linux/mm/mempolicy.c
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   1/*
   2 * Simple NUMA memory policy for the Linux kernel.
   3 *
   4 * Copyright 2003,2004 Andi Kleen, SuSE Labs.
   5 * (C) Copyright 2005 Christoph Lameter, Silicon Graphics, Inc.
   6 * Subject to the GNU Public License, version 2.
   7 *
   8 * NUMA policy allows the user to give hints in which node(s) memory should
   9 * be allocated.
  10 *
  11 * Support four policies per VMA and per process:
  12 *
  13 * The VMA policy has priority over the process policy for a page fault.
  14 *
  15 * interleave     Allocate memory interleaved over a set of nodes,
  16 *                with normal fallback if it fails.
  17 *                For VMA based allocations this interleaves based on the
  18 *                offset into the backing object or offset into the mapping
  19 *                for anonymous memory. For process policy an process counter
  20 *                is used.
  21 *
  22 * bind           Only allocate memory on a specific set of nodes,
  23 *                no fallback.
  24 *                FIXME: memory is allocated starting with the first node
  25 *                to the last. It would be better if bind would truly restrict
  26 *                the allocation to memory nodes instead
  27 *
  28 * preferred       Try a specific node first before normal fallback.
  29 *                As a special case node -1 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#include <linux/mempolicy.h>
  69#include <linux/mm.h>
  70#include <linux/highmem.h>
  71#include <linux/hugetlb.h>
  72#include <linux/kernel.h>
  73#include <linux/sched.h>
  74#include <linux/nodemask.h>
  75#include <linux/cpuset.h>
  76#include <linux/slab.h>
  77#include <linux/string.h>
  78#include <linux/export.h>
  79#include <linux/nsproxy.h>
  80#include <linux/interrupt.h>
  81#include <linux/init.h>
  82#include <linux/compat.h>
  83#include <linux/swap.h>
  84#include <linux/seq_file.h>
  85#include <linux/proc_fs.h>
  86#include <linux/migrate.h>
  87#include <linux/ksm.h>
  88#include <linux/rmap.h>
  89#include <linux/security.h>
  90#include <linux/syscalls.h>
  91#include <linux/ctype.h>
  92#include <linux/mm_inline.h>
  93
  94#include <asm/tlbflush.h>
  95#include <asm/uaccess.h>
  96#include <linux/random.h>
  97
  98#include "internal.h"
  99
 100/* Internal flags */
 101#define MPOL_MF_DISCONTIG_OK (MPOL_MF_INTERNAL << 0)    /* Skip checks for continuous vmas */
 102#define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1)          /* Invert check for nodemask */
 103
 104static struct kmem_cache *policy_cache;
 105static struct kmem_cache *sn_cache;
 106
 107/* Highest zone. An specific allocation for a zone below that is not
 108   policied. */
 109enum zone_type policy_zone = 0;
 110
 111/*
 112 * run-time system-wide default policy => local allocation
 113 */
 114static struct mempolicy default_policy = {
 115        .refcnt = ATOMIC_INIT(1), /* never free it */
 116        .mode = MPOL_PREFERRED,
 117        .flags = MPOL_F_LOCAL,
 118};
 119
 120static const struct mempolicy_operations {
 121        int (*create)(struct mempolicy *pol, const nodemask_t *nodes);
 122        /*
 123         * If read-side task has no lock to protect task->mempolicy, write-side
 124         * task will rebind the task->mempolicy by two step. The first step is
 125         * setting all the newly nodes, and the second step is cleaning all the
 126         * disallowed nodes. In this way, we can avoid finding no node to alloc
 127         * page.
 128         * If we have a lock to protect task->mempolicy in read-side, we do
 129         * rebind directly.
 130         *
 131         * step:
 132         *      MPOL_REBIND_ONCE - do rebind work at once
 133         *      MPOL_REBIND_STEP1 - set all the newly nodes
 134         *      MPOL_REBIND_STEP2 - clean all the disallowed nodes
 135         */
 136        void (*rebind)(struct mempolicy *pol, const nodemask_t *nodes,
 137                        enum mpol_rebind_step step);
 138} mpol_ops[MPOL_MAX];
 139
 140/* Check that the nodemask contains at least one populated zone */
 141static int is_valid_nodemask(const nodemask_t *nodemask)
 142{
 143        int nd, k;
 144
 145        for_each_node_mask(nd, *nodemask) {
 146                struct zone *z;
 147
 148                for (k = 0; k <= policy_zone; k++) {
 149                        z = &NODE_DATA(nd)->node_zones[k];
 150                        if (z->present_pages > 0)
 151                                return 1;
 152                }
 153        }
 154
 155        return 0;
 156}
 157
 158static inline int mpol_store_user_nodemask(const struct mempolicy *pol)
 159{
 160        return pol->flags & MPOL_MODE_FLAGS;
 161}
 162
 163static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,
 164                                   const nodemask_t *rel)
 165{
 166        nodemask_t tmp;
 167        nodes_fold(tmp, *orig, nodes_weight(*rel));
 168        nodes_onto(*ret, tmp, *rel);
 169}
 170
 171static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes)
 172{
 173        if (nodes_empty(*nodes))
 174                return -EINVAL;
 175        pol->v.nodes = *nodes;
 176        return 0;
 177}
 178
 179static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes)
 180{
 181        if (!nodes)
 182                pol->flags |= MPOL_F_LOCAL;     /* local allocation */
 183        else if (nodes_empty(*nodes))
 184                return -EINVAL;                 /*  no allowed nodes */
 185        else
 186                pol->v.preferred_node = first_node(*nodes);
 187        return 0;
 188}
 189
 190static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
 191{
 192        if (!is_valid_nodemask(nodes))
 193                return -EINVAL;
 194        pol->v.nodes = *nodes;
 195        return 0;
 196}
 197
 198/*
 199 * mpol_set_nodemask is called after mpol_new() to set up the nodemask, if
 200 * any, for the new policy.  mpol_new() has already validated the nodes
 201 * parameter with respect to the policy mode and flags.  But, we need to
 202 * handle an empty nodemask with MPOL_PREFERRED here.
 203 *
 204 * Must be called holding task's alloc_lock to protect task's mems_allowed
 205 * and mempolicy.  May also be called holding the mmap_semaphore for write.
 206 */
 207static int mpol_set_nodemask(struct mempolicy *pol,
 208                     const nodemask_t *nodes, struct nodemask_scratch *nsc)
 209{
 210        int ret;
 211
 212        /* if mode is MPOL_DEFAULT, pol is NULL. This is right. */
 213        if (pol == NULL)
 214                return 0;
 215        /* Check N_HIGH_MEMORY */
 216        nodes_and(nsc->mask1,
 217                  cpuset_current_mems_allowed, node_states[N_HIGH_MEMORY]);
 218
 219        VM_BUG_ON(!nodes);
 220        if (pol->mode == MPOL_PREFERRED && nodes_empty(*nodes))
 221                nodes = NULL;   /* explicit local allocation */
 222        else {
 223                if (pol->flags & MPOL_F_RELATIVE_NODES)
 224                        mpol_relative_nodemask(&nsc->mask2, nodes,&nsc->mask1);
 225                else
 226                        nodes_and(nsc->mask2, *nodes, nsc->mask1);
 227
 228                if (mpol_store_user_nodemask(pol))
 229                        pol->w.user_nodemask = *nodes;
 230                else
 231                        pol->w.cpuset_mems_allowed =
 232                                                cpuset_current_mems_allowed;
 233        }
 234
 235        if (nodes)
 236                ret = mpol_ops[pol->mode].create(pol, &nsc->mask2);
 237        else
 238                ret = mpol_ops[pol->mode].create(pol, NULL);
 239        return ret;
 240}
 241
 242/*
 243 * This function just creates a new policy, does some check and simple
 244 * initialization. You must invoke mpol_set_nodemask() to set nodes.
 245 */
 246static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
 247                                  nodemask_t *nodes)
 248{
 249        struct mempolicy *policy;
 250
 251        pr_debug("setting mode %d flags %d nodes[0] %lx\n",
 252                 mode, flags, nodes ? nodes_addr(*nodes)[0] : -1);
 253
 254        if (mode == MPOL_DEFAULT) {
 255                if (nodes && !nodes_empty(*nodes))
 256                        return ERR_PTR(-EINVAL);
 257                return NULL;    /* simply delete any existing policy */
 258        }
 259        VM_BUG_ON(!nodes);
 260
 261        /*
 262         * MPOL_PREFERRED cannot be used with MPOL_F_STATIC_NODES or
 263         * MPOL_F_RELATIVE_NODES if the nodemask is empty (local allocation).
 264         * All other modes require a valid pointer to a non-empty nodemask.
