL);
 709 
 710         new = mpol_dup(pol);
 711         if (IS_ERR(new))
 712                 return PTR_ERR(new);
 713 
 714         if (vma->vm_ops && vma->vm_ops->set_policy) {
 715                 err = vma->vm_ops->set_policy(vma, new);
 716                 if (err)
 717                         goto err_out;
 718         }
 719 
 720         old = vma->vm_policy;
 721         vma->vm_policy = new; /* protected by mmap_sem */
 722         mpol_put(old);
 723 
 724         return 0;
 725  err_out:
 726         mpol_put(new);
 727         return err;
 728 }
 729 
 730 /* Step 2: apply policy to a range and do splits. */
 731 static int mbind_range(struct mm_struct *mm, unsigned long start,
 732                        unsigned long end, struct mempolicy *new_pol)
 733 {
 734         struct vm_area_struct *next;
 735         struct vm_area_struct *prev;
 736         struct vm_area_struct *vma;
 737         int err = 0;
 738         pgoff_t pgoff;
 739         unsigned long vmstart;
 740         unsigned long vmend;
 741 
 742         vma = find_vma(mm, start);
 743         if (!vma || vma->vm_start > start)
 744                 return -EFAULT;
 745 
 746         prev = vma->vm_prev;
 747         if (start > vma->vm_start)
 748                 prev = vma;
 749 
 750         for (; vma && vma->vm_start < end; prev = vma, vma = next) {
 751                 next = vma->vm_next;
 752                 vmstart = max(start, vma->vm_start);
 753                 vmend   = min(end, vma->vm_end);
 754 
 755                 if (mpol_equal(vma_policy(vma), new_pol))
 756                         continue;
 757 
 758                 pgoff = vma->vm_pgoff +
 759                         ((vmstart - vma->vm_start) >> PAGE_SHIFT);
 760                 prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
 761                                  vma->anon_vma, vma->vm_file, pgoff,
 762                                  new_pol, vma->vm_userfaultfd_ctx);
 763                 if (prev) {
 764                         vma = prev;
 765                         next = vma->vm_next;
 766                         if (mpol_equal(vma_policy(vma), new_pol))
 767                                 continue;
 768                         /* vma_merge() joined vma && vma->next, case 8 */
 769                         goto replace;
 770                 }
 771                 if (vma->vm_start != vmstart) {
 772                         err = split_vma(vma->vm_mm, vma, vmstart, 1);
 773                         if (err)
 774                                 goto out;
 775                 }
 776                 if (vma->vm_end != vmend) {
 777                         err = split_vma(vma->vm_mm, vma, vmend, 0);
 778                         if (err)
 779                                 goto out;
 780                 }
 781  replace:
 782                 err = vma_replace_policy(vma, new_pol);
 783                 if (err)
 784                         goto out;
 785         }
 786 
 787  out:
 788         return err;
 789 }
 790 
 791 /* Set the process memory policy */
 792 static long do_set_mempolicy(unsigned short mode, unsigned short flags,
 793                              nodemask_t *nodes)
 794 {
 795         struct mempolicy *new, *old;
 796         NODEMASK_SCRATCH(scratch);
 797         int ret;
 798 
 799         if (!scratch)
 800                 return -ENOMEM;
 801 
 802         new = mpol_new(mode, flags, nodes);
 803         if (IS_ERR(new)) {
 804                 ret = PTR_ERR(new);
 805                 goto out;
 806         }
 807 
 808         task_lock(current);
 809         ret = mpol_set_nodemask(new, nodes, scratch);
 810         if (ret) {
 811                 task_unlock(current);
 812                 mpol_put(new);
 813                 goto out;
 814         }
 815         old = current->mempolicy;
 816         current->mempolicy = new;
 817         if (new && new->mode == MPOL_INTERLEAVE)
 818                 current->il_prev = MAX_NUMNODES-1;
 819         task_unlock(current);
 820         mpol_put(old);
 821         ret = 0;
 822 out:
 823         NODEMASK_SCRATCH_FREE(scratch);
 824         return ret;
 825 }
 826 
 827 /*
 828  * Return nodemask for policy for get_mempolicy() query
 829  *
 830  * Called with task's alloc_lock held
 831  */
 832 static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
 833 {
 834         nodes_clear(*nodes);
 835         if (p == &default_policy)
 836                 return;
 837 
 838         switch (p->mode) {
 839         case MPOL_BIND:
 840                 /* Fall through */
 841         case MPOL_INTERLEAVE:
 842                 *nodes = p->v.nodes;
 843                 break;
 844         case MPOL_PREFERRED:
 845                 if (!(p->flags & MPOL_F_LOCAL))
 846                         node_set(p->v.preferred_node, *nodes);
 847                 /* else return empty node mask for local allocation */
 848                 break;
 849         default:
 850                 BUG();
 851         }
 852 }
 853 
 854 static int lookup_node(struct mm_struct *mm, unsigned long addr)
 855 {
 856         struct page *p;
 857         int err;
 858 
 859         int locked = 1;
 860         err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked);
 861         if (err >= 0) {
 862                 err = page_to_nid(p);
 863                 put_page(p);
 864         }
 865         if (locked)
 866                 up_read(&mm->mmap_sem);
 867         return err;
 868 }
 869 
 870 /* Retrieve NUMA policy */
 871 static long do_get_mempolicy(int *policy, nodemask_t *nmask,
 872                              unsigned long addr, unsigned long flags)
 873 {
 874         int err;
 875         struct mm_struct *mm = current->mm;
 876         struct vm_area_struct *vma = NULL;
 877         struct mempolicy *pol = current->mempolicy, *pol_refcount = NULL;
 878 
 879         if (flags &
 880                 ~(unsigned long)(MPOL_F_NODE|MPOL_F_ADDR|MPOL_F_MEMS_ALLOWED))
 881                 return -EINVAL;
 882 
 883         if (flags & MPOL_F_MEMS_ALLOWED) {
 884                 if (flags & (MPOL_F_NODE|MPOL_F_ADDR))
 885                         return -EINVAL;
 886                 *policy = 0;    /* just so it's initialized */
 887                 task_lock(current);
 888                 *nmask  = cpuset_current_mems_allowed;
 889                 task_unlock(current);
 890                 return 0;
 891         }
 892 
 893         if (flags & MPOL_F_ADDR) {
 894                 /*
 895                  * Do NOT fall back to task policy if the
 896                  * vma/shared policy at addr is NULL.  We
 897                  * want to return MPOL_DEFAULT in this case.
 898                  */
 899                 down_read(&mm->mmap_sem);
 900                 vma = find_vma_intersection(mm, addr, addr+1);
 901                 if (!vma) {
 902                         up_read(&mm->mmap_sem);
 903                         return -EFAULT;
 904                 }
 905                 if (vma->vm_ops && vma->vm_ops->get_policy)
 906                         pol = vma->vm_ops->get_policy(vma, addr);
 907                 else
 908                         pol = vma->vm_policy;
 909         } else if (addr)
 910                 return -EINVAL;
 911 
 912         if (!pol)
 913                 pol = &default_policy;  /* indicates default behavior */
 914 
 915         if (flags & MPOL_F_NODE) {
 916                 if (flags & MPOL_F_ADDR) {
 917                         /*
 918                          * Take a refcount on the mpol, lookup_node()
 919                          * wil drop the mmap_sem, so after calling
 920                          * lookup_node() only "pol" remains valid, "vma"
 921                          * is stale.
 922                          */
 923                         pol_refcount = pol;
 924                         vma = NULL;
 925                         mpol_get(pol);
 926                         err = lookup_node(mm, addr);
 927                         if (err < 0)
 928                                 goto out;
 929                         *policy = err;
 930                 } else if (pol == current->mempolicy &&
 931                                 pol->mode == MPOL_INTERLEAVE) {
 932                         *policy = next_node_in(current->il_prev, pol->v.nodes);
 933                 } else {
 934                         err = -EINVAL;
 935                         goto out;
 936                 }
 937         } else {
 938                 *policy = pol == &default_policy ? MPOL_DEFAULT :
 939                                                 pol->mode;
 940                 /*
 941                  * Internal mempolicy flags must be masked off before exposing
 942                  * the policy to userspace.
 943                  */
 944                 *policy |= (pol->flags & MPOL_MODE_FLAGS);
 945         }
 946 
 947         err = 0;
 948         if (nmask) {
 949                 if (mpol_store_user_nodemask(pol)) {
 950                         *nmask = pol->w.user_nodemask;
 951                 } else {
 952                         task_lock(current);
 953                         get_policy_nodemask(pol, nmask);
 954                         task_unlock(current);
 955                 }
 956         }
 957 
 958  out:
 959         mpol_cond_put(pol);
 960         if (vma)
 961                 up_read(&mm->mmap_sem);
 962         if (pol_refcount)
 963                 mpol_put(pol_refcount);
 964         return err;
 965 }
 966 
 967 #ifdef CONFIG_MIGRATION
 968 /*
 969  * page migration, thp tail pages can be passed.
 970  */
 971 static int migrate_page_add(struct page *page, struct list_head *pagelist,
 972                                 unsigned long flags)
 973 {
 974         struct page *head = compound_head(page);
 975         /*
 976          * Avoid migrating a page that is shared with others.
 977          */
 978         if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(head) == 1) {
 979                 if (!isolate_lru_page(head)) {
 980                         list_add_tail(&head->lru, pagelist);
 981                         mod_node_page_state(page_pgdat(head),
 982                                 NR_ISOLATED_ANON + page_is_file_cache(head),
 983                                 hpage_nr_pages(head));
 984                 } else if (flags & MPOL_MF_STRICT) {
 985                         /*
 986                          * Non-movable page may reach here.  And, there may be
 987                          * temporary off LRU pages or non-LRU movable pages.
 988                          * Treat them as unmovable pages since they can't be
 989                          * isolated, so they can't be moved at the moment.  It
 990                          * should return -EIO for this case too.