 265         */
 266        if (mode == MPOL_PREFERRED) {
 267                if (nodes_empty(*nodes)) {
 268                        if (((flags & MPOL_F_STATIC_NODES) ||
 269                             (flags & MPOL_F_RELATIVE_NODES)))
 270                                return ERR_PTR(-EINVAL);
 271                }
 272        } else if (nodes_empty(*nodes))
 273                return ERR_PTR(-EINVAL);
 274        policy = kmem_cache_alloc(policy_cache, GFP_KERNEL);
 275        if (!policy)
 276                return ERR_PTR(-ENOMEM);
 277        atomic_set(&policy->refcnt, 1);
 278        policy->mode = mode;
 279        policy->flags = flags;
 280
 281        return policy;
 282}
 283
 284/* Slow path of a mpol destructor. */
 285void __mpol_put(struct mempolicy *p)
 286{
 287        if (!atomic_dec_and_test(&p->refcnt))
 288                return;
 289        kmem_cache_free(policy_cache, p);
 290}
 291
 292static void mpol_rebind_default(struct mempolicy *pol, const nodemask_t *nodes,
 293                                enum mpol_rebind_step step)
 294{
 295}
 296
 297/*
 298 * step:
 299 *      MPOL_REBIND_ONCE  - do rebind work at once
 300 *      MPOL_REBIND_STEP1 - set all the newly nodes
 301 *      MPOL_REBIND_STEP2 - clean all the disallowed nodes
 302 */
 303static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes,
 304                                 enum mpol_rebind_step step)
 305{
 306        nodemask_t tmp;
 307
 308        if (pol->flags & MPOL_F_STATIC_NODES)
 309                nodes_and(tmp, pol->w.user_nodemask, *nodes);
 310        else if (pol->flags & MPOL_F_RELATIVE_NODES)
 311                mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
 312        else {
 313                /*
 314                 * if step == 1, we use ->w.cpuset_mems_allowed to cache the
 315                 * result
 316                 */
 317                if (step == MPOL_REBIND_ONCE || step == MPOL_REBIND_STEP1) {
 318                        nodes_remap(tmp, pol->v.nodes,
 319                                        pol->w.cpuset_mems_allowed, *nodes);
 320                        pol->w.cpuset_mems_allowed = step ? tmp : *nodes;
 321                } else if (step == MPOL_REBIND_STEP2) {
 322                        tmp = pol->w.cpuset_mems_allowed;
 323                        pol->w.cpuset_mems_allowed = *nodes;
 324                } else
 325                        BUG();
 326        }
 327
 328        if (nodes_empty(tmp))
 329                tmp = *nodes;
 330
 331        if (step == MPOL_REBIND_STEP1)
 332                nodes_or(pol->v.nodes, pol->v.nodes, tmp);
 333        else if (step == MPOL_REBIND_ONCE || step == MPOL_REBIND_STEP2)
 334                pol->v.nodes = tmp;
 335        else
 336                BUG();
 337
 338        if (!node_isset(current->il_next, tmp)) {
 339                current->il_next = next_node(current->il_next, tmp);
 340                if (current->il_next >= MAX_NUMNODES)
 341                        current->il_next = first_node(tmp);
 342                if (current->il_next >= MAX_NUMNODES)
 343                        current->il_next = numa_node_id();
 344        }
 345}
 346
 347static void mpol_rebind_preferred(struct mempolicy *pol,
 348                                  const nodemask_t *nodes,
 349                                  enum mpol_rebind_step step)
 350{
 351        nodemask_t tmp;
 352
 353        if (pol->flags & MPOL_F_STATIC_NODES) {
 354                int node = first_node(pol->w.user_nodemask);
 355
 356                if (node_isset(node, *nodes)) {
 357                        pol->v.preferred_node = node;
 358                        pol->flags &= ~MPOL_F_LOCAL;
 359                } else
 360                        pol->flags |= MPOL_F_LOCAL;
 361        } else if (pol->flags & MPOL_F_RELATIVE_NODES) {
 362                mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
 363                pol->v.preferred_node = first_node(tmp);
 364        } else if (!(pol->flags & MPOL_F_LOCAL)) {
 365                pol->v.preferred_node = node_remap(pol->v.preferred_node,
 366                                                   pol->w.cpuset_mems_allowed,
 367                                                   *nodes);
 368                pol->w.cpuset_mems_allowed = *nodes;
 369        }
 370}
 371
 372/*
 373 * mpol_rebind_policy - Migrate a policy to a different set of nodes
 374 *
 375 * If read-side task has no lock to protect task->mempolicy, write-side
 376 * task will rebind the task->mempolicy by two step. The first step is
 377 * setting all the newly nodes, and the second step is cleaning all the
 378 * disallowed nodes. In this way, we can avoid finding no node to alloc
 379 * page.
 380 * If we have a lock to protect task->mempolicy in read-side, we do
 381 * rebind directly.
 382 *
 383 * step:
 384 *      MPOL_REBIND_ONCE  - do rebind work at once
 385 *      MPOL_REBIND_STEP1 - set all the newly nodes
 386 *      MPOL_REBIND_STEP2 - clean all the disallowed nodes
 387 */
 388static void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *newmask,
 389                                enum mpol_rebind_step step)
 390{
 391        if (!pol)
 392                return;
 393        if (!mpol_store_user_nodemask(pol) && step == MPOL_REBIND_ONCE &&
 394            nodes_equal(pol->w.cpuset_mems_allowed, *newmask))
 395                return;
 396
 397        if (step == MPOL_REBIND_STEP1 && (pol->flags & MPOL_F_REBINDING))
 398                return;
 399
 400        if (step == MPOL_REBIND_STEP2 && !(pol->flags & MPOL_F_REBINDING))
 401                BUG();
 402
 403        if (step == MPOL_REBIND_STEP1)
 404                pol->flags |= MPOL_F_REBINDING;
 405        else if (step == MPOL_REBIND_STEP2)
 406                pol->flags &= ~MPOL_F_REBINDING;
 407        else if (step >= MPOL_REBIND_NSTEP)
 408                BUG();
 409
 410        mpol_ops[pol->mode].rebind(pol, newmask, step);
 411}
 412
 413/*
 414 * Wrapper for mpol_rebind_policy() that just requires task
 415 * pointer, and updates task mempolicy.
 416 *
 417 * Called with task's alloc_lock held.
 418 */
 419
 420void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new,
 421                        enum mpol_rebind_step step)
 422{
 423        mpol_rebind_policy(tsk->mempolicy, new, step);
 424}
 425
 426/*
 427 * Rebind each vma in mm to new nodemask.
 428 *
 429 * Call holding a reference to mm.  Takes mm->mmap_sem during call.
 430 */
 431
 432void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
 433{
 434        struct vm_area_struct *vma;
 435
 436        down_write(&mm->mmap_sem);
 437        for (vma = mm->mmap; vma; vma = vma->vm_next)
 438                mpol_rebind_policy(vma->vm_policy, new, MPOL_REBIND_ONCE);
 439        up_write(&mm->mmap_sem);
 440}
 441
 442static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
 443        [MPOL_DEFAULT] = {
 444                .rebind = mpol_rebind_default,
 445        },
 446        [MPOL_INTERLEAVE] = {
 447                .create = mpol_new_interleave,
 448                .rebind = mpol_rebind_nodemask,
 449        },
 450        [MPOL_PREFERRED] = {
 451                .create = mpol_new_preferred,
 452                .rebind = mpol_rebind_preferred,
 453        },
 454        [MPOL_BIND] = {
 455                .create = mpol_new_bind,
 456                .rebind = mpol_rebind_nodemask,
 457        },
 458};
 459
 460static void migrate_page_add(struct page *page, struct list_head *pagelist,
 461                                unsigned long flags);
 462
 463/* Scan through pages checking if pages follow certain conditions. */
 464static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
 465                unsigned long addr, unsigned long end,
 466                const nodemask_t *nodes, unsigned long flags,
 467                void *private)
 468{
 469        pte_t *orig_pte;
 470        pte_t *pte;
 471        spinlock_t *ptl;
 472
 473        orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 474        do {
 475                struct page *page;
 476                int nid;
 477
 478                if (!pte_present(*pte))
 479                        continue;
 480                page = vm_normal_page(vma, addr, *pte);
 481                if (!page)
 482                        continue;
 483                /*
 484                 * vm_normal_page() filters out zero pages, but there might
 485                 * still be PageReserved pages to skip, perhaps in a VDSO.
 486                 * And we cannot move PageKsm pages sensibly or safely yet.
 487                 */
 488                if (PageReserved(page) || PageKsm(page))
 489                        continue;
 490                nid = page_to_nid(page);
 491                if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
 492                        continue;
 493
 494                if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
 495                        migrate_page_add(page, private, flags);
 496                else
 497                        break;
 498        } while (pte++, addr += PAGE_SIZE, addr != end);
 499        pte_unmap_unlock(orig_pte, ptl);
 500        return addr != end;
 501}
 502
 503static inline int check_pmd_range(struct vm_area_struct *vma, pud_t *pud,
 504                unsigned long addr, unsigned long end,
 505                const nodemask_t *nodes, unsigned long flags,
 506                void *private)
 507{
 508        pmd_t *pmd;
 509        unsigned long next;
 510
 511        pmd = pmd_offset(pud, addr);
 512        do {
 513                next = pmd_addr_end(addr, end);
 514                split_huge_page_pmd(vma->vm_mm, pmd);
 515                if (pmd_none_or_trans_huge_or_clear_bad(pmd))
 516                        continue;
 517                if (check_pte_range(vma, pmd, addr, next, nodes,
 518                                    flags, private))
 519                        return -EIO;
 520        } while (pmd++, addr = next, addr != end);
 521        return 0;
 522}
 523
 524static inline int check_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
 525                unsigned long addr, unsigned long end,
 526                const nodemask_t *nodes, unsigned long flags,
 527                void *private)
 528{
 529        pud_t *pud;
 530        unsigned long next;
 531
 532        pud = pud_offset(pgd, addr);
 533        do {
 534                next = pud_addr_end(addr, end);
 535                if (pud_none_or_clear_bad(pud))
 536                        continue;
 537                if (check_pmd_range(vma, pud, addr, next, nodes,
 538                                    flags, private))
 539                        return -EIO;
 540        } while (pud++, addr = next, addr != end);
 541        return 0;
 542}
 543
 544static inline int check_pgd_range(struct vm_area_struct *vma,
 545                unsigned long addr, unsigned long end,
 546                const nodemask_t *nodes, unsigned long flags,
 547                void *private)
 548{
 549        pgd_t *pgd;
 550        unsigned long next;
 551
 552        pgd = pgd_offset(vma->vm_mm, addr);
 553        do {
 554                next = pgd_addr_end(addr, end);
 555                if (pgd_none_or_clear_bad(pgd))
 556                        continue;
 557                if (check_pud_range(vma, pgd, addr, next, nodes,
 558                                    flags, private))
 559                        return -EIO;
 560        } while (pgd++, addr = next, addr != end);
 561        return 0;
 562}
 563
 564/*
 565 * Check if all pages in a range are on a set of nodes.
 566 * If pagelist != NULL then isolate pages from the LRU and
 567 * put them on the pagelist.