 991                          */
 992                         return -EIO;
 993                 }
 994         }
 995 
 996         return 0;
 997 }
 998 
 999 /* page allocation callback for NUMA node migration */
1000 struct page *alloc_new_node_page(struct page *page, unsigned long node)
1001 {
1002         if (PageHuge(page))
1003                 return alloc_huge_page_node(page_hstate(compound_head(page)),
1004                                         node);
1005         else if (PageTransHuge(page)) {
1006                 struct page *thp;
1007 
1008                 thp = alloc_pages_node(node,
1009                         (GFP_TRANSHUGE | __GFP_THISNODE),
1010                         HPAGE_PMD_ORDER);
1011                 if (!thp)
1012                         return NULL;
1013                 prep_transhuge_page(thp);
1014                 return thp;
1015         } else
1016                 return __alloc_pages_node(node, GFP_HIGHUSER_MOVABLE |
1017                                                     __GFP_THISNODE, 0);
1018 }
1019 
1020 /*
1021  * Migrate pages from one node to a target node.
1022  * Returns error or the number of pages not migrated.
1023  */
1024 static int migrate_to_node(struct mm_struct *mm, int source, int dest,
1025                            int flags)
1026 {
1027         nodemask_t nmask;
1028         LIST_HEAD(pagelist);
1029         int err = 0;
1030 
1031         nodes_clear(nmask);
1032         node_set(source, nmask);
1033 
1034         /*
1035          * This does not "check" the range but isolates all pages that
1036          * need migration.  Between passing in the full user address
1037          * space range and MPOL_MF_DISCONTIG_OK, this call can not fail.
1038          */
1039         VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)));
1040         queue_pages_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
1041                         flags | MPOL_MF_DISCONTIG_OK, &pagelist);
1042 
1043         if (!list_empty(&pagelist)) {
1044                 err = migrate_pages(&pagelist, alloc_new_node_page, NULL, dest,
1045                                         MIGRATE_SYNC, MR_SYSCALL);
1046                 if (err)
1047                         putback_movable_pages(&pagelist);
1048         }
1049 
1050         return err;
1051 }
1052 
1053 /*
1054  * Move pages between the two nodesets so as to preserve the physical
1055  * layout as much as possible.
1056  *
1057  * Returns the number of page that could not be moved.
1058  */
1059 int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
1060                      const nodemask_t *to, int flags)
1061 {
1062         int busy = 0;
1063         int err;
1064         nodemask_t tmp;
1065 
1066         err = migrate_prep();
1067         if (err)
1068                 return err;
1069 
1070         down_read(&mm->mmap_sem);
1071 
1072         /*
1073          * Find a 'source' bit set in 'tmp' whose corresponding 'dest'
1074          * bit in 'to' is not also set in 'tmp'.  Clear the found 'source'
1075          * bit in 'tmp', and return that <source, dest> pair for migration.
1076          * The pair of nodemasks 'to' and 'from' define the map.
1077          *
1078          * If no pair of bits is found that way, fallback to picking some
1079          * pair of 'source' and 'dest' bits that are not the same.  If the
1080          * 'source' and 'dest' bits are the same, this represents a node
1081          * that will be migrating to itself, so no pages need move.
1082          *
1083          * If no bits are left in 'tmp', or if all remaining bits left
1084          * in 'tmp' correspond to the same bit in 'to', return false
1085          * (nothing left to migrate).
1086          *
1087          * This lets us pick a pair of nodes to migrate between, such that
1088          * if possible the dest node is not already occupied by some other
1089          * source node, minimizing the risk of overloading the memory on a
1090          * node that would happen if we migrated incoming memory to a node
1091          * before migrating outgoing memory source that same node.
1092          *
1093          * A single scan of tmp is sufficient.  As we go, we remember the
1094          * most recent <s, d> pair that moved (s != d).  If we find a pair
1095          * that not only moved, but what's better, moved to an empty slot
1096          * (d is not set in tmp), then we break out then, with that pair.
1097          * Otherwise when we finish scanning from_tmp, we at least have the
1098          * most recent <s, d> pair that moved.  If we get all the way through
1099          * the scan of tmp without finding any node that moved, much less
1100          * moved to an empty node, then there is nothing left worth migrating.
1101          */
1102 
1103         tmp = *from;
1104         while (!nodes_empty(tmp)) {
1105                 int s,d;
1106                 int source = NUMA_NO_NODE;
1107                 int dest = 0;
1108 
1109                 for_each_node_mask(s, tmp) {
1110 
1111                         /*
1112                          * do_migrate_pages() tries to maintain the relative
1113                          * node relationship of the pages established between
1114                          * threads and memory areas.
1115                          *
1116                          * However if the number of source nodes is not equal to
1117                          * the number of destination nodes we can not preserve
1118                          * this node relative relationship.  In that case, skip
1119                          * copying memory from a node that is in the destination
1120                          * mask.
1121                          *
1122                          * Example: [2,3,4] -> [3,4,5] moves everything.
1123                          *          [0-7] - > [3,4,5] moves only 0,1,2,6,7.
1124                          */
1125 
1126                         if ((nodes_weight(*from) != nodes_weight(*to)) &&
1127                                                 (node_isset(s, *to)))
1128                                 continue;
1129 
1130                         d = node_remap(s, *from, *to);
1131                         if (s == d)
1132                                 continue;
1133 
1134                         source = s;     /* Node moved. Memorize */
1135                         dest = d;
1136 
1137                         /* dest not in remaining from nodes? */
1138                         if (!node_isset(dest, tmp))
1139                                 break;
1140                 }
1141                 if (source == NUMA_NO_NODE)
1142                         break;
1143 
1144                 node_clear(source, tmp);
1145                 err = migrate_to_node(mm, source, dest, flags);
1146                 if (err > 0)
1147                         busy += err;
1148                 if (err < 0)
1149                         break;
1150         }
1151         up_read(&mm->mmap_sem);
1152         if (err < 0)
1153                 return err;
1154         return busy;
1155 
1156 }
1157 
1158 /*
1159  * Allocate a new page for page migration based on vma policy.
1160  * Start by assuming the page is mapped by the same vma as contains @start.
1161  * Search forward from there, if not.  N.B., this assumes that the
1162  * list of pages handed to migrate_pages()--which is how we get here--
1163  * is in virtual address order.
1164  */
1165 static struct page *new_page(struct page *page, unsigned long start)
1166 {
1167         struct vm_area_struct *vma;
1168         unsigned long uninitialized_var(address);
1169 
1170         vma = find_vma(current->mm, start);
1171         while (vma) {
1172                 address = page_address_in_vma(page, vma);
1173                 if (address != -EFAULT)
1174                         break;
1175                 vma = vma->vm_next;
1176         }
1177 
1178         if (PageHuge(page)) {
1179                 return alloc_huge_page_vma(page_hstate(compound_head(page)),
1180                                 vma, address);
1181         } else if (PageTransHuge(page)) {
1182                 struct page *thp;
1183 
1184                 thp = alloc_hugepage_vma(GFP_TRANSHUGE, vma, address,
1185                                          HPAGE_PMD_ORDER);
1186                 if (!thp)
1187                         return NULL;
1188                 prep_transhuge_page(thp);
1189                 return thp;
1190         }
1191         /*
1192          * if !vma, alloc_page_vma() will use task or system default policy
1193          */
1194         return alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_RETRY_MAYFAIL,
1195                         vma, address);
1196 }
1197 #else
1198 
1199 static int migrate_page_add(struct page *page, struct list_head *pagelist,
1200                                 unsigned long flags)
1201 {
1202         return -EIO;
1203 }
1204 
1205 int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
1206                      const nodemask_t *to, int flags)
1207 {
1208         return -ENOSYS;
1209 }
1210 
1211 static struct page *new_page(struct page *page, unsigned long start)
1212 {
1213         return NULL;
1214 }
1215 #endif
1216 
1217 static long do_mbind(unsigned long start, unsigned long len,
1218                      unsigned short mode, unsigned short mode_flags,
1219                      nodemask_t *nmask, unsigned long flags)
1220 {
1221         struct mm_struct *mm = current->mm;
1222         struct mempolicy *new;
1223         unsigned long end;
1224         int err;
1225         int ret;
1226         LIST_HEAD(pagelist);
1227 
1228         if (flags & ~(unsigned long)MPOL_MF_VALID)
1229                 return -EINVAL;
1230         if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1231                 return -EPERM;
1232 
1233         if (start & ~PAGE_MASK)
1234                 return -EINVAL;
1235 
1236         if (mode == MPOL_DEFAULT)
1237                 flags &= ~MPOL_MF_STRICT;
1238 
1239         len = (len + PAGE_SIZE - 1) & PAGE_MASK;
1240         end = start + len;
1241 
1242         if (end < start)
1243                 return -EINVAL;
1244         if (end == start)
1245                 return 0;
1246 
1247         new = mpol_new(mode, mode_flags, nmask);
1248         if (IS_ERR(new))
1249                 return PTR_ERR(new);
1250 
1251         if (flags & MPOL_MF_LAZY)
1252                 new->flags |= MPOL_F_MOF;
1253 
1254         /*
1255          * If we are using the default policy then operation
1256          * on discontinuous address spaces is okay after all
1257          */
1258         if (!new)
1259                 flags |= MPOL_MF_DISCONTIG_OK;
1260 
1261         pr_debug("mbind %lx-%lx mode:%d flags:%d nodes:%lx\n",
1262                  start, start + len, mode, mode_flags,
1263                  nmask ? nodes_addr(*nmask)[0] : NUMA_NO_NODE);
1264 
1265         if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
1266 
1267                 err = migrate_prep();
1268                 if (err)
1269                         goto mpol_out;
1270         }
1271         {
1272                 NODEMASK_SCRATCH(scratch);
1273                 if (scratch) {
1274                         down_write(&mm->mmap_sem);
1275                         task_lock(current);
1276                         err = mpol_set_nodemask(new, nmask, scratch);
1277                         task_unlock(current);
1278                         if (err)
1279                                 up_write(&mm->mmap_sem);
1280                 } else
1281                         err = -ENOMEM;
1282                 NODEMASK_SCRATCH_FREE(scratch);
1283         }
1284         if (err)
1285                 goto mpol_out;
1286 
1287         ret = queue_pages_range(mm, start, end, nmask,
1288                           flags | MPOL_MF_INVERT, &pagelist);
1289 
1290         if (ret < 0) {
1291                 err = ret;
1292                 goto up_out;
1293         }
1294 
1295         err = mbind_range(mm, start, end, new);
1296 
1297         if (!err) {
1298                 int nr_failed = 0;
1299 
1300                 if (!list_empty(&pagelist)) {
1301                         WARN_ON_ONCE(flags & MPOL_MF_LAZY);
1302                         nr_failed = migrate_pages(&pagelist, new_page, NULL,
1303                                 start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND);
1304                         if (nr_failed)
1305                                 putback_movable_pages(&pagelist);
1306                 }
1307 
1308                 if ((ret > 0) || (nr_failed && (flags & MPOL_MF_STRICT)))
1309                         err = -EIO;
1310         } else {
1311 up_out:
1312                 if (!list_empty(&pagelist))
1313                         putback_movable_pages(&pagelist);
1314         }
1315 
1316         up_write(&mm->mmap_sem);
1317 mpol_out:
1318         mpol_put(new);
1319         return err;
1320 }
1321 
1322 /*
1323  * User space interface with variable sized bitmaps for nodelists.