 568 */
 569static struct vm_area_struct *
 570check_range(struct mm_struct *mm, unsigned long start, unsigned long end,
 571                const nodemask_t *nodes, unsigned long flags, void *private)
 572{
 573        int err;
 574        struct vm_area_struct *first, *vma, *prev;
 575
 576
 577        first = find_vma(mm, start);
 578        if (!first)
 579                return ERR_PTR(-EFAULT);
 580        prev = NULL;
 581        for (vma = first; vma && vma->vm_start < end; vma = vma->vm_next) {
 582                if (!(flags & MPOL_MF_DISCONTIG_OK)) {
 583                        if (!vma->vm_next && vma->vm_end < end)
 584                                return ERR_PTR(-EFAULT);
 585                        if (prev && prev->vm_end < vma->vm_start)
 586                                return ERR_PTR(-EFAULT);
 587                }
 588                if (!is_vm_hugetlb_page(vma) &&
 589                    ((flags & MPOL_MF_STRICT) ||
 590                     ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
 591                                vma_migratable(vma)))) {
 592                        unsigned long endvma = vma->vm_end;
 593
 594                        if (endvma > end)
 595                                endvma = end;
 596                        if (vma->vm_start > start)
 597                                start = vma->vm_start;
 598                        err = check_pgd_range(vma, start, endvma, nodes,
 599                                                flags, private);
 600                        if (err) {
 601                                first = ERR_PTR(err);
 602                                break;
 603                        }
 604                }
 605                prev = vma;
 606        }
 607        return first;
 608}
 609
 610/* Step 2: apply policy to a range and do splits. */
 611static int mbind_range(struct mm_struct *mm, unsigned long start,
 612                       unsigned long end, struct mempolicy *new_pol)
 613{
 614        struct vm_area_struct *next;
 615        struct vm_area_struct *prev;
 616        struct vm_area_struct *vma;
 617        int err = 0;
 618        pgoff_t pgoff;
 619        unsigned long vmstart;
 620        unsigned long vmend;
 621
 622        vma = find_vma(mm, start);
 623        if (!vma || vma->vm_start > start)
 624                return -EFAULT;
 625
 626        prev = vma->vm_prev;
 627        if (start > vma->vm_start)
 628                prev = vma;
 629
 630        for (; vma && vma->vm_start < end; prev = vma, vma = next) {
 631                next = vma->vm_next;
 632                vmstart = max(start, vma->vm_start);
 633                vmend   = min(end, vma->vm_end);
 634
 635                if (mpol_equal(vma_policy(vma), new_pol))
 636                        continue;
 637
 638                pgoff = vma->vm_pgoff +
 639                        ((vmstart - vma->vm_start) >> PAGE_SHIFT);
 640                prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
 641                                  vma->anon_vma, vma->vm_file, pgoff,
 642                                  new_pol);
 643                if (prev) {
 644                        vma = prev;
 645                        next = vma->vm_next;
 646                        continue;
 647                }
 648                if (vma->vm_start != vmstart) {
 649                        err = split_vma(vma->vm_mm, vma, vmstart, 1);
 650                        if (err)
 651                                goto out;
 652                }
 653                if (vma->vm_end != vmend) {
 654                        err = split_vma(vma->vm_mm, vma, vmend, 0);
 655                        if (err)
 656                                goto out;
 657                }
 658
 659                /*
 660                 * Apply policy to a single VMA. The reference counting of
 661                 * policy for vma_policy linkages has already been handled by
 662                 * vma_merge and split_vma as necessary. If this is a shared
 663                 * policy then ->set_policy will increment the reference count
 664                 * for an sp node.
 665                 */
 666                pr_debug("vma %lx-%lx/%lx vm_ops %p vm_file %p set_policy %p\n",
 667                        vma->vm_start, vma->vm_end, vma->vm_pgoff,
 668                        vma->vm_ops, vma->vm_file,
 669                        vma->vm_ops ? vma->vm_ops->set_policy : NULL);
 670                if (vma->vm_ops && vma->vm_ops->set_policy) {
 671                        err = vma->vm_ops->set_policy(vma, new_pol);
 672                        if (err)
 673                                goto out;
 674                }
 675        }
 676
 677 out:
 678        return err;
 679}
 680
 681/*
 682 * Update task->flags PF_MEMPOLICY bit: set iff non-default
 683 * mempolicy.  Allows more rapid checking of this (combined perhaps
 684 * with other PF_* flag bits) on memory allocation hot code paths.
 685 *
 686 * If called from outside this file, the task 'p' should -only- be
 687 * a newly forked child not yet visible on the task list, because
 688 * manipulating the task flags of a visible task is not safe.
 689 *
 690 * The above limitation is why this routine has the funny name
 691 * mpol_fix_fork_child_flag().
 692 *
 693 * It is also safe to call this with a task pointer of current,
 694 * which the static wrapper mpol_set_task_struct_flag() does,
 695 * for use within this file.
 696 */
 697
 698void mpol_fix_fork_child_flag(struct task_struct *p)
 699{
 700        if (p->mempolicy)
 701                p->flags |= PF_MEMPOLICY;
 702        else
 703                p->flags &= ~PF_MEMPOLICY;
 704}
 705
 706static void mpol_set_task_struct_flag(void)
 707{
 708        mpol_fix_fork_child_flag(current);
 709}
 710
 711/* Set the process memory policy */
 712static long do_set_mempolicy(unsigned short mode, unsigned short flags,
 713                             nodemask_t *nodes)
 714{
 715        struct mempolicy *new, *old;
 716        struct mm_struct *mm = current->mm;
 717        NODEMASK_SCRATCH(scratch);
 718        int ret;
 719
 720        if (!scratch)
 721                return -ENOMEM;
 722
 723        new = mpol_new(mode, flags, nodes);
 724        if (IS_ERR(new)) {
 725                ret = PTR_ERR(new);
 726                goto out;
 727        }
 728        /*
 729         * prevent changing our mempolicy while show_numa_maps()
 730         * is using it.
 731         * Note:  do_set_mempolicy() can be called at init time
 732         * with no 'mm'.
 733         */
 734        if (mm)
 735                down_write(&mm->mmap_sem);
 736        task_lock(current);
 737        ret = mpol_set_nodemask(new, nodes, scratch);
 738        if (ret) {
 739                task_unlock(current);
 740                if (mm)
 741                        up_write(&mm->mmap_sem);
 742                mpol_put(new);
 743                goto out;
 744        }
 745        old = current->mempolicy;
 746        current->mempolicy = new;
 747        mpol_set_task_struct_flag();
 748        if (new && new->mode == MPOL_INTERLEAVE &&
 749            nodes_weight(new->v.nodes))
 750                current->il_next = first_node(new->v.nodes);
 751        task_unlock(current);
 752        if (mm)
 753                up_write(&mm->mmap_sem);
 754
 755        mpol_put(old);
 756        ret = 0;
 757out:
 758        NODEMASK_SCRATCH_FREE(scratch);
 759        return ret;
 760}
 761
 762/*
 763 * Return nodemask for policy for get_mempolicy() query
 764 *
 765 * Called with task's alloc_lock held
 766 */
 767static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
 768{
 769        nodes_clear(*nodes);
 770        if (p == &default_policy)
 771                return;
 772
 773        switch (p->mode) {
 774        case MPOL_BIND:
 775                /* Fall through */
 776        case MPOL_INTERLEAVE:
 777                *nodes = p->v.nodes;
 778                break;
 779        case MPOL_PREFERRED:
 780                if (!(p->flags & MPOL_F_LOCAL))
 781                        node_set(p->v.preferred_node, *nodes);
 782                /* else return empty node mask for local allocation */
 783                break;
 784        default:
 785                BUG();
 786        }
 787}
 788
 789static int lookup_node(struct mm_struct *mm, unsigned long addr)
 790{
 791        struct page *p;
 792        int err;
 793
 794        err = get_user_pages(current, mm, addr & PAGE_MASK, 1, 0, 0, &p, NULL);
 795        if (err >= 0) {
 796                err = page_to_nid(p);
 797                put_page(p);
 798        }
 799        return err;
 800}
 801
 802/* Retrieve NUMA policy */
 803static long do_get_mempolicy(int *policy, nodemask_t *nmask,
 804                             unsigned long addr, unsigned long flags)
 805{
 806        int err;
 807        struct mm_struct *mm = current->mm;
 808        struct vm_area_struct *vma = NULL;
 809        struct mempolicy *pol = current->mempolicy;
 810
 811        if (flags &
 812                ~(unsigned long)(MPOL_F_NODE|MPOL_F_ADDR|MPOL_F_MEMS_ALLOWED))
 813                return -EINVAL;
 814
 815        if (flags & MPOL_F_MEMS_ALLOWED) {
 816                if (flags & (MPOL_F_NODE|MPOL_F_ADDR))
 817                        return -EINVAL;
 818                *policy = 0;    /* just so it's initialized */
 819                task_lock(current);
 820                *nmask  = cpuset_current_mems_allowed;
 821                task_unlock(current);
 822                return 0;
 823        }
 824
 825        if (flags & MPOL_F_ADDR) {
 826                /*
 827                 * Do NOT fall back to task policy if the
 828                 * vma/shared policy at addr is NULL.  We
 829                 * want to return MPOL_DEFAULT in this case.
 830                 */
 831                down_read(&mm->mmap_sem);
 832                vma = find_vma_intersection(mm, addr, addr+1);
 833                if (!vma) {
 834                        up_read(&mm->mmap_sem);
 835                        return -EFAULT;
 836                }
 837                if (vma->vm_ops && vma->vm_ops->get_policy)
 838                        pol = vma->vm_ops->get_policy(vma, addr);
 839                else
 840                        pol = vma->vm_policy;
 841        } else if (addr)
 842                return -EINVAL;
 843
 844        if (!pol)
 845                pol = &default_policy;  /* indicates default behavior */
 846
 847        if (flags & MPOL_F_NODE) {
 848                if (flags & MPOL_F_ADDR) {
 849                        err = lookup_node(mm, addr);
 850                        if (err < 0)
 851                                goto out;
 852                        *policy = err;
 853                } else if (pol == current->mempolicy &&
 854                                pol->mode == MPOL_INTERLEAVE) {
 855                        *policy = current->il_next;
 856                } else {
 857                        err = -EINVAL;
 858                        goto out;
 859                }
 860        } else {
 861                *policy = pol == &default_policy ? MPOL_DEFAULT :
 862                                                pol->mode;
 863                /*
 864                 * Internal mempolicy flags must be masked off before exposing
 865                 * the policy to userspace.