1324  */
1325 
1326 /* Copy a node mask from user space. */
1327 static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask,
1328                      unsigned long maxnode)
1329 {
1330         unsigned long k;
1331         unsigned long t;
1332         unsigned long nlongs;
1333         unsigned long endmask;
1334 
1335         --maxnode;
1336         nodes_clear(*nodes);
1337         if (maxnode == 0 || !nmask)
1338                 return 0;
1339         if (maxnode > PAGE_SIZE*BITS_PER_BYTE)
1340                 return -EINVAL;
1341 
1342         nlongs = BITS_TO_LONGS(maxnode);
1343         if ((maxnode % BITS_PER_LONG) == 0)
1344                 endmask = ~0UL;
1345         else
1346                 endmask = (1UL << (maxnode % BITS_PER_LONG)) - 1;
1347 
1348         /*
1349          * When the user specified more nodes than supported just check
1350          * if the non supported part is all zero.
1351          *
1352          * If maxnode have more longs than MAX_NUMNODES, check
1353          * the bits in that area first. And then go through to
1354          * check the rest bits which equal or bigger than MAX_NUMNODES.
1355          * Otherwise, just check bits [MAX_NUMNODES, maxnode).
1356          */
1357         if (nlongs > BITS_TO_LONGS(MAX_NUMNODES)) {
1358                 for (k = BITS_TO_LONGS(MAX_NUMNODES); k < nlongs; k++) {
1359                         if (get_user(t, nmask + k))
1360                                 return -EFAULT;
1361                         if (k == nlongs - 1) {
1362                                 if (t & endmask)
1363                                         return -EINVAL;
1364                         } else if (t)
1365                                 return -EINVAL;
1366                 }
1367                 nlongs = BITS_TO_LONGS(MAX_NUMNODES);
1368                 endmask = ~0UL;
1369         }
1370 
1371         if (maxnode > MAX_NUMNODES && MAX_NUMNODES % BITS_PER_LONG != 0) {
1372                 unsigned long valid_mask = endmask;
1373 
1374                 valid_mask &= ~((1UL << (MAX_NUMNODES % BITS_PER_LONG)) - 1);
1375                 if (get_user(t, nmask + nlongs - 1))
1376                         return -EFAULT;
1377                 if (t & valid_mask)
1378                         return -EINVAL;
1379         }
1380 
1381         if (copy_from_user(nodes_addr(*nodes), nmask, nlongs*sizeof(unsigned long)))
1382                 return -EFAULT;
1383         nodes_addr(*nodes)[nlongs-1] &= endmask;
1384         return 0;
1385 }
1386 
1387 /* Copy a kernel node mask to user space */
1388 static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
1389                               nodemask_t *nodes)
1390 {
1391         unsigned long copy = ALIGN(maxnode-1, 64) / 8;
1392         unsigned int nbytes = BITS_TO_LONGS(nr_node_ids) * sizeof(long);
1393 
1394         if (copy > nbytes) {
1395                 if (copy > PAGE_SIZE)
1396                         return -EINVAL;
1397                 if (clear_user((char __user *)mask + nbytes, copy - nbytes))
1398                         return -EFAULT;
1399                 copy = nbytes;
1400         }
1401         return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0;
1402 }
1403 
1404 static long kernel_mbind(unsigned long start, unsigned long len,
1405                          unsigned long mode, const unsigned long __user *nmask,
1406                          unsigned long maxnode, unsigned int flags)
1407 {
1408         nodemask_t nodes;
1409         int err;
1410         unsigned short mode_flags;
1411 
1412         start = untagged_addr(start);
1413         mode_flags = mode & MPOL_MODE_FLAGS;
1414         mode &= ~MPOL_MODE_FLAGS;
1415         if (mode >= MPOL_MAX)
1416                 return -EINVAL;
1417         if ((mode_flags & MPOL_F_STATIC_NODES) &&
1418             (mode_flags & MPOL_F_RELATIVE_NODES))
1419                 return -EINVAL;
1420         err = get_nodes(&nodes, nmask, maxnode);
1421         if (err)
1422                 return err;
1423         return do_mbind(start, len, mode, mode_flags, &nodes, flags);
1424 }
1425 
1426 SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
1427                 unsigned long, mode, const unsigned long __user *, nmask,
1428                 unsigned long, maxnode, unsigned int, flags)
1429 {
1430         return kernel_mbind(start, len, mode, nmask, maxnode, flags);
1431 }
1432 
1433 /* Set the process memory policy */
1434 static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask,
1435                                  unsigned long maxnode)
1436 {
1437         int err;
1438         nodemask_t nodes;
1439         unsigned short flags;
1440 
1441         flags = mode & MPOL_MODE_FLAGS;
1442         mode &= ~MPOL_MODE_FLAGS;
1443         if ((unsigned int)mode >= MPOL_MAX)
1444                 return -EINVAL;
1445         if ((flags & MPOL_F_STATIC_NODES) && (flags & MPOL_F_RELATIVE_NODES))
1446                 return -EINVAL;
1447         err = get_nodes(&nodes, nmask, maxnode);
1448         if (err)
1449                 return err;
1450         return do_set_mempolicy(mode, flags, &nodes);
1451 }
1452 
1453 SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
1454                 unsigned long, maxnode)
1455 {
1456         return kernel_set_mempolicy(mode, nmask, maxnode);
1457 }
1458 
1459 static int kernel_migrate_pages(pid_t pid, unsigned long maxnode,
1460                                 const unsigned long __user *old_nodes,
1461                                 const unsigned long __user *new_nodes)
1462 {
1463         struct mm_struct *mm = NULL;
1464         struct task_struct *task;
1465         nodemask_t task_nodes;
1466         int err;
1467         nodemask_t *old;
1468         nodemask_t *new;
1469         NODEMASK_SCRATCH(scratch);
1470 
1471         if (!scratch)
1472                 return -ENOMEM;
1473 
1474         old = &scratch->mask1;
1475         new = &scratch->mask2;
1476 
1477         err = get_nodes(old, old_nodes, maxnode);
1478         if (err)
1479                 goto out;
1480 
1481         err = get_nodes(new, new_nodes, maxnode);
1482         if (err)
1483                 goto out;
1484 
1485         /* Find the mm_struct */
1486         rcu_read_lock();
1487         task = pid ? find_task_by_vpid(pid) : current;
1488         if (!task) {
1489                 rcu_read_unlock();
1490                 err = -ESRCH;
1491                 goto out;
1492         }
1493         get_task_struct(task);
1494 
1495         err = -EINVAL;
1496 
1497         /*
1498          * Check if this process has the right to modify the specified process.
1499          * Use the regular "ptrace_may_access()" checks.