 866                 */
 867                *policy |= (pol->flags & MPOL_MODE_FLAGS);
 868        }
 869
 870        if (vma) {
 871                up_read(&current->mm->mmap_sem);
 872                vma = NULL;
 873        }
 874
 875        err = 0;
 876        if (nmask) {
 877                if (mpol_store_user_nodemask(pol)) {
 878                        *nmask = pol->w.user_nodemask;
 879                } else {
 880                        task_lock(current);
 881                        get_policy_nodemask(pol, nmask);
 882                        task_unlock(current);
 883                }
 884        }
 885
 886 out:
 887        mpol_cond_put(pol);
 888        if (vma)
 889                up_read(&current->mm->mmap_sem);
 890        return err;
 891}
 892
 893#ifdef CONFIG_MIGRATION
 894/*
 895 * page migration
 896 */
 897static void migrate_page_add(struct page *page, struct list_head *pagelist,
 898                                unsigned long flags)
 899{
 900        /*
 901         * Avoid migrating a page that is shared with others.
 902         */
 903        if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(page) == 1) {
 904                if (!isolate_lru_page(page)) {
 905                        list_add_tail(&page->lru, pagelist);
 906                        inc_zone_page_state(page, NR_ISOLATED_ANON +
 907                                            page_is_file_cache(page));
 908                }
 909        }
 910}
 911
 912static struct page *new_node_page(struct page *page, unsigned long node, int **x)
 913{
 914        return alloc_pages_exact_node(node, GFP_HIGHUSER_MOVABLE, 0);
 915}
 916
 917/*
 918 * Migrate pages from one node to a target node.
 919 * Returns error or the number of pages not migrated.
 920 */
 921static int migrate_to_node(struct mm_struct *mm, int source, int dest,
 922                           int flags)
 923{
 924        nodemask_t nmask;
 925        LIST_HEAD(pagelist);
 926        int err = 0;
 927        struct vm_area_struct *vma;
 928
 929        nodes_clear(nmask);
 930        node_set(source, nmask);
 931
 932        vma = check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
 933                        flags | MPOL_MF_DISCONTIG_OK, &pagelist);
 934        if (IS_ERR(vma))
 935                return PTR_ERR(vma);
 936
 937        if (!list_empty(&pagelist)) {
 938                err = migrate_pages(&pagelist, new_node_page, dest,
 939                                                        false, MIGRATE_SYNC);
 940                if (err)
 941                        putback_lru_pages(&pagelist);
 942        }
 943
 944        return err;
 945}
 946
 947/*
 948 * Move pages between the two nodesets so as to preserve the physical
 949 * layout as much as possible.
 950 *
 951 * Returns the number of page that could not be moved.
 952 */
 953int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
 954                     const nodemask_t *to, int flags)
 955{
 956        int busy = 0;
 957        int err;
 958        nodemask_t tmp;
 959
 960        err = migrate_prep();
 961        if (err)
 962                return err;
 963
 964        down_read(&mm->mmap_sem);
 965
 966        err = migrate_vmas(mm, from, to, flags);
 967        if (err)
 968                goto out;
 969
 970        /*
 971         * Find a 'source' bit set in 'tmp' whose corresponding 'dest'
 972         * bit in 'to' is not also set in 'tmp'.  Clear the found 'source'
 973         * bit in 'tmp', and return that <source, dest> pair for migration.
 974         * The pair of nodemasks 'to' and 'from' define the map.
 975         *
 976         * If no pair of bits is found that way, fallback to picking some
 977         * pair of 'source' and 'dest' bits that are not the same.  If the
 978         * 'source' and 'dest' bits are the same, this represents a node
 979         * that will be migrating to itself, so no pages need move.
 980         *
 981         * If no bits are left in 'tmp', or if all remaining bits left
 982         * in 'tmp' correspond to the same bit in 'to', return false
 983         * (nothing left to migrate).
 984         *
 985         * This lets us pick a pair of nodes to migrate between, such that
 986         * if possible the dest node is not already occupied by some other
 987         * source node, minimizing the risk of overloading the memory on a
 988         * node that would happen if we migrated incoming memory to a node
 989         * before migrating outgoing memory source that same node.
 990         *
 991         * A single scan of tmp is sufficient.  As we go, we remember the
 992         * most recent <s, d> pair that moved (s != d).  If we find a pair
 993         * that not only moved, but what's better, moved to an empty slot
 994         * (d is not set in tmp), then we break out then, with that pair.
 995         * Otherwise when we finish scanning from_tmp, we at least have the
 996         * most recent <s, d> pair that moved.  If we get all the way through
 997         * the scan of tmp without finding any node that moved, much less
 998         * moved to an empty node, then there is nothing left worth migrating.
 999         */
1000
1001        tmp = *from;
1002        while (!nodes_empty(tmp)) {
1003                int s,d;
1004                int source = -1;
1005                int dest = 0;
1006
1007                for_each_node_mask(s, tmp) {
1008
1009                        /*
1010                         * do_migrate_pages() tries to maintain the relative
1011                         * node relationship of the pages established between
1012                         * threads and memory areas.
1013                         *
1014                         * However if the number of source nodes is not equal to
1015                         * the number of destination nodes we can not preserve
1016                         * this node relative relationship.  In that case, skip
1017                         * copying memory from a node that is in the destination
1018                         * mask.
1019                         *
1020                         * Example: [2,3,4] -> [3,4,5] moves everything.
1021                         *          [0-7] - > [3,4,5] moves only 0,1,2,6,7.
1022                         */
1023
1024                        if ((nodes_weight(*from) != nodes_weight(*to)) &&
1025                                                (node_isset(s, *to)))
1026                                continue;
1027
1028                        d = node_remap(s, *from, *to);
1029                        if (s == d)
1030                                continue;
1031
1032                        source = s;     /* Node moved. Memorize */
1033                        dest = d;
1034
1035                        /* dest not in remaining from nodes? */
1036                        if (!node_isset(dest, tmp))
1037                                break;
1038                }
1039                if (source == -1)
1040                        break;
1041
1042                node_clear(source, tmp);
1043                err = migrate_to_node(mm, source, dest, flags);
1044                if (err > 0)
1045                        busy += err;
1046                if (err < 0)
1047                        break;
1048        }
1049out:
1050        up_read(&mm->mmap_sem);
1051        if (err < 0)
1052                return err;
1053        return busy;
1054
1055}
1056
1057/*
1058 * Allocate a new page for page migration based on vma policy.
1059 * Start assuming that page is mapped by vma pointed to by @private.
1060 * Search forward from there, if not.  N.B., this assumes that the
1061 * list of pages handed to migrate_pages()--which is how we get here--
1062 * is in virtual address order.
1063 */
1064static struct page *new_vma_page(struct page *page, unsigned long private, int **x)
1065{
1066        struct vm_area_struct *vma = (struct vm_area_struct *)private;
1067        unsigned long uninitialized_var(address);
1068
1069        while (vma) {
1070                address = page_address_in_vma(page, vma);
1071                if (address != -EFAULT)
1072                        break;
1073                vma = vma->vm_next;
1074        }
1075
1076        /*
1077         * if !vma, alloc_page_vma() will use task or system default policy
1078         */
1079        return alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
1080}
1081#else
1082
1083static void migrate_page_add(struct page *page, struct list_head *pagelist,
1084                                unsigned long flags)
1085{
1086}
1087
1088int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
1089                     const nodemask_t *to, int flags)
1090{
1091        return -ENOSYS;
1092}
1093
1094static struct page *new_vma_page(struct page *page, unsigned long private, int **x)
1095{
1096        return NULL;
1097}
1098#endif
1099
1100static long do_mbind(unsigned long start, unsigned long len,
1101                     unsigned short mode, unsigned short mode_flags,
1102                     nodemask_t *nmask, unsigned long flags)
1103{
1104        struct vm_area_struct *vma;
1105        struct mm_struct *mm = current->mm;
1106        struct mempolicy *new;
1107        unsigned long end;
1108        int err;
1109        LIST_HEAD(pagelist);
1110
1111        if (flags & ~(unsigned long)(MPOL_MF_STRICT |
1112                                     MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
1113                return -EINVAL;
1114        if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1115                return -EPERM;
1116
1117        if (start & ~PAGE_MASK)
1118                return -EINVAL;
1119
1120        if (mode == MPOL_DEFAULT)
1121                flags &= ~MPOL_MF_STRICT;
1122
1123        len = (len + PAGE_SIZE - 1) & PAGE_MASK;
1124        end = start + len;
1125
1126        if (end < start)
1127                return -EINVAL;
1128        if (end == start)
1129                return 0;
1130
1131        new = mpol_new(mode, mode_flags, nmask);
1132        if (IS_ERR(new))
1133                return PTR_ERR(new);
1134
1135        /*
1136         * If we are using the default policy then operation
1137         * on discontinuous address spaces is okay after all
1138         */
1139        if (!new)
1140                flags |= MPOL_MF_DISCONTIG_OK;
1141
1142        pr_debug("mbind %lx-%lx mode:%d flags:%d nodes:%lx\n",
1143                 start, start + len, mode, mode_flags,
1144                 nmask ? nodes_addr(*nmask)[0] : -1);
1145
1146        if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
1147
1148                err = migrate_prep();
1149                if (err)
1150                        goto mpol_out;
1151        }
1152        {
1153                NODEMASK_SCRATCH(scratch);
1154                if (scratch) {
1155                        down_write(&mm->mmap_sem);
1156                        task_lock(current);
1157                        err = mpol_set_nodemask(new, nmask, scratch);
1158                        task_unlock(current);
1159                        if (err)
1160                                up_write(&mm->mmap_sem);
1161                } else
1162                        err = -ENOMEM;
1163                NODEMASK_SCRATCH_FREE(scratch);
1164        }
1165        if (err)
1166                goto mpol_out;
1167
1168        vma = check_range(mm, start, end, nmask,
1169                          flags | MPOL_MF_INVERT, &pagelist);
1170
1171        err = PTR_ERR(vma);
1172        if (!IS_ERR(vma)) {
1173                int nr_failed = 0;
1174
1175                err = mbind_range(mm, start, end, new);
1176
1177                if (!list_empty(&pagelist)) {
1178                        nr_failed = migrate_pages(&pagelist, new_vma_page,
1179                                                (unsigned long)vma,
1180                                                false, MIGRATE_SYNC);
1181                        if (nr_failed)
1182                                putback_lru_pages(&pagelist);
1183                }
1184
1185                if (!err && nr_failed && (flags & MPOL_MF_STRICT))
1186                        err = -EIO;
1187        } else
1188                putback_lru_pages(&pagelist);
1189
1190        up_write(&mm->mmap_sem);
1191 mpol_out:
1192        mpol_put(new);
1193        return err;
1194}
1195
1196/*
1197 * User space interface with variable sized bitmaps for nodelists.
1198 */
1199
1200/* Copy a node mask from user space. */
1201static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask,
1202                     unsigned long maxnode)
1203{
1204        unsigned long k;
1205        unsigned long nlongs;
1206        unsigned long endmask;
1207
1208        --maxnode;
1209        nodes_clear(*nodes);
1210        if (maxnode == 0 || !nmask)
1211                return 0;
1212        if (maxnode > PAGE_SIZE*BITS_PER_BYTE)
1213                return -EINVAL;
1214
1215        nlongs = BITS_TO_LONGS(maxnode);
1216        if ((maxnode % BITS_PER_LONG) == 0)
1217                endmask = ~0UL;
1218        else
1219                endmask = (1UL << (maxnode % BITS_PER_LONG)) - 1;
1220
1221        /* When the user specified more nodes than supported just check
1222           if the non supported part is all zero. */
1223        if (nlongs > BITS_TO_LONGS(MAX_NUMNODES)) {
1224                if (nlongs > PAGE_SIZE/sizeof(long))
1225                        return -EINVAL;
1226                for (k = BITS_TO_LONGS(MAX_NUMNODES); k < nlongs; k++) {
1227                        unsigned long t;
1228                        if (get_user(t, nmask + k))
1229                                return -EFAULT;
1230                        if (k == nlongs - 1) {
1231                                if (t & endmask)
1232                                        return -EINVAL;
1233                        } else if (t)
1234                                return -EINVAL;
1235                }
1236                nlongs = BITS_TO_LONGS(MAX_NUMNODES);
1237                endmask = ~0UL;
1238        }
1239
1240        if (copy_from_user(nodes_addr(*nodes), nmask, nlongs*sizeof(unsigned long)))
1241                return -EFAULT;
1242        nodes_addr(*nodes)[nlongs-1] &= endmask;
1243        return 0;
1244}
1245
1246/* Copy a kernel node mask to user space */
1247static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
1248                              nodemask_t *nodes)
1249{
1250        unsigned long copy = ALIGN(maxnode-1, 64) / 8;
1251        const int nbytes = BITS_TO_LONGS(MAX_NUMNODES) * sizeof(long);
1252
1253        if (copy > nbytes) {
1254                if (copy > PAGE_SIZE)
1255                        return -EINVAL;
1256                if (clear_user((char __user *)mask + nbytes, copy - nbytes))
1257                        return -EFAULT;
1258                copy = nbytes;
1259        }
1260        return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0;
1261}
1262
1263SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
1264                unsigned long, mode, unsigned long __user *, nmask,
1265                unsigned long, maxnode, unsigned, flags)
1266{
1267        nodemask_t nodes;
1268        int err;
1269        unsigned short mode_flags;
1270
1271        mode_flags = mode & MPOL_MODE_FLAGS;
1272        mode &= ~MPOL_MODE_FLAGS;
1273        if (mode >= MPOL_MAX)
1274                return -EINVAL;
1275        if ((mode_flags & MPOL_F_STATIC_NODES) &&
1276            (mode_flags & MPOL_F_RELATIVE_NODES))
1277                return -EINVAL;
1278        err = get_nodes(&nodes, nmask, maxnode);
1279        if (err)
1280                return err;
1281        return do_mbind(start, len, mode, mode_flags, &nodes, flags);
1282}
1283
1284/* Set the process memory policy */
1285SYSCALL_DEFINE3(set_mempolicy, int, mode, unsigned long __user *, nmask,
1286                unsigned long, maxnode)
1287{
1288        int err;
1289        nodemask_t nodes;
1290        unsigned short flags;
1291
1292        flags = mode & MPOL_MODE_FLAGS;
1293        mode &= ~MPOL_MODE_FLAGS;
1294        if ((unsigned int)mode >= MPOL_MAX)
1295                return -EINVAL;
1296        if ((flags & MPOL_F_STATIC_NODES) && (flags & MPOL_F_RELATIVE_NODES))
1297                return -EINVAL;
1298        err = get_nodes(&nodes, nmask, maxnode);
1299        if (err)
1300                return err;
1301        return do_set_mempolicy(mode, flags, &nodes);
1302}
1303
1304SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
1305                const unsigned long __user *, old_nodes,
1306                const unsigned long __user *, new_nodes)
1307{
1308        const struct cred *cred = current_cred(), *tcred;
1309        struct mm_struct *mm = NULL;
1310        struct task_struct *task;
1311        nodemask_t task_nodes;
1312        int err;
1313        nodemask_t *old;
1314        nodemask_t *new;
1315        NODEMASK_SCRATCH(scratch);
1316
1317        if (!scratch)
1318                return -ENOMEM;
1319
1320        old = &scratch->mask1;
1321        new = &scratch->mask2;
1322
1323        err = get_nodes(old, old_nodes, maxnode);
1324        if (err)
1325                goto out;
1326
1327        err = get_nodes(new, new_nodes, maxnode);
1328        if (err)
1329                goto out;
1330
1331        /* Find the mm_struct */
1332        rcu_read_lock();
1333        task = pid ? find_task_by_vpid(pid) : current;
1334        if (!task) {
1335                rcu_read_unlock();
1336                err = -ESRCH;
1337                goto out;
1338        }
1339        get_task_struct(task);
1340
1341        err = -EINVAL;
1342
1343        /*
1344         * Check if this process has the right to modify the specified
1345         * process. The right exists if the process has administrative
1346         * capabilities, superuser privileges or the same
1347         * userid as the target process.
1348         */
1349        tcred = __task_cred(task);
1350        if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) &&
1351            !uid_eq(cred->uid,  tcred->suid) && !uid_eq(cred->uid,  tcred->uid) &&
1352            !capable(CAP_SYS_NICE)) {
1353                rcu_read_unlock();
1354                err = -EPERM;
1355                goto out_put;
1356        }
1357        rcu_read_unlock();
1358
1359        task_nodes = cpuset_mems_allowed(task);
1360        /* Is the user allowed to access the target nodes? */
1361        if (!nodes_subset(*new, task_nodes) && !capable(CAP_SYS_NICE)) {
1362                err = -EPERM;
1363                goto out_put;
1364        }
1365
1366        if (!nodes_subset(*new, node_states[N_HIGH_MEMORY])) {
1367                err = -EINVAL;
1368                goto out_put;
1369        }
1370
1371        err = security_task_movememory(task);
1372        if (err)
1373                goto out_put;
1374
1375        mm = get_task_mm(task);
1376        put_task_struct(task);
1377
1378        if (!mm) {
1379                err = -EINVAL;
1380                goto out;
1381        }
1382
1383        err = do_migrate_pages(mm, old, new,
1384                capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
1385
1386        mmput(mm);
1387out:
1388        NODEMASK_SCRATCH_FREE(scratch);
1389
1390        return err;
1391
1392out_put:
1393        put_task_struct(task);
1394        goto out;
1395
1396}
1397
1398
1399/* Retrieve NUMA policy */
1400SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
1401                unsigned long __user *, nmask, unsigned long, maxnode,
1402                unsigned long, addr, unsigned long, flags)
1403{
1404        int err;
1405        int uninitialized_var(pval);
1406        nodemask_t nodes;
1407
1408        if (nmask != NULL && maxnode < MAX_NUMNODES)
1409                return -EINVAL;
1410
1411        err = do_get_mempolicy(&pval, &nodes, addr, flags);
1412
1413        if (err)
1414                return err;
1415
1416        if (policy && put_user(pval, policy))
1417                return -EFAULT;
1418
1419        if (nmask)
1420                err = copy_nodes_to_user(nmask, maxnode, &nodes);
1421
1422        return err;
1423}
1424
1425#ifdef CONFIG_COMPAT
1426
1427asmlinkage long compat_sys_get_mempolicy(int __user *policy,
1428                                     compat_ulong_t __user *nmask,
1429                                     compat_ulong_t maxnode,
1430                                     compat_ulong_t addr, compat_ulong_t flags)
1431{
1432        long err;
1433        unsigned long __user *nm = NULL;
1434        unsigned long nr_bits, alloc_size;
1435        DECLARE_BITMAP(bm, MAX_NUMNODES);
1436
1437        nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
1438        alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1439
1440        if (nmask)
1441                nm = compat_alloc_user_space(alloc_size);
1442
1443        err = sys_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
1444
1445        if (!err && nmask) {
1446                unsigned long copy_size;
1447                copy_size = min_t(unsigned long, sizeof(bm), alloc_size);
1448                err = copy_from_user(bm, nm, copy_size);
1449                /* ensure entire bitmap is zeroed */
1450                err |= clear_user(nmask, ALIGN(maxnode-1, 8) / 8);
1451                err |= compat_put_bitmap(nmask, bm, nr_bits);
1452        }
1453
1454        return err;
1455}
1456
1457asmlinkage long compat_sys_set_mempolicy(int mode, compat_ulong_t __user *nmask,
1458                                     compat_ulong_t maxnode)
1459{
1460        long err = 0;
1461        unsigned long __user *nm = NULL;
1462        unsigned long nr_bits, alloc_size;
1463        DECLARE_BITMAP(bm, MAX_NUMNODES);
1464
1465        nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
1466        alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1467
1468        if (nmask) {
1469                err = compat_get_bitmap(bm, nmask, nr_bits);
1470                nm = compat_alloc_user_space(alloc_size);
1471                err |= copy_to_user(nm, bm, alloc_size);
1472        }
1473
1474        if (err)
1475                return -EFAULT;
1476
1477        return sys_set_mempolicy(mode, nm, nr_bits+1);
1478}
1479
1480asmlinkage long compat_sys_mbind(compat_ulong_t start, compat_ulong_t len,
1481                             compat_ulong_t mode, compat_ulong_t __user *nmask,
1482                             compat_ulong_t maxnode, compat_ulong_t flags)
1483{
1484        long err = 0;
1485        unsigned long __user *nm = NULL;
1486        unsigned long nr_bits, alloc_size;
1487        nodemask_t bm;
1488
1489        nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES);
1490        alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
1491
1492        if (nmask) {
1493                err = compat_get_bitmap(nodes_addr(bm), nmask, nr_bits);
1494                nm = compat_alloc_user_space(alloc_size);
1495                err |= copy_to_user(nm, nodes_addr(bm), alloc_size);
1496        }
1497
1498        if (err)
1499                return -EFAULT;
1500
1501        return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
1502}
1503
1504#endif
1505
1506/*
1507 * get_vma_policy(@task, @vma, @addr)
1508 * @task - task for fallback if vma policy == default
1509 * @vma   - virtual memory area whose policy is sought
1510 * @addr  - address in @vma for shared policy lookup
1511 *
1512 * Returns effective policy for a VMA at specified address.