1500          */
1501         if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
1502                 rcu_read_unlock();
1503                 err = -EPERM;
1504                 goto out_put;
1505         }
1506         rcu_read_unlock();
1507 
1508         task_nodes = cpuset_mems_allowed(task);
1509         /* Is the user allowed to access the target nodes? */
1510         if (!nodes_subset(*new, task_nodes) && !capable(CAP_SYS_NICE)) {
1511                 err = -EPERM;
1512                 goto out_put;
1513         }
1514 
1515         task_nodes = cpuset_mems_allowed(current);
1516         nodes_and(*new, *new, task_nodes);
1517         if (nodes_empty(*new))
1518                 goto out_put;
1519 
1520         err = security_task_movememory(task);
1521         if (err)
1522                 goto out_put;
1523 
1524         mm = get_task_mm(task);
1525         put_task_struct(task);
1526 
1527         if (!mm) {
1528                 err = -EINVAL;
1529                 goto out;
1530         }
1531 
1532         err = do_migrate_pages(mm, old, new,
1533                 capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
1534 
1535         mmput(mm);
1536 out:
1537         NODEMASK_SCRATCH_FREE(scratch);
1538 
1539         return err;
1540 
1541 out_put:
1542         put_task_struct(task);
1543         goto out;
1544 
1545 }
1546 
1547 SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
1548                 const unsigned long __user *, old_nodes,
1549                 const unsigned long __user *, new_nodes)
1550 {
1551         return kernel_migrate_pages(pid, maxnode, old_nodes, new_nodes);
1552 }
1553 
1554 
1555 /* Retrieve NUMA policy */
1556 static int kernel_get_mempolicy(int __user *policy,
1557                                 unsigned long __user *nmask,
1558                                 unsigned long maxnode,
1559                                 unsigned long addr,
1560                                 unsigned long flags)
1561 {
1562         int err;
1563         int uninitialized_var(pval);
1564         nodemask_t nodes;
1565 
1566         addr = untagged_addr(addr);
1567 
1568         if (nmask != NULL && maxnode < nr_node_ids)
1569                 return -EINVAL;
1570 
1571         err = do_get_mempolicy(&pval, &nodes, addr, flags);
1572 
1573         if (err)
1574                 return err;
1575 
1576         if (policy && put_user(pval, policy))
1577                 return -EFAULT;
1578 
1579         if (nmask)
1580                 err = copy_nodes_to_user(nmask, maxnode, &nodes);
1581 
1582         return err;
1583 }
1584 
1585 SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
1586                 unsigned long __user *, nmask, unsigned long, maxnode,
1587                 unsigned long, addr, unsigned long, flags)
1588 {
1589         return kernel_get_mempolicy(policy, nmask, maxnode, addr, flags);
1590 }
1591 
1592 #ifdef CONFIG_COMPAT
1593 
1594 COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
1595                        compat_ulong_t __user *, nmask,
1596                        compat_ulong_t, maxnode,
1597                        compat_ulong_t, addr, compat_ulong_t, flags)
1598 {
1599         long err;
1600         unsigned long __user *nm = NULL;
1601         unsigned long nr_bits, alloc_size;
1602         DECLARE_BITMAP(bm, MAX_NUMNODES);
1603 
1604         nr_bits = min_t(unsigned long, maxnode-1, nr_node_ids);
1605         alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1606 
1607         if (nmask)
1608                 nm = compat_alloc_user_space(alloc_size);
1609 
1610         err = kernel_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
1611 
1612         if (!err && nmask) {
1613                 unsigned long copy_size;
1614                 copy_size = min_t(unsigned long, sizeof(bm), alloc_size);
1615                 err = copy_from_user(bm, nm, copy_size);
1616                 /* ensure entire bitmap is zeroed */
1617                 err |= clear_user(nmask, ALIGN(maxnode-1, 8) / 8);
1618                 err |= compat_put_bitmap(nmask, bm, nr_bits);
1619         }
1620 
1621         return err;
1622 }
1623 
1624 COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,
1625                        compat_ulong_t, maxnode)
1626 {
1627         unsigned long __user *nm = NULL;
1628         unsigned long nr_bits, alloc_size;
1629         DECLARE_BITMAP(bm, MAX_NUMNODES);
1630 
1631         nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
1632         alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1633 
1634         if (nmask) {
1635                 if (compat_get_bitmap(bm, nmask, nr_bits))
1636                         return -EFAULT;
1637                 nm = compat_alloc_user_space(alloc_size);
1638                 if (copy_to_user(nm, bm, alloc_size))
1639                         return -EFAULT;
1640         }
1641 
1642         return kernel_set_mempolicy(mode, nm, nr_bits+1);
1643 }
1644 
1645 COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
1646                        compat_ulong_t, mode, compat_ulong_t __user *, nmask,
1647                        compat_ulong_t, maxnode, compat_ulong_t, flags)
1648 {
1649         unsigned long __user *nm = NULL;
1650         unsigned long nr_bits, alloc_size;
1651         nodemask_t bm;
1652 
1653         nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
1654         alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1655 
1656         if (nmask) {
1657                 if (compat_get_bitmap(nodes_addr(bm), nmask, nr_bits))
1658                         return -EFAULT;
1659                 nm = compat_alloc_user_space(alloc_size);
1660                 if (copy_to_user(nm, nodes_addr(bm), alloc_size))
1661                         return -EFAULT;
1662         }
1663 
1664         return kernel_mbind(start, len, mode, nm, nr_bits+1, flags);
1665 }
1666 
1667 COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid,
1668                        compat_ulong_t, maxnode,
1669                        const compat_ulong_t __user *, old_nodes,
1670                        const compat_ulong_t __user *, new_nodes)
1671 {
1672         unsigned long __user *old = NULL;
1673         unsigned long __user *new = NULL;
1674         nodemask_t tmp_mask;
1675         unsigned long nr_bits;
1676         unsigned long size;
1677 
1678         nr_bits = min_t(unsigned long, maxnode - 1, MAX_NUMNODES);
1679         size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1680         if (old_nodes) {
1681                 if (compat_get_bitmap(nodes_addr(tmp_mask), old_nodes, nr_bits))
1682                         return -EFAULT;
1683                 old = compat_alloc_user_space(new_nodes ? size * 2 : size);
1684                 if (new_nodes)
1685                         new = old + size / sizeof(unsigned long);
1686                 if (copy_to_user(old, nodes_addr(tmp_mask), size))
1687                         return -EFAULT;
1688         }
1689         if (new_nodes) {
1690                 if (compat_get_bitmap(nodes_addr(tmp_mask), new_nodes, nr_bits))
1691                         return -EFAULT;
1692                 if (new == NULL)
1693                         new = compat_alloc_user_space(size);
1694                 if (copy_to_user(new, nodes_addr(tmp_mask), size))
1695                         return -EFAULT;
1696         }
1697         return kernel_migrate_pages(pid, nr_bits + 1, old, new);
1698 }
1699 
1700 #endif /* CONFIG_COMPAT */
1701 
1702 struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,
1703                                                 unsigned long addr)
1704 {
1705         struct mempolicy *pol = NULL;
1706 
1707         if (vma) {
1708                 if (vma->vm_ops && vma->vm_ops->get_policy) {
1709                         pol = vma->vm_ops->get_policy(vma, addr);
1710                 } else if (vma->vm_policy) {
1711                         pol = vma->vm_policy;
1712 
1713                         /*
1714                          * shmem_alloc_page() passes MPOL_F_SHARED policy with
1715                          * a pseudo vma whose vma->vm_ops=NULL. Take a reference
1716                          * count on these policies which will be dropped by
1717                          * mpol_cond_put() later
1718                          */
1719                         if (mpol_needs_cond_ref(pol))
1720                                 mpol_get(pol);
1721                 }
1722         }
1723 
1724         return pol;
1725 }
1726 
1727 /*
1728  * get_vma_policy(@vma, @addr)
1729  * @vma: virtual memory area whose policy is sought
1730  * @addr: address in @vma for shared policy lookup
1731  *
1732  * Returns effective policy for a VMA at specified address.
1733  * Falls back to current->mempolicy or system default policy, as necessary.
1734  * Shared policies [those marked as MPOL_F_SHARED] require an extra reference
1735  * count--added by the get_policy() vm_op, as appropriate--to protect against
1736  * freeing by another task.  It is the caller's responsibility to free the
1737  * extra reference for shared policies.
1738  */
1739 static struct mempolicy *get_vma_policy(struct vm_area_struct *vma,
1740                                                 unsigned long addr)
1741 {
1742         struct mempolicy *pol = __get_vma_policy(vma, addr);
1743 
1744         if (!pol)
1745                 pol = get_task_policy(current);
1746 
1747         return pol;
1748 }
1749 
1750 bool vma_policy_mof(struct vm_area_struct *vma)
1751 {
1752         struct mempolicy *pol;
1753 
1754         if (vma->vm_ops && vma->vm_ops->get_policy) {
1755                 bool ret = false;
1756 
1757                 pol = vma->vm_ops->get_policy(vma, vma->vm_start);
1758                 if (pol && (pol->flags & MPOL_F_MOF))
1759                         ret = true;
1760                 mpol_cond_put(pol);
1761 
1762                 return ret;
1763         }
1764 
1765         pol = vma->vm_policy;
1766         if (!pol)
1767                 pol = get_task_policy(current);
1768 
1769         return pol->flags & MPOL_F_MOF;
1770 }
1771 
1772 static int apply_policy_zone(struct mempolicy *policy, enum zone_type zone)
1773 {
1774         enum zone_type dynamic_policy_zone = policy_zone;
1775 
1776         BUG_ON(dynamic_policy_zone == ZONE_MOVABLE);
1777 
1778         /*
1779          * if policy->v.nodes has movable memory only,
1780          * we apply policy when gfp_zone(gfp) = ZONE_MOVABLE only.
1781          *
1782          * policy->v.nodes is intersect with node_states[N_MEMORY].
1783          * so if the following test faile, it implies
1784          * policy->v.nodes has movable memory only.
1785          */
1786         if (!nodes_intersects(policy->v.nodes, node_states[N_HIGH_MEMORY]))
1787                 dynamic_policy_zone = ZONE_MOVABLE;
1788 
1789         return zone >= dynamic_policy_zone;
1790 }
1791 
1792 /*
1793  * Return a nodemask representing a mempolicy for filtering nodes for
1794  * page allocation
1795  */
1796 static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
1797 {
1798         /* Lower zones don't get a nodemask applied for MPOL_BIND */
1799         if (unlikely(policy->mode == MPOL_BIND) &&
1800                         apply_policy_zone(policy, gfp_zone(gfp)) &&
1801                         cpuset_nodemask_valid_mems_allowed(&policy->v.nodes))
1802                 return &policy->v.nodes;
1803 
1804         return NULL;
1805 }
1806 
1807 /* Return the node id preferred by the given mempolicy, or the given id */
1808 static int policy_node(gfp_t gfp, struct mempolicy *policy,
1809                                                                 int nd)
1810 {
1811         if (policy->mode == MPOL_PREFERRED && !(policy->flags & MPOL_F_LOCAL))
1812                 nd = policy->v.preferred_node;
1813         else {
1814                 /*
1815                  * __GFP_THISNODE shouldn't even be used with the bind policy
1816                  * because we might easily break the expectation to stay on the
1817                  * requested node and not break the policy.
1818                  */
1819                 WARN_ON_ONCE(policy->mode == MPOL_BIND && (gfp & __GFP_THISNODE));
1820         }
1821 
1822         return nd;
1823 }
1824 
1825 /* Do dynamic interleaving for a process */
1826 static unsigned interleave_nodes(struct mempolicy *policy)
1827 {
1828         unsigned next;
1829         struct task_struct *me = current;
1830 
1831         next = next_node_in(me->il_prev, policy->v.nodes);
1832         if (next < MAX_NUMNODES)
1833                 me->il_prev = next;
1834         return next;
1835 }
1836 
1837 /*
1838  * Depending on the memory policy provide a node from which to allocate the
1839  * next slab entry.
1840  */
1841 unsigned int mempolicy_slab_node(void)
1842 {
1843         struct mempolicy *policy;
1844         int node = numa_mem_id();
1845 
1846         if (in_interrupt())
1847                 return node;
1848 
1849         policy = current->mempolicy;
1850         if (!policy || policy->flags & MPOL_F_LOCAL)
1851                 return node;
1852 
1853         switch (policy->mode) {
1854         case MPOL_PREFERRED:
1855                 /*
1856                  * handled MPOL_F_LOCAL above
1857                  */
1858                 return policy->v.preferred_node;
1859 
1860         case MPOL_INTERLEAVE:
1861                 return interleave_nodes(policy);
1862 
1863         case MPOL_BIND: {
1864                 struct zoneref *z;
1865 
1866                 /*
1867                  * Follow bind policy behavior and start allocation at the
1868                  * first node.