1513 * Falls back to @task or system default policy, as necessary.
1514 * Current or other task's task mempolicy and non-shared vma policies
1515 * are protected by the task's mmap_sem, which must be held for read by
1516 * the caller.
1517 * Shared policies [those marked as MPOL_F_SHARED] require an extra reference
1518 * count--added by the get_policy() vm_op, as appropriate--to protect against
1519 * freeing by another task.  It is the caller's responsibility to free the
1520 * extra reference for shared policies.
1521 */
1522struct mempolicy *get_vma_policy(struct task_struct *task,
1523                struct vm_area_struct *vma, unsigned long addr)
1524{
1525        struct mempolicy *pol = task->mempolicy;
1526
1527        if (vma) {
1528                if (vma->vm_ops && vma->vm_ops->get_policy) {
1529                        struct mempolicy *vpol = vma->vm_ops->get_policy(vma,
1530                                                                        addr);
1531                        if (vpol)
1532                                pol = vpol;
1533                } else if (vma->vm_policy)
1534                        pol = vma->vm_policy;
1535        }
1536        if (!pol)
1537                pol = &default_policy;
1538        return pol;
1539}
1540
1541/*
1542 * Return a nodemask representing a mempolicy for filtering nodes for
1543 * page allocation
1544 */
1545static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
1546{
1547        /* Lower zones don't get a nodemask applied for MPOL_BIND */
1548        if (unlikely(policy->mode == MPOL_BIND) &&
1549                        gfp_zone(gfp) >= policy_zone &&
1550                        cpuset_nodemask_valid_mems_allowed(&policy->v.nodes))
1551                return &policy->v.nodes;
1552
1553        return NULL;
1554}
1555
1556/* Return a zonelist indicated by gfp for node representing a mempolicy */
1557static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy,
1558        int nd)
1559{
1560        switch (policy->mode) {
1561        case MPOL_PREFERRED:
1562                if (!(policy->flags & MPOL_F_LOCAL))
1563                        nd = policy->v.preferred_node;
1564                break;
1565        case MPOL_BIND:
1566                /*
1567                 * Normally, MPOL_BIND allocations are node-local within the
1568                 * allowed nodemask.  However, if __GFP_THISNODE is set and the
1569                 * current node isn't part of the mask, we use the zonelist for
1570                 * the first node in the mask instead.
1571                 */
1572                if (unlikely(gfp & __GFP_THISNODE) &&
1573                                unlikely(!node_isset(nd, policy->v.nodes)))
1574                        nd = first_node(policy->v.nodes);
1575                break;
1576        default:
1577                BUG();
1578        }
1579        return node_zonelist(nd, gfp);
1580}
1581
1582/* Do dynamic interleaving for a process */
1583static unsigned interleave_nodes(struct mempolicy *policy)
1584{
1585        unsigned nid, next;
1586        struct task_struct *me = current;
1587
1588        nid = me->il_next;
1589        next = next_node(nid, policy->v.nodes);
1590        if (next >= MAX_NUMNODES)
1591                next = first_node(policy->v.nodes);
1592        if (next < MAX_NUMNODES)
1593                me->il_next = next;
1594        return nid;
1595}
1596
1597/*
1598 * Depending on the memory policy provide a node from which to allocate the
1599 * next slab entry.
1600 * @policy must be protected by freeing by the caller.  If @policy is
1601 * the current task's mempolicy, this protection is implicit, as only the
1602 * task can change it's policy.  The system default policy requires no
1603 * such protection.
1604 */
1605unsigned slab_node(void)
1606{
1607        struct mempolicy *policy;
1608
1609        if (in_interrupt())
1610                return numa_node_id();
1611
1612        policy = current->mempolicy;
1613        if (!policy || policy->flags & MPOL_F_LOCAL)
1614                return numa_node_id();
1615
1616        switch (policy->mode) {
1617        case MPOL_PREFERRED:
1618                /*
1619                 * handled MPOL_F_LOCAL above
1620                 */
1621                return policy->v.preferred_node;
1622
1623        case MPOL_INTERLEAVE:
1624                return interleave_nodes(policy);
1625
1626        case MPOL_BIND: {
1627                /*
1628                 * Follow bind policy behavior and start allocation at the
1629                 * first node.
1630                 */
1631                struct zonelist *zonelist;
1632                struct zone *zone;
1633                enum zone_type highest_zoneidx = gfp_zone(GFP_KERNEL);
1634                zonelist = &NODE_DATA(numa_node_id())->node_zonelists[0];
1635                (void)first_zones_zonelist(zonelist, highest_zoneidx,
1636                                                        &policy->v.nodes,
1637                                                        &zone);
1638                return zone ? zone->node : numa_node_id();
1639        }
1640
1641        default:
1642                BUG();
1643        }
1644}
1645
1646/* Do static interleaving for a VMA with known offset. */
1647static unsigned offset_il_node(struct mempolicy *pol,
1648                struct vm_area_struct *vma, unsigned long off)
1649{
1650        unsigned nnodes = nodes_weight(pol->v.nodes);
1651        unsigned target;
1652        int c;
1653        int nid = -1;
1654
1655        if (!nnodes)
1656                return numa_node_id();
1657        target = (unsigned int)off % nnodes;
1658        c = 0;
1659        do {
1660                nid = next_node(nid, pol->v.nodes);
1661                c++;
1662        } while (c <= target);
1663        return nid;
1664}
1665
1666/* Determine a node number for interleave */
1667static inline unsigned interleave_nid(struct mempolicy *pol,
1668                 struct vm_area_struct *vma, unsigned long addr, int shift)
1669{
1670        if (vma) {
1671                unsigned long off;
1672
1673                /*
1674                 * for small pages, there is no difference between
1675                 * shift and PAGE_SHIFT, so the bit-shift is safe.
1676                 * for huge pages, since vm_pgoff is in units of small
1677                 * pages, we need to shift off the always 0 bits to get
1678                 * a useful offset.
1679                 */
1680                BUG_ON(shift < PAGE_SHIFT);
1681                off = vma->vm_pgoff >> (shift - PAGE_SHIFT);
1682                off += (addr - vma->vm_start) >> shift;
1683                return offset_il_node(pol, vma, off);
1684        } else
1685                return interleave_nodes(pol);
1686}
1687
1688/*
1689 * Return the bit number of a random bit set in the nodemask.
1690 * (returns -1 if nodemask is empty)
1691 */
1692int node_random(const nodemask_t *maskp)
1693{
1694        int w, bit = -1;
1695
1696        w = nodes_weight(*maskp);
1697        if (w)
1698                bit = bitmap_ord_to_pos(maskp->bits,
1699                        get_random_int() % w, MAX_NUMNODES);
1700        return bit;
1701}
1702
1703#ifdef CONFIG_HUGETLBFS
1704/*
1705 * huge_zonelist(@vma, @addr, @gfp_flags, @mpol)
1706 * @vma = virtual memory area whose policy is sought
1707 * @addr = address in @vma for shared policy lookup and interleave policy
1708 * @gfp_flags = for requested zone
1709 * @mpol = pointer to mempolicy pointer for reference counted mempolicy
1710 * @nodemask = pointer to nodemask pointer for MPOL_BIND nodemask
1711 *
1712 * Returns a zonelist suitable for a huge page allocation and a pointer
1713 * to the struct mempolicy for conditional unref after allocation.
1714 * If the effective policy is 'BIND, returns a pointer to the mempolicy's
1715 * @nodemask for filtering the zonelist.
1716 *
1717 * Must be protected by get_mems_allowed()
1718 */
1719struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
1720                                gfp_t gfp_flags, struct mempolicy **mpol,
1721                                nodemask_t **nodemask)
1722{
1723        struct zonelist *zl;
1724
1725        *mpol = get_vma_policy(current, vma, addr);
1726        *nodemask = NULL;       /* assume !MPOL_BIND */
1727
1728        if (unlikely((*mpol)->mode == MPOL_INTERLEAVE)) {
1729                zl = node_zonelist(interleave_nid(*mpol, vma, addr,
1730                                huge_page_shift(hstate_vma(vma))), gfp_flags);
1731        } else {
1732                zl = policy_zonelist(gfp_flags, *mpol, numa_node_id());
1733                if ((*mpol)->mode == MPOL_BIND)
1734                        *nodemask = &(*mpol)->v.nodes;
1735        }
1736        return zl;
1737}
1738
1739/*
1740 * init_nodemask_of_mempolicy
1741 *
1742 * If the current task's mempolicy is "default" [NULL], return 'false'
1743 * to indicate default policy.  Otherwise, extract the policy nodemask
1744 * for 'bind' or 'interleave' policy into the argument nodemask, or
1745 * initialize the argument nodemask to contain the single node for
1746 * 'preferred' or 'local' policy and return 'true' to indicate presence
1747 * of non-default mempolicy.