1869                  */
1870                 struct zonelist *zonelist;
1871                 enum zone_type highest_zoneidx = gfp_zone(GFP_KERNEL);
1872                 zonelist = &NODE_DATA(node)->node_zonelists[ZONELIST_FALLBACK];
1873                 z = first_zones_zonelist(zonelist, highest_zoneidx,
1874                                                         &policy->v.nodes);
1875                 return z->zone ? zone_to_nid(z->zone) : node;
1876         }
1877 
1878         default:
1879                 BUG();
1880         }
1881 }
1882 
1883 /*
1884  * Do static interleaving for a VMA with known offset @n.  Returns the n'th
1885  * node in pol->v.nodes (starting from n=0), wrapping around if n exceeds the
1886  * number of present nodes.
1887  */
1888 static unsigned offset_il_node(struct mempolicy *pol, unsigned long n)
1889 {
1890         unsigned nnodes = nodes_weight(pol->v.nodes);
1891         unsigned target;
1892         int i;
1893         int nid;
1894 
1895         if (!nnodes)
1896                 return numa_node_id();
1897         target = (unsigned int)n % nnodes;
1898         nid = first_node(pol->v.nodes);
1899         for (i = 0; i < target; i++)
1900                 nid = next_node(nid, pol->v.nodes);
1901         return nid;
1902 }
1903 
1904 /* Determine a node number for interleave */
1905 static inline unsigned interleave_nid(struct mempolicy *pol,
1906                  struct vm_area_struct *vma, unsigned long addr, int shift)
1907 {
1908         if (vma) {
1909                 unsigned long off;
1910 
1911                 /*
1912                  * for small pages, there is no difference between
1913                  * shift and PAGE_SHIFT, so the bit-shift is safe.
1914                  * for huge pages, since vm_pgoff is in units of small
1915                  * pages, we need to shift off the always 0 bits to get
1916                  * a useful offset.
1917                  */
1918                 BUG_ON(shift < PAGE_SHIFT);
1919                 off = vma->vm_pgoff >> (shift - PAGE_SHIFT);
1920                 off += (addr - vma->vm_start) >> shift;
1921                 return offset_il_node(pol, off);
1922         } else
1923                 return interleave_nodes(pol);
1924 }
1925 
1926 #ifdef CONFIG_HUGETLBFS
1927 /*
1928  * huge_node(@vma, @addr, @gfp_flags, @mpol)
1929  * @vma: virtual memory area whose policy is sought
1930  * @addr: address in @vma for shared policy lookup and interleave policy
1931  * @gfp_flags: for requested zone
1932  * @mpol: pointer to mempolicy pointer for reference counted mempolicy
1933  * @nodemask: pointer to nodemask pointer for MPOL_BIND nodemask
1934  *
1935  * Returns a nid suitable for a huge page allocation and a pointer
1936  * to the struct mempolicy for conditional unref after allocation.
1937  * If the effective policy is 'BIND, returns a pointer to the mempolicy's
1938  * @nodemask for filtering the zonelist.
1939  *
1940  * Must be protected by read_mems_allowed_begin()
1941  */
1942 int huge_node(struct vm_area_struct *vma, unsigned long addr, gfp_t gfp_flags,
1943                                 struct mempolicy **mpol, nodemask_t **nodemask)
1944 {
1945         int nid;
1946 
1947         *mpol = get_vma_policy(vma, addr);
1948         *nodemask = NULL;       /* assume !MPOL_BIND */
1949 
1950         if (unlikely((*mpol)->mode == MPOL_INTERLEAVE)) {
1951                 nid = interleave_nid(*mpol, vma, addr,
1952                                         huge_page_shift(hstate_vma(vma)));
1953         } else {
1954                 nid = policy_node(gfp_flags, *mpol, numa_node_id());
1955                 if ((*mpol)->mode == MPOL_BIND)
1956                         *nodemask = &(*mpol)->v.nodes;
1957         }
1958         return nid;
1959 }
1960 
1961 /*
1962  * init_nodemask_of_mempolicy
1963  *
1964  * If the current task's mempolicy is "default" [NULL], return 'false'
1965  * to indicate default policy.  Otherwise, extract the policy nodemask
1966  * for 'bind' or 'interleave' policy into the argument nodemask, or
1967  * initialize the argument nodemask to contain the single node for
1968  * 'preferred' or 'local' policy and return 'true' to indicate presence
1969  * of non-default mempolicy.
1970  *
1971  * We don't bother with reference counting the mempolicy [mpol_get/put]
1972  * because the current task is examining it's own mempolicy and a task's
1973  * mempolicy is only ever changed by the task itself.
1974  *
1975  * N.B., it is the caller's responsibility to free a returned nodemask.
1976  */
1977 bool init_nodemask_of_mempolicy(nodemask_t *mask)
1978 {
1979         struct mempolicy *mempolicy;
1980         int nid;
1981 
1982         if (!(mask && current->mempolicy))
1983                 return false;
1984 
1985         task_lock(current);
1986         mempolicy = current->mempolicy;
1987         switch (mempolicy->mode) {
1988         case MPOL_PREFERRED:
1989                 if (mempolicy->flags & MPOL_F_LOCAL)
1990                         nid = numa_node_id();
1991                 else
1992                         nid = mempolicy->v.preferred_node;
1993                 init_nodemask_of_node(mask, nid);
1994                 break;
1995 
1996         case MPOL_BIND:
1997                 /* Fall through */
1998         case MPOL_INTERLEAVE:
1999                 *mask =  mempolicy->v.nodes;
2000                 break;
2001 
2002         default:
2003                 BUG();
2004         }
2005         task_unlock(current);
2006 
2007         return true;
2008 }
2009 #endif
2010 
2011 /*
2012  * mempolicy_nodemask_intersects
2013  *
2014  * If tsk's mempolicy is "default" [NULL], return 'true' to indicate default
2015  * policy.  Otherwise, check for intersection between mask and the policy
2016  * nodemask for 'bind' or 'interleave' policy.  For 'perferred' or 'local'
2017  * policy, always return true since it may allocate elsewhere on fallback.
2018  *
2019  * Takes task_lock(tsk) to prevent freeing of its mempolicy.
2020  */
2021 bool mempolicy_nodemask_intersects(struct task_struct *tsk,
2022                                         const nodemask_t *mask)
2023 {
2024         struct mempolicy *mempolicy;
2025         bool ret = true;
2026 
2027         if (!mask)
2028                 return ret;
2029         task_lock(tsk);
2030         mempolicy = tsk->mempolicy;
2031         if (!mempolicy)
2032                 goto out;
2033 
2034         switch (mempolicy->mode) {
2035         case MPOL_PREFERRED:
2036                 /*
2037                  * MPOL_PREFERRED and MPOL_F_LOCAL are only preferred nodes to
2038                  * allocate from, they may fallback to other nodes when oom.
2039                  * Thus, it's possible for tsk to have allocated memory from
2040                  * nodes in mask.
2041                  */
2042                 break;
2043         case MPOL_BIND:
2044         case MPOL_INTERLEAVE:
2045                 ret = nodes_intersects(mempolicy->v.nodes, *mask);
2046                 break;
2047         default:
2048                 BUG();
2049         }
2050 out:
2051         task_unlock(tsk);
2052         return ret;
2053 }
2054 
2055 /* Allocate a page in interleaved policy.
2056    Own path because it needs to do special accounting. */
2057 static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
2058                                         unsigned nid)
2059 {
2060         struct page *page;
2061 
2062         page = __alloc_pages(gfp, order, nid);
2063         /* skip NUMA_INTERLEAVE_HIT counter update if numa stats is disabled */
2064         if (!static_branch_likely(&vm_numa_stat_key))
2065                 return page;
2066         if (page && page_to_nid(page) == nid) {
2067                 preempt_disable();
2068                 __inc_numa_state(page_zone(page), NUMA_INTERLEAVE_HIT);
2069                 preempt_enable();
2070         }
2071         return page;
2072 }
2073 
2074 /**
2075  *      alloc_pages_vma - Allocate a page for a VMA.
2076  *
2077  *      @gfp:
2078  *      %GFP_USER    user allocation.
2079  *      %GFP_KERNEL  kernel allocations,
2080  *      %GFP_HIGHMEM highmem/user allocations,
2081  *      %GFP_FS      allocation should not call back into a file system.
2082  *      %GFP_ATOMIC  don't sleep.
2083  *
2084  *      @order:Order of the GFP allocation.
2085  *      @vma:  Pointer to VMA or NULL if not available.
2086  *      @addr: Virtual Address of the allocation. Must be inside the VMA.
2087  *      @node: Which node to prefer for allocation (modulo policy).
2088  *      @hugepage: for hugepages try only the preferred node if possible
2089  *
2090  *      This function allocates a page from the kernel page pool and applies
2091  *      a NUMA policy associated with the VMA or the current process.
2092  *      When VMA is not NULL caller must hold down_read on the mmap_sem of the
2093  *      mm_struct of the VMA to prevent it from going away. Should be used for
2094  *      all allocations for pages that will be mapped into user space. Returns
2095  *      NULL when no page can be allocated.
2096  */
2097 struct page *
2098 alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
2099                 unsigned long addr, int node, bool hugepage)
2100 {
2101         struct mempolicy *pol;
2102         struct page *page;
2103         int preferred_nid;
2104         nodemask_t *nmask;
2105 
2106         pol = get_vma_policy(vma, addr);
2107 
2108         if (pol->mode == MPOL_INTERLEAVE) {
2109                 unsigned nid;
2110 
2111                 nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
2112                 mpol_cond_put(pol);
2113                 page = alloc_page_interleave(gfp, order, nid);
2114                 goto out;
2115         }
2116 
2117         if (unlikely(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hugepage)) {
2118                 int hpage_node = node;
2119 
2120                 /*
2121                  * For hugepage allocation and non-interleave policy which
2122                  * allows the current node (or other explicitly preferred
2123                  * node) we only try to allocate from the current/preferred
2124                  * node and don't fall back to other nodes, as the cost of
2125                  * remote accesses would likely offset THP benefits.
2126                  *
2127                  * If the policy is interleave, or does not allow the current
2128                  * node in its nodemask, we allocate the standard way.
2129                  */
2130                 if (pol->mode == MPOL_PREFERRED && !(pol->flags & MPOL_F_LOCAL))
2131                         hpage_node = pol->v.preferred_node;
2132 
2133                 nmask = policy_nodemask(gfp, pol);
2134                 if (!nmask || node_isset(hpage_node, *nmask)) {
2135                         mpol_cond_put(pol);
2136                         page = __alloc_pages_node(hpage_node,
2137                                                 gfp | __GFP_THISNODE, order);
2138 
2139                         /*
2140                          * If hugepage allocations are configured to always
2141                          * synchronous compact or the vma has been madvised
2142                          * to prefer hugepage backing, retry allowing remote
2143                          * memory as well.
2144                          */
2145                         if (!page && (gfp & __GFP_DIRECT_RECLAIM))
2146                                 page = __alloc_pages_node(hpage_node,
2147                                                 gfp | __GFP_NORETRY, order);
2148 
2149                         goto out;
2150                 }
2151         }
2152 
2153         nmask = policy_nodemask(gfp, pol);
2154         preferred_nid = policy_node(gfp, pol, node);
2155         page = __alloc_pages_nodemask(gfp, order, preferred_nid, nmask);
2156         mpol_cond_put(pol);
2157 out:
2158         return page;
2159 }
2160 EXPORT_SYMBOL(alloc_pages_vma);
2161 
2162 /**
2163  *      alloc_pages_current - Allocate pages.
2164  *
2165  *      @gfp:
2166  *              %GFP_USER   user allocation,
2167  *              %GFP_KERNEL kernel allocation,
2168  *              %GFP_HIGHMEM highmem allocation,
2169  *              %GFP_FS     don't call back into a file system.
2170  *              %GFP_ATOMIC don't sleep.
2171  *      @order: Power of two of allocation size in pages. 0 is a single page.
2172  *
2173  *      Allocate a page from the kernel page pool.  When not in
2174  *      interrupt context and apply the current process NUMA policy.
2175  *      Returns NULL when no page can be allocated.
2176  */
2177 struct page *alloc_pages_current(gfp_t gfp, unsigned order)
2178 {
2179         struct mempolicy *pol = &default_policy;
2180         struct page *page;
2181 
2182         if (!in_interrupt() && !(gfp & __GFP_THISNODE))
2183                 pol = get_task_policy(current);
2184 
2185         /*
2186          * No reference counting needed for current->mempolicy
2187          * nor system default_policy
2188          */
2189         if (pol->mode == MPOL_INTERLEAVE)
2190                 page = alloc_page_interleave(gfp, order, interleave_nodes(pol));
2191         else
2192                 page = __alloc_pages_nodemask(gfp, order,
2193                                 policy_node(gfp, pol, numa_node_id()),
2194                                 policy_nodemask(gfp, pol));
2195 
2196         return page;
2197 }
2198 EXPORT_SYMBOL(alloc_pages_current);
2199 
2200 int vma_dup_policy(struct vm_area_struct *src, struct vm_area_struct *dst)
2201 {
2202         struct mempolicy *pol = mpol_dup(vma_policy(src));
2203 
2204         if (IS_ERR(pol))
2205                 return PTR_ERR(pol);
2206         dst->vm_policy = pol;
2207         return 0;
2208 }
2209 
2210 /*
2211  * If mpol_dup() sees current->cpuset == cpuset_being_rebound, then it
2212  * rebinds the mempolicy its copying by calling mpol_rebind_policy()
2213  * with the mems_allowed returned by cpuset_mems_allowed().  This
2214  * keeps mempolicies cpuset relative after its cpuset moves.  See
2215  * further kernel/cpuset.c update_nodemask().
2216  *
2217  * current's mempolicy may be rebinded by the other task(the task that changes
2218  * cpuset's mems), so we needn't do rebind work for current task.
2219  */
2220 
2221 /* Slow path of a mempolicy duplicate */
2222 struct mempolicy *__mpol_dup(struct mempolicy *old)
2223 {
2224         struct mempolicy *new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
2225 
2226         if (!new)
2227                 return ERR_PTR(-ENOMEM);
2228 
2229         /* task's mempolicy is protected by alloc_lock */
2230         if (old == current->mempolicy) {
2231                 task_lock(current);
2232                 *new = *old;
2233                 task_unlock(current);
2234         } else
2235                 *new = *old;
2236 
2237         if (current_cpuset_is_being_rebound()) {
2238                 nodemask_t mems = cpuset_mems_allowed(current);
2239                 mpol_rebind_policy(new, &mems);
2240         }
2241         atomic_set(&new->refcnt, 1);
2242         return new;
2243 }
2244 
2245 /* Slow path of a mempolicy comparison */
2246 bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
2247 {
2248         if (!a || !b)
2249                 return false;
2250         if (a->mode != b->mode)
2251                 return false;
2252         if (a->flags != b->flags)
2253                 return false;
2254         if (mpol_store_user_nodemask(a))
2255                 if (!nodes_equal(a->w.user_nodemask, b->w.user_nodemask))
2256                         return false;
2257 
2258         switch (a->mode) {
2259         case MPOL_BIND:
2260                 /* Fall through */
2261         case MPOL_INTERLEAVE:
2262                 return !!nodes_equal(a->v.nodes, b->v.nodes);
2263         case MPOL_PREFERRED:
2264                 /* a's ->flags is the same as b's */
2265                 if (a->flags & MPOL_F_LOCAL)
2266                         return true;
2267                 return a->v.preferred_node == b->v.preferred_node;
2268         default:
2269                 BUG();
2270                 return false;
2271         }
2272 }
2273 
2274 /*
2275  * Shared memory backing store policy support.
2276  *
2277  * Remember policies even when nobody has shared memory mapped.
2278  * The policies are kept in Red-Black tree linked from the inode.
2279  * They are protected by the sp->lock rwlock, which should be held
2280  * for any accesses to the tree.
2281  */
2282 
2283 /*
2284  * lookup first element intersecting start-end.  Caller holds sp->lock for
2285  * reading or for writing
2286  */
2287 static struct sp_node *
2288 sp_lookup(struct shared_policy *sp, unsigned long start, unsigned long end)
2289 {
2290         struct rb_node *n = sp->root.rb_node;
2291 
2292         while (n) {
2293                 struct sp_node *p = rb_entry(n, struct sp_node, nd);
2294 
2295                 if (start >= p->end)
2296                         n = n->rb_right;
2297                 else if (end <= p->start)
2298                         n = n->rb_left;
2299                 else
2300                         break;
2301         }
2302         if (!n)
2303                 return NULL;
2304         for (;;) {
2305                 struct sp_node *w = NULL;
2306                 struct rb_node *prev = rb_prev(n);
2307                 if (!prev)
2308                         break;
2309                 w = rb_entry(prev, struct sp_node, nd);
2310                 if (w->end <= start)
2311                         break;
2312                 n = prev;
2313         }
2314         return rb_entry(n, struct sp_node, nd);
2315 }
2316 
2317 /*
2318  * Insert a new shared policy into the list.  Caller holds sp->lock for
2319  * writing.
2320  */
2321 static void sp_insert(struct shared_policy *sp, struct sp_node *new)
2322 {
2323         struct rb_node **p = &sp->root.rb_node;
2324         struct rb_node *parent = NULL;
2325         struct sp_node *nd;
2326 
2327         while (*p) {
2328                 parent = *p;
2329                 nd = rb_entry(parent, struct sp_node, nd);
2330                 if (new->start < nd->start)
2331                         p = &(*p)->rb_left;
2332                 else if (new->end > nd->end)
2333                         p = &(*p)->rb_right;
2334                 else
2335                         BUG();
2336         }
2337         rb_link_node(&new->nd, parent, p);
2338         rb_insert_color(&new->nd, &sp->root);
2339         pr_debug("inserting %lx-%lx: %d\n", new->start, new->end,
2340                  new->policy ? new->policy->mode : 0);
2341 }
2342 
2343 /* Find shared policy intersecting idx */
2344 struct mempolicy *
2345 mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)
2346 {
2347         struct mempolicy *pol = NULL;
2348         struct sp_node *sn;
2349 
2350         if (!sp->root.rb_node)
2351                 return NULL;
2352         read_lock(&sp->lock);
2353         sn = sp_lookup(sp, idx, idx+1);
2354         if (sn) {
2355                 mpol_get(sn->policy);
2356                 pol = sn->policy;
2357         }
2358         read_unlock(&sp->lock);
2359         return pol;
2360 }
2361 
2362 static void sp_free(struct sp_node *n)
2363 {
2364         mpol_put(n->policy);
2365         kmem_cache_free(sn_cache, n);
2366 }
2367 
2368 /**
2369  * mpol_misplaced - check whether current page node is valid in policy
2370  *
2371  * @page: page to be checked
2372  * @vma: vm area where page mapped
2373  * @addr: virtual address where page mapped
2374  *
2375  * Lookup current policy node id for vma,addr and "compare to" page's
2376  * node id.
2377  *
2378  * Returns:
2379  *      -1      - not misplaced, page is in the right node
2380  *      node    - node id where the page should be
2381  *
2382  * Policy determination "mimics" alloc_page_vma().
2383  * Called from fault path where we know the vma and faulting address.
2384  */
2385 int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long addr)
2386 {
2387         struct mempolicy *pol;
2388         struct zoneref *z;
2389         int curnid = page_to_nid(page);
2390         unsigned long pgoff;
2391         int thiscpu = raw_smp_processor_id();
2392         int thisnid = cpu_to_node(thiscpu);
2393         int polnid = NUMA_NO_NODE;
2394         int ret = -1;
2395 
2396         pol = get_vma_policy(vma, addr);
2397         if (!(pol->flags & MPOL_F_MOF))
2398                 goto out;
2399 
2400         switch (pol->mode) {
2401         case MPOL_INTERLEAVE:
2402                 pgoff = vma->vm_pgoff;
2403                 pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;
2404                 polnid = offset_il_node(pol, pgoff);
2405                 break;
2406 
2407         case MPOL_PREFERRED:
2408                 if (pol->flags & MPOL_F_LOCAL)
2409                         polnid = numa_node_id();
2410                 else
2411                         polnid = pol->v.preferred_node;
2412                 break;
2413 
2414         case MPOL_BIND:
2415 
2416                 /*
2417                  * allows binding to multiple nodes.