1748 *
1749 * We don't bother with reference counting the mempolicy [mpol_get/put]
1750 * because the current task is examining it's own mempolicy and a task's
1751 * mempolicy is only ever changed by the task itself.
1752 *
1753 * N.B., it is the caller's responsibility to free a returned nodemask.
1754 */
1755bool init_nodemask_of_mempolicy(nodemask_t *mask)
1756{
1757        struct mempolicy *mempolicy;
1758        int nid;
1759
1760        if (!(mask && current->mempolicy))
1761                return false;
1762
1763        task_lock(current);
1764        mempolicy = current->mempolicy;
1765        switch (mempolicy->mode) {
1766        case MPOL_PREFERRED:
1767                if (mempolicy->flags & MPOL_F_LOCAL)
1768                        nid = numa_node_id();
1769                else
1770                        nid = mempolicy->v.preferred_node;
1771                init_nodemask_of_node(mask, nid);
1772                break;
1773
1774        case MPOL_BIND:
1775                /* Fall through */
1776        case MPOL_INTERLEAVE:
1777                *mask =  mempolicy->v.nodes;
1778                break;
1779
1780        default:
1781                BUG();
1782        }
1783        task_unlock(current);
1784
1785        return true;
1786}
1787#endif
1788
1789/*
1790 * mempolicy_nodemask_intersects
1791 *
1792 * If tsk's mempolicy is "default" [NULL], return 'true' to indicate default
1793 * policy.  Otherwise, check for intersection between mask and the policy
1794 * nodemask for 'bind' or 'interleave' policy.  For 'perferred' or 'local'
1795 * policy, always return true since it may allocate elsewhere on fallback.
1796 *
1797 * Takes task_lock(tsk) to prevent freeing of its mempolicy.
1798 */
1799bool mempolicy_nodemask_intersects(struct task_struct *tsk,
1800                                        const nodemask_t *mask)
1801{
1802        struct mempolicy *mempolicy;
1803        bool ret = true;
1804
1805        if (!mask)
1806                return ret;
1807        task_lock(tsk);
1808        mempolicy = tsk->mempolicy;
1809        if (!mempolicy)
1810                goto out;
1811
1812        switch (mempolicy->mode) {
1813        case MPOL_PREFERRED:
1814                /*
1815                 * MPOL_PREFERRED and MPOL_F_LOCAL are only preferred nodes to
1816                 * allocate from, they may fallback to other nodes when oom.
1817                 * Thus, it's possible for tsk to have allocated memory from
1818                 * nodes in mask.
1819                 */
1820                break;
1821        case MPOL_BIND:
1822        case MPOL_INTERLEAVE:
1823                ret = nodes_intersects(mempolicy->v.nodes, *mask);
1824                break;
1825        default:
1826                BUG();
1827        }
1828out:
1829        task_unlock(tsk);
1830        return ret;
1831}
1832
1833/* Allocate a page in interleaved policy.
1834   Own path because it needs to do special accounting. */
1835static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
1836                                        unsigned nid)
1837{
1838        struct zonelist *zl;
1839        struct page *page;
1840
1841        zl = node_zonelist(nid, gfp);
1842        page = __alloc_pages(gfp, order, zl);
1843        if (page && page_zone(page) == zonelist_zone(&zl->_zonerefs[0]))
1844                inc_zone_page_state(page, NUMA_INTERLEAVE_HIT);
1845        return page;
1846}
1847
1848/**
1849 *      alloc_pages_vma - Allocate a page for a VMA.
1850 *
1851 *      @gfp:
1852 *      %GFP_USER    user allocation.
1853 *      %GFP_KERNEL  kernel allocations,
1854 *      %GFP_HIGHMEM highmem/user allocations,
1855 *      %GFP_FS      allocation should not call back into a file system.
1856 *      %GFP_ATOMIC  don't sleep.
1857 *
1858 *      @order:Order of the GFP allocation.
1859 *      @vma:  Pointer to VMA or NULL if not available.
1860 *      @addr: Virtual Address of the allocation. Must be inside the VMA.
1861 *
1862 *      This function allocates a page from the kernel page pool and applies
1863 *      a NUMA policy associated with the VMA or the current process.
1864 *      When VMA is not NULL caller must hold down_read on the mmap_sem of the
1865 *      mm_struct of the VMA to prevent it from going away. Should be used for
1866 *      all allocations for pages that will be mapped into
1867 *      user space. Returns NULL when no page can be allocated.
1868 *
1869 *      Should be called with the mm_sem of the vma hold.
1870 */
1871struct page *
1872alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
1873                unsigned long addr, int node)
1874{
1875        struct mempolicy *pol;
1876        struct zonelist *zl;
1877        struct page *page;
1878        unsigned int cpuset_mems_cookie;
1879
1880retry_cpuset:
1881        pol = get_vma_policy(current, vma, addr);
1882        cpuset_mems_cookie = get_mems_allowed();
1883
1884        if (unlikely(pol->mode == MPOL_INTERLEAVE)) {
1885                unsigned nid;
1886
1887                nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
1888                mpol_cond_put(pol);
1889                page = alloc_page_interleave(gfp, order, nid);
1890                if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
1891                        goto retry_cpuset;
1892
1893                return page;
1894        }
1895        zl = policy_zonelist(gfp, pol, node);
1896        if (unlikely(mpol_needs_cond_ref(pol))) {
1897                /*
1898                 * slow path: ref counted shared policy
1899                 */
1900                struct page *page =  __alloc_pages_nodemask(gfp, order,
1901                                                zl, policy_nodemask(gfp, pol));
1902                __mpol_put(pol);
1903                if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
1904                        goto retry_cpuset;
1905                return page;
1906        }
1907        /*
1908         * fast path:  default or task policy
1909         */
1910        page = __alloc_pages_nodemask(gfp, order, zl,
1911                                      policy_nodemask(gfp, pol));
1912        if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
1913                goto retry_cpuset;
1914        return page;
1915}
1916
1917/**
1918 *      alloc_pages_current - Allocate pages.
1919 *
1920 *      @gfp:
1921 *              %GFP_USER   user allocation,
1922 *              %GFP_KERNEL kernel allocation,
1923 *              %GFP_HIGHMEM highmem allocation,
1924 *              %GFP_FS     don't call back into a file system.
1925 *              %GFP_ATOMIC don't sleep.
1926 *      @order: Power of two of allocation size in pages. 0 is a single page.
1927 *
1928 *      Allocate a page from the kernel page pool.  When not in
1929 *      interrupt context and apply the current process NUMA policy.
1930 *      Returns NULL when no page can be allocated.
1931 *
1932 *      Don't call cpuset_update_task_memory_state() unless
1933 *      1) it's ok to take cpuset_sem (can WAIT), and
1934 *      2) allocating for current task (not interrupt).
1935 */
1936struct page *alloc_pages_current(gfp_t gfp, unsigned order)
1937{
1938        struct mempolicy *pol = current->mempolicy;
1939        struct page *page;
1940        unsigned int cpuset_mems_cookie;
1941
1942        if (!pol || in_interrupt() || (gfp & __GFP_THISNODE))
1943                pol = &default_policy;
1944
1945retry_cpuset:
1946        cpuset_mems_cookie = get_mems_allowed();
1947
1948        /*
1949         * No reference counting needed for current->mempolicy
1950         * nor system default_policy
1951         */
1952        if (pol->mode == MPOL_INTERLEAVE)
1953                page = alloc_page_interleave(gfp, order, interleave_nodes(pol));
1954        else
1955                page = __alloc_pages_nodemask(gfp, order,
1956                                policy_zonelist(gfp, pol, numa_node_id()),
1957                                policy_nodemask(gfp, pol));
1958
1959        if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
1960                goto retry_cpuset;
1961
1962        return page;
1963}
1964EXPORT_SYMBOL(alloc_pages_current);
1965
1966/*
1967 * If mpol_dup() sees current->cpuset == cpuset_being_rebound, then it
1968 * rebinds the mempolicy its copying by calling mpol_rebind_policy()
1969 * with the mems_allowed returned by cpuset_mems_allowed().  This
1970 * keeps mempolicies cpuset relative after its cpuset moves.  See
1971 * further kernel/cpuset.c update_nodemask().
1972 *
1973 * current's mempolicy may be rebinded by the other task(the task that changes
1974 * cpuset's mems), so we needn't do rebind work for current task.
1975 */
1976
1977/* Slow path of a mempolicy duplicate */
1978struct mempolicy *__mpol_dup(struct mempolicy *old)
1979{
1980        struct mempolicy *new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
1981
1982        if (!new)
1983                return ERR_PTR(-ENOMEM);
1984
1985        /* task's mempolicy is protected by alloc_lock */
1986        if (old == current->mempolicy) {
1987                task_lock(current);
1988                *new = *old;
1989                task_unlock(current);
1990        } else
1991                *new = *old;
1992
1993        rcu_read_lock();
1994        if (current_cpuset_is_being_rebound()) {
1995                nodemask_t mems = cpuset_mems_allowed(current);
1996                if (new->flags & MPOL_F_REBINDING)
1997                        mpol_rebind_policy(new, &mems, MPOL_REBIND_STEP2);
1998                else
1999                        mpol_rebind_policy(new, &mems, MPOL_REBIND_ONCE);
2000        }
2001        rcu_read_unlock();
2002        atomic_set(&new->refcnt, 1);
2003        return new;
2004}
2005
2006/*
2007 * If *frompol needs [has] an extra ref, copy *frompol to *tompol ,
2008 * eliminate the * MPOL_F_* flags that require conditional ref and
2009 * [NOTE!!!] drop the extra ref.  Not safe to reference *frompol directly
2010 * after return.  Use the returned value.
2011 *
2012 * Allows use of a mempolicy for, e.g., multiple allocations with a single
2013 * policy lookup, even if the policy needs/has extra ref on lookup.