2418                  * use current page if in policy nodemask,
2419                  * else select nearest allowed node, if any.
2420                  * If no allowed nodes, use current [!misplaced].
2421                  */
2422                 if (node_isset(curnid, pol->v.nodes))
2423                         goto out;
2424                 z = first_zones_zonelist(
2425                                 node_zonelist(numa_node_id(), GFP_HIGHUSER),
2426                                 gfp_zone(GFP_HIGHUSER),
2427                                 &pol->v.nodes);
2428                 polnid = zone_to_nid(z->zone);
2429                 break;
2430 
2431         default:
2432                 BUG();
2433         }
2434 
2435         /* Migrate the page towards the node whose CPU is referencing it */
2436         if (pol->flags & MPOL_F_MORON) {
2437                 polnid = thisnid;
2438 
2439                 if (!should_numa_migrate_memory(current, page, curnid, thiscpu))
2440                         goto out;
2441         }
2442 
2443         if (curnid != polnid)
2444                 ret = polnid;
2445 out:
2446         mpol_cond_put(pol);
2447 
2448         return ret;
2449 }
2450 
2451 /*
2452  * Drop the (possibly final) reference to task->mempolicy.  It needs to be
2453  * dropped after task->mempolicy is set to NULL so that any allocation done as
2454  * part of its kmem_cache_free(), such as by KASAN, doesn't reference a freed
2455  * policy.
2456  */
2457 void mpol_put_task_policy(struct task_struct *task)
2458 {
2459         struct mempolicy *pol;
2460 
2461         task_lock(task);
2462         pol = task->mempolicy;
2463         task->mempolicy = NULL;
2464         task_unlock(task);
2465         mpol_put(pol);
2466 }
2467 
2468 static void sp_delete(struct shared_policy *sp, struct sp_node *n)
2469 {
2470         pr_debug("deleting %lx-l%lx\n", n->start, n->end);
2471         rb_erase(&n->nd, &sp->root);
2472         sp_free(n);
2473 }
2474 
2475 static void sp_node_init(struct sp_node *node, unsigned long start,
2476                         unsigned long end, struct mempolicy *pol)
2477 {
2478         node->start = start;
2479         node->end = end;
2480         node->policy = pol;
2481 }
2482 
2483 static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
2484                                 struct mempolicy *pol)
2485 {
2486         struct sp_node *n;
2487         struct mempolicy *newpol;
2488 
2489         n = kmem_cache_alloc(sn_cache, GFP_KERNEL);
2490         if (!n)
2491                 return NULL;
2492 
2493         newpol = mpol_dup(pol);
2494         if (IS_ERR(newpol)) {
2495                 kmem_cache_free(sn_cache, n);
2496                 return NULL;
2497         }
2498         newpol->flags |= MPOL_F_SHARED;
2499         sp_node_init(n, start, end, newpol);
2500 
2501         return n;
2502 }
2503 
2504 /* Replace a policy range. */
2505 static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
2506                                  unsigned long end, struct sp_node *new)
2507 {
2508         struct sp_node *n;
2509         struct sp_node *n_new = NULL;
2510         struct mempolicy *mpol_new = NULL;
2511         int ret = 0;
2512 
2513 restart:
2514         write_lock(&sp->lock);
2515         n = sp_lookup(sp, start, end);
2516         /* Take care of old policies in the same range. */
2517         while (n && n->start < end) {
2518                 struct rb_node *next = rb_next(&n->nd);
2519                 if (n->start >= start) {
2520                         if (n->end <= end)
2521                                 sp_delete(sp, n);
2522                         else
2523                                 n->start = end;
2524                 } else {
2525                         /* Old policy spanning whole new range. */
2526                         if (n->end > end) {
2527                                 if (!n_new)
2528                                         goto alloc_new;
2529 
2530                                 *mpol_new = *n->policy;
2531                                 atomic_set(&mpol_new->refcnt, 1);
2532                                 sp_node_init(n_new, end, n->end, mpol_new);
2533                                 n->end = start;
2534                                 sp_insert(sp, n_new);
2535                                 n_new = NULL;
2536                                 mpol_new = NULL;
2537                                 break;
2538                         } else
2539                                 n->end = start;
2540                 }
2541                 if (!next)
2542                         break;
2543                 n = rb_entry(next, struct sp_node, nd);
2544         }
2545         if (new)
2546                 sp_insert(sp, new);
2547         write_unlock(&sp->lock);
2548         ret = 0;
2549 
2550 err_out:
2551         if (mpol_new)
2552                 mpol_put(mpol_new);
2553         if (n_new)
2554                 kmem_cache_free(sn_cache, n_new);
2555 
2556         return ret;
2557 
2558 alloc_new:
2559         write_unlock(&sp->lock);
2560         ret = -ENOMEM;
2561         n_new = kmem_cache_alloc(sn_cache, GFP_KERNEL);
2562         if (!n_new)
2563                 goto err_out;
2564         mpol_new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
2565         if (!mpol_new)
2566                 goto err_out;
2567         goto restart;
2568 }
2569 
2570 /**
2571  * mpol_shared_policy_init - initialize shared policy for inode
2572  * @sp: pointer to inode shared policy
2573  * @mpol:  struct mempolicy to install
2574  *
2575  * Install non-NULL @mpol in inode's shared policy rb-tree.
2576  * On entry, the current task has a reference on a non-NULL @mpol.
2577  * This must be released on exit.
2578  * This is called at get_inode() calls and we can use GFP_KERNEL.
2579  */
2580 void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
2581 {
2582         int ret;
2583 
2584         sp->root = RB_ROOT;             /* empty tree == default mempolicy */
2585         rwlock_init(&sp->lock);
2586 
2587         if (mpol) {
2588                 struct vm_area_struct pvma;
2589                 struct mempolicy *new;
2590                 NODEMASK_SCRATCH(scratch);
2591 
2592                 if (!scratch)
2593                         goto put_mpol;
2594                 /* contextualize the tmpfs mount point mempolicy */
2595                 new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
2596                 if (IS_ERR(new))
2597                         goto free_scratch; /* no valid nodemask intersection */
2598 
2599                 task_lock(current);
2600                 ret = mpol_set_nodemask(new, &mpol->w.user_nodemask, scratch);
2601                 task_unlock(current);
2602                 if (ret)
2603                         goto put_new;
2604 
2605                 /* Create pseudo-vma that contains just the policy */
2606                 vma_init(&pvma, NULL);
2607                 pvma.vm_end = TASK_SIZE;        /* policy covers entire file */
2608                 mpol_set_shared_policy(sp, &pvma, new); /* adds ref */
2609 
2610 put_new:
2611                 mpol_put(new);                  /* drop initial ref */
2612 free_scratch:
2613                 NODEMASK_SCRATCH_FREE(scratch);
2614 put_mpol:
2615                 mpol_put(mpol); /* drop our incoming ref on sb mpol */
2616         }
2617 }
2618 
2619 int mpol_set_shared_policy(struct shared_policy *info,
2620                         struct vm_area_struct *vma, struct mempolicy *npol)
2621 {
2622         int err;
2623         struct sp_node *new = NULL;
2624         unsigned long sz = vma_pages(vma);
2625 
2626         pr_debug("set_shared_policy %lx sz %lu %d %d %lx\n",
2627                  vma->vm_pgoff,
2628                  sz, npol ? npol->mode : -1,
2629                  npol ? npol->flags : -1,
2630                  npol ? nodes_addr(npol->v.nodes)[0] : NUMA_NO_NODE);
2631 
2632         if (npol) {
2633                 new = sp_alloc(vma->vm_pgoff, vma->vm_pgoff + sz, npol);
2634                 if (!new)
2635                         return -ENOMEM;
2636         }
2637         err = shared_policy_replace(info, vma->vm_pgoff, vma->vm_pgoff+sz, new);
2638         if (err && new)
2639                 sp_free(new);
2640         return err;
2641 }
2642 
2643 /* Free a backing policy store on inode delete. */
2644 void mpol_free_shared_policy(struct shared_policy *p)
2645 {
2646         struct sp_node *n;
2647         struct rb_node *next;
2648 
2649         if (!p->root.rb_node)
2650                 return;
2651         write_lock(&p->lock);
2652         next = rb_first(&p->root);
2653         while (next) {
2654                 n = rb_entry(next, struct sp_node, nd);
2655                 next = rb_next(&n->nd);
2656                 sp_delete(p, n);
2657         }
2658         write_unlock(&p->lock);
2659 }
2660 
2661 #ifdef CONFIG_NUMA_BALANCING
2662 static int __initdata numabalancing_override;
2663 
2664 static void __init check_numabalancing_enable(void)
2665 {
2666         bool numabalancing_default = false;
2667 
2668         if (IS_ENABLED(CONFIG_NUMA_BALANCING_DEFAULT_ENABLED))
2669                 numabalancing_default = true;
2670 
2671         /* Parsed by setup_numabalancing. override == 1 enables, -1 disables */
2672         if (numabalancing_override)
2673                 set_numabalancing_state(numabalancing_override == 1);
2674 
2675         if (num_online_nodes() > 1 && !numabalancing_override) {
2676                 pr_info("%s automatic NUMA balancing. Configure with numa_balancing= or the kernel.numa_balancing sysctl\n",
2677                         numabalancing_default ? "Enabling" : "Disabling");
2678                 set_numabalancing_state(numabalancing_default);
2679         }
2680 }
2681 
2682 static int __init setup_numabalancing(char *str)
2683 {
2684         int ret = 0;
2685         if (!str)
2686                 goto out;
2687 
2688         if (!strcmp(str, "enable")) {
2689                 numabalancing_override = 1;
2690                 ret = 1;
2691         } else if (!strcmp(str, "disable")) {
2692                 numabalancing_override = -1;
2693                 ret = 1;
2694         }
2695 out:
2696         if (!ret)
2697                 pr_warn("Unable to parse numa_balancing=\n");
2698 
2699         return ret;
2700 }
2701 __setup("numa_balancing=", setup_numabalancing);
2702 #else
2703 static inline void __init check_numabalancing_enable(void)
2704 {
2705 }
2706 #endif /* CONFIG_NUMA_BALANCING */
2707 
2708 /* assumes fs == KERNEL_DS */
2709 void __init numa_policy_init(void)
2710 {
2711         nodemask_t interleave_nodes;
2712         unsigned long largest = 0;
2713         int nid, prefer = 0;
2714 
2715         policy_cache = kmem_cache_create("numa_policy",
2716                                          sizeof(struct mempolicy),
2717                                          0, SLAB_PANIC, NULL);
2718 
2719         sn_cache = kmem_cache_create("shared_policy_node",
2720                                      sizeof(struct sp_node),
2721                                      0, SLAB_PANIC, NULL);
2722 
2723         for_each_node(nid) {
2724                 preferred_node_policy[nid] = (struct mempolicy) {
2725                         .refcnt = ATOMIC_INIT(1),
2726                         .mode = MPOL_PREFERRED,
2727                         .flags = MPOL_F_MOF | MPOL_F_MORON,
2728                         .v = { .preferred_node = nid, },
2729                 };
2730         }
2731 
2732         /*
2733          * Set interleaving policy for system init. Interleaving is only
2734          * enabled across suitably sized nodes (default is >= 16MB), or
2735          * fall back to the largest node if they're all smaller.
2736          */
2737         nodes_clear(interleave_nodes);
2738         for_each_node_state(nid, N_MEMORY) {
2739                 unsigned long total_pages = node_present_pages(nid);
2740 
2741                 /* Preserve the largest node */
2742                 if (largest < total_pages) {
2743                         largest = total_pages;
2744                         prefer = nid;
2745                 }
2746 
2747                 /* Interleave this node? */
2748                 if ((total_pages << PAGE_SHIFT) >= (16 << 20))
2749                         node_set(nid, interleave_nodes);
2750         }
2751 
2752         /* All too small, use the largest */
2753         if (unlikely(nodes_empty(interleave_nodes)))
2754                 node_set(prefer, interleave_nodes);
2755 
2756         if (do_set_mempolicy(MPOL_INTERLEAVE, 0, &interleave_nodes))
2757                 pr_err("%s: interleaving failed\n", __func__);
2758 
2759         check_numabalancing_enable();
2760 }
2761 
2762 /* Reset policy of current process to default */
2763 void numa_default_policy(void)
2764 {
2765         do_set_mempolicy(MPOL_DEFAULT, 0, NULL);
2766 }
2767 
2768 /*
2769  * Parse and format mempolicy from/to strings
2770  */
2771 
2772 /*
2773  * "local" is implemented internally by MPOL_PREFERRED with MPOL_F_LOCAL flag.
2774  */
2775 static const char * const policy_modes[] =
2776 {
2777         [MPOL_DEFAULT]    = "default",
2778         [MPOL_PREFERRED]  = "prefer",
2779         [MPOL_BIND]       = "bind",
2780         [MPOL_INTERLEAVE] = "interleave",
2781         [MPOL_LOCAL]      = "local",
2782 };
2783 
2784 
2785 #ifdef CONFIG_TMPFS
2786 /**
2787  * mpol_parse_str - parse string to mempolicy, for tmpfs mpol mount option.
2788  * @str:  string containing mempolicy to parse
2789  * @mpol:  pointer to struct mempolicy pointer, returned on success.
2790  *
2791  * Format of input:
2792  *      <mode>[=<flags>][:<nodelist>]
2793  *
2794  * On success, returns 0, else 1
2795  */
2796 int mpol_parse_str(char *str, struct mempolicy **mpol)
2797 {
2798         struct mempolicy *new = NULL;
2799         unsigned short mode_flags;
2800         nodemask_t nodes;
2801         char *nodelist = strchr(str, ':');
2802         char *flags = strchr(str, '=');
2803         int err = 1, mode;
2804 
2805         if (flags)
2806                 *flags++ = '\0';        /* terminate mode string */
2807 
2808         if (nodelist) {
2809                 /* NUL-terminate mode or flags string */
2810                 *nodelist++ = '\0';
2811                 if (nodelist_parse(nodelist, nodes))
2812                         goto out;
2813                 if (!nodes_subset(nodes, node_states[N_MEMORY]))
2814                         goto out;
2815         } else
2816                 nodes_clear(nodes);
2817 
2818         mode = match_string(policy_modes, MPOL_MAX, str);
2819         if (mode < 0)
2820                 goto out;
2821 
2822         switch (mode) {
2823         case MPOL_PREFERRED:
2824                 /*
2825                  * Insist on a nodelist of one node only, although later
2826                  * we use first_node(nodes) to grab a single node, so here
2827                  * nodelist (or nodes) cannot be empty.
2828                  */
2829                 if (nodelist) {
2830                         char *rest = nodelist;
2831                         while (isdigit(*rest))
2832                                 rest++;
2833                         if (*rest)
2834                                 goto out;
2835                         if (nodes_empty(nodes))
2836                                 goto out;
2837                 }
2838                 break;
2839         case MPOL_INTERLEAVE:
2840                 /*
2841                  * Default to online nodes with memory if no nodelist
2842                  */
2843                 if (!nodelist)
2844                         nodes = node_states[N_MEMORY];
2845                 break;
2846         case MPOL_LOCAL:
2847                 /*
2848                  * Don't allow a nodelist;  mpol_new() checks flags
2849                  */
2850                 if (nodelist)
2851                         goto out;
2852                 mode = MPOL_PREFERRED;
2853                 break;
2854         case MPOL_DEFAULT:
2855                 /*
2856                  * Insist on a empty nodelist
2857                  */
2858                 if (!nodelist)
2859                         err = 0;
2860                 goto out;
2861         case MPOL_BIND:
2862                 /*
2863                  * Insist on a nodelist
2864                  */
2865                 if (!nodelist)
2866                         goto out;
2867         }
2868 
2869         mode_flags = 0;
2870         if (flags) {
2871                 /*
2872                  * Currently, we only support two mutually exclusive
2873                  * mode flags.
2874                  */
2875                 if (!strcmp(flags, "static"))
2876                         mode_flags |= MPOL_F_STATIC_NODES;
2877                 else if (!strcmp(flags, "relative"))
2878                         mode_flags |= MPOL_F_RELATIVE_NODES;
2879                 else
2880                         goto out;
2881         }
2882 
2883         new = mpol_new(mode, mode_flags, &nodes);
2884         if (IS_ERR(new))
2885                 goto out;
2886 
2887         /*
2888          * Save nodes for mpol_to_str() to show the tmpfs mount options
2889          * for /proc/mounts, /proc/pid/mounts and /proc/pid/mountinfo.
2890          */
2891         if (mode != MPOL_PREFERRED)
2892                 new->v.nodes = nodes;
2893         else if (nodelist)
2894                 new->v.preferred_node = first_node(nodes);
2895         else
2896                 new->flags |= MPOL_F_LOCAL;
2897 
2898         /*
2899          * Save nodes for contextualization: this will be used to "clone"
2900          * the mempolicy in a specific context [cpuset] at a later time.
2901          */
2902         new->w.user_nodemask = nodes;
2903 
2904         err = 0;
2905 
2906 out:
2907         /* Restore string for error message */
2908         if (nodelist)
2909                 *--nodelist = ':';
2910         if (flags)
2911                 *--flags = '=';
2912         if (!err)
2913                 *mpol = new;
2914         return err;
2915 }
2916 #endif /* CONFIG_TMPFS */
2917 
2918 /**
2919  * mpol_to_str - format a mempolicy structure for printing
2920  * @buffer:  to contain formatted mempolicy string
2921  * @maxlen:  length of @buffer
2922  * @pol:  pointer to mempolicy to be formatted
2923  *
2924  * Convert @pol into a string.  If @buffer is too short, truncate the string.
2925  * Recommend a @maxlen of at least 32 for the longest mode, "interleave", the
2926  * longest flag, "relative", and to display at least a few node ids.
2927  */
2928 void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
2929 {
2930         char *p = buffer;
2931         nodemask_t nodes = NODE_MASK_NONE;
2932         unsigned short mode = MPOL_DEFAULT;
2933         unsigned short flags = 0;
2934 
2935         if (pol && pol != &default_policy && !(pol->flags & MPOL_F_MORON)) {
2936                 mode = pol->mode;
2937                 flags = pol->flags;
2938         }
2939 
2940         switch (mode) {
2941         case MPOL_DEFAULT:
2942                 break;
2943         case MPOL_PREFERRED:
2944                 if (flags & MPOL_F_LOCAL)
2945                         mode = MPOL_LOCAL;
2946                 else
2947                         node_set(pol->v.preferred_node, nodes);
2948                 break;
2949         case MPOL_BIND:
2950         case MPOL_INTERLEAVE:
2951                 nodes = pol->v.nodes;
2952                 break;
2953         default:
2954                 WARN_ON_ONCE(1);
2955                 snprintf(p, maxlen, "unknown");
2956                 return;
2957         }
2958 
2959         p += snprintf(p, maxlen, "%s", policy_modes[mode]);
2960 
2961         if (flags & MPOL_MODE_FLAGS) {
2962                 p += snprintf(p, buffer + maxlen - p, "=");
2963 
2964                 /*
2965                  * Currently, the only defined flags are mutually exclusive
2966                  */
2967                 if (flags & MPOL_F_STATIC_NODES)
2968                         p += snprintf(p, buffer + maxlen - p, "static");
2969                 else if (flags & MPOL_F_RELATIVE_NODES)
2970                         p += snprintf(p, buffer + maxlen - p, "relative");
2971         }
2972 
2973         if (!nodes_empty(nodes))
2974                 p += scnprintf(p, buffer + maxlen - p, ":%*pbl",
2975                                nodemask_pr_args(&nodes));
2976 }