2014 * shmem_readahead needs this.
2015 */
2016struct mempolicy *__mpol_cond_copy(struct mempolicy *tompol,
2017                                                struct mempolicy *frompol)
2018{
2019        if (!mpol_needs_cond_ref(frompol))
2020                return frompol;
2021
2022        *tompol = *frompol;
2023        tompol->flags &= ~MPOL_F_SHARED;        /* copy doesn't need unref */
2024        __mpol_put(frompol);
2025        return tompol;
2026}
2027
2028/* Slow path of a mempolicy comparison */
2029bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
2030{
2031        if (!a || !b)
2032                return false;
2033        if (a->mode != b->mode)
2034                return false;
2035        if (a->flags != b->flags)
2036                return false;
2037        if (mpol_store_user_nodemask(a))
2038                if (!nodes_equal(a->w.user_nodemask, b->w.user_nodemask))
2039                        return false;
2040
2041        switch (a->mode) {
2042        case MPOL_BIND:
2043                /* Fall through */
2044        case MPOL_INTERLEAVE:
2045                return !!nodes_equal(a->v.nodes, b->v.nodes);
2046        case MPOL_PREFERRED:
2047                return a->v.preferred_node == b->v.preferred_node;
2048        default:
2049                BUG();
2050                return false;
2051        }
2052}
2053
2054/*
2055 * Shared memory backing store policy support.
2056 *
2057 * Remember policies even when nobody has shared memory mapped.
2058 * The policies are kept in Red-Black tree linked from the inode.
2059 * They are protected by the sp->lock spinlock, which should be held
2060 * for any accesses to the tree.
2061 */
2062
2063/* lookup first element intersecting start-end */
2064/* Caller holds sp->lock */
2065static struct sp_node *
2066sp_lookup(struct shared_policy *sp, unsigned long start, unsigned long end)
2067{
2068        struct rb_node *n = sp->root.rb_node;
2069
2070        while (n) {
2071                struct sp_node *p = rb_entry(n, struct sp_node, nd);
2072
2073                if (start >= p->end)
2074                        n = n->rb_right;
2075                else if (end <= p->start)
2076                        n = n->rb_left;
2077                else
2078                        break;
2079        }
2080        if (!n)
2081                return NULL;
2082        for (;;) {
2083                struct sp_node *w = NULL;
2084                struct rb_node *prev = rb_prev(n);
2085                if (!prev)
2086                        break;
2087                w = rb_entry(prev, struct sp_node, nd);
2088                if (w->end <= start)
2089                        break;
2090                n = prev;
2091        }
2092        return rb_entry(n, struct sp_node, nd);
2093}
2094
2095/* Insert a new shared policy into the list. */
2096/* Caller holds sp->lock */
2097static void sp_insert(struct shared_policy *sp, struct sp_node *new)
2098{
2099        struct rb_node **p = &sp->root.rb_node;
2100        struct rb_node *parent = NULL;
2101        struct sp_node *nd;
2102
2103        while (*p) {
2104                parent = *p;
2105                nd = rb_entry(parent, struct sp_node, nd);
2106                if (new->start < nd->start)
2107                        p = &(*p)->rb_left;
2108                else if (new->end > nd->end)
2109                        p = &(*p)->rb_right;
2110                else
2111                        BUG();
2112        }
2113        rb_link_node(&new->nd, parent, p);
2114        rb_insert_color(&new->nd, &sp->root);
2115        pr_debug("inserting %lx-%lx: %d\n", new->start, new->end,
2116                 new->policy ? new->policy->mode : 0);
2117}
2118
2119/* Find shared policy intersecting idx */
2120struct mempolicy *
2121mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)
2122{
2123        struct mempolicy *pol = NULL;
2124        struct sp_node *sn;
2125
2126        if (!sp->root.rb_node)
2127                return NULL;
2128        spin_lock(&sp->lock);
2129        sn = sp_lookup(sp, idx, idx+1);
2130        if (sn) {
2131                mpol_get(sn->policy);
2132                pol = sn->policy;
2133        }
2134        spin_unlock(&sp->lock);
2135        return pol;
2136}
2137
2138static void sp_delete(struct shared_policy *sp, struct sp_node *n)
2139{
2140        pr_debug("deleting %lx-l%lx\n", n->start, n->end);
2141        rb_erase(&n->nd, &sp->root);
2142        mpol_put(n->policy);
2143        kmem_cache_free(sn_cache, n);
2144}
2145
2146static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
2147                                struct mempolicy *pol)
2148{
2149        struct sp_node *n = kmem_cache_alloc(sn_cache, GFP_KERNEL);
2150
2151        if (!n)
2152                return NULL;
2153        n->start = start;
2154        n->end = end;
2155        mpol_get(pol);
2156        pol->flags |= MPOL_F_SHARED;    /* for unref */
2157        n->policy = pol;
2158        return n;
2159}
2160
2161/* Replace a policy range. */
2162static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
2163                                 unsigned long end, struct sp_node *new)
2164{
2165        struct sp_node *n, *new2 = NULL;
2166
2167restart:
2168        spin_lock(&sp->lock);
2169        n = sp_lookup(sp, start, end);
2170        /* Take care of old policies in the same range. */
2171        while (n && n->start < end) {
2172                struct rb_node *next = rb_next(&n->nd);
2173                if (n->start >= start) {
2174                        if (n->end <= end)
2175                                sp_delete(sp, n);
2176                        else
2177                                n->start = end;
2178                } else {
2179                        /* Old policy spanning whole new range. */
2180                        if (n->end > end) {
2181                                if (!new2) {
2182                                        spin_unlock(&sp->lock);
2183                                        new2 = sp_alloc(end, n->end, n->policy);
2184                                        if (!new2)
2185                                                return -ENOMEM;
2186                                        goto restart;
2187                                }
2188                                n->end = start;
2189                                sp_insert(sp, new2);
2190                                new2 = NULL;
2191                                break;
2192                        } else
2193                                n->end = start;
2194                }
2195                if (!next)
2196                        break;
2197                n = rb_entry(next, struct sp_node, nd);
2198        }
2199        if (new)
2200                sp_insert(sp, new);
2201        spin_unlock(&sp->lock);
2202        if (new2) {
2203                mpol_put(new2->policy);
2204                kmem_cache_free(sn_cache, new2);
2205        }
2206        return 0;
2207}
2208
2209/**
2210 * mpol_shared_policy_init - initialize shared policy for inode
2211 * @sp: pointer to inode shared policy
2212 * @mpol:  struct mempolicy to install
2213 *
2214 * Install non-NULL @mpol in inode's shared policy rb-tree.
2215 * On entry, the current task has a reference on a non-NULL @mpol.
2216 * This must be released on exit.
2217 * This is called at get_inode() calls and we can use GFP_KERNEL.
2218 */
2219void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
2220{
2221        int ret;
2222
2223        sp->root = RB_ROOT;             /* empty tree == default mempolicy */
2224        spin_lock_init(&sp->lock);
2225
2226        if (mpol) {
2227                struct vm_area_struct pvma;
2228                struct mempolicy *new;
2229                NODEMASK_SCRATCH(scratch);
2230
2231                if (!scratch)
2232                        goto put_mpol;
2233                /* contextualize the tmpfs mount point mempolicy */
2234                new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
2235                if (IS_ERR(new))
2236                        goto free_scratch; /* no valid nodemask intersection */
2237
2238                task_lock(current);
2239                ret = mpol_set_nodemask(new, &mpol->w.user_nodemask, scratch);
2240                task_unlock(current);
2241                if (ret)
2242                        goto put_new;
2243
2244                /* Create pseudo-vma that contains just the policy */
2245                memset(&pvma, 0, sizeof(struct vm_area_struct));
2246                pvma.vm_end = TASK_SIZE;        /* policy covers entire file */
2247                mpol_set_shared_policy(sp, &pvma, new); /* adds ref */
2248
2249put_new:
2250                mpol_put(new);                  /* drop initial ref */
2251free_scratch:
2252                NODEMASK_SCRATCH_FREE(scratch);
2253put_mpol:
2254                mpol_put(mpol); /* drop our incoming ref on sb mpol */
2255        }
2256}
2257
2258int mpol_set_shared_policy(struct shared_policy *info,
2259                        struct vm_area_struct *vma, struct mempolicy *npol)
2260{
2261        int err;
2262        struct sp_node *new = NULL;
2263        unsigned long sz = vma_pages(vma);
2264
2265        pr_debug("set_shared_policy %lx sz %lu %d %d %lx\n",
2266                 vma->vm_pgoff,
2267                 sz, npol ? npol->mode : -1,
2268                 npol ? npol->flags : -1,
2269                 npol ? nodes_addr(npol->v.nodes)[0] : -1);
2270
2271        if (npol) {
2272                new = sp_alloc(vma->vm_pgoff, vma->vm_pgoff + sz, npol);
2273                if (!new)
2274                        return -ENOMEM;
2275        }
2276        err = shared_policy_replace(info, vma->vm_pgoff, vma->vm_pgoff+sz, new);
2277        if (err && new)
2278                kmem_cache_free(sn_cache, new);
2279        return err;
2280}
2281
2282/* Free a backing policy store on inode delete. */
2283void mpol_free_shared_policy(struct shared_policy *p)
2284{
2285        struct sp_node *n;
2286        struct rb_node *next;
2287
2288        if (!p->root.rb_node)
2289                return;
2290        spin_lock(&p->lock);
2291        next = rb_first(&p->root);
2292        while (next) {
2293                n = rb_entry(next, struct sp_node, nd);
2294                next = rb_next(&n->nd);
2295                rb_erase(&n->nd, &p->root);
2296                mpol_put(n->policy);
2297                kmem_cache_free(sn_cache, n);
2298        }
2299        spin_unlock(&p->lock);
2300}
2301
2302/* assumes fs == KERNEL_DS */
2303void __init numa_policy_init(void)
2304{
2305        nodemask_t interleave_nodes;
2306        unsigned long largest = 0;
2307        int nid, prefer = 0;
2308
2309        policy_cache = kmem_cache_create("numa_policy",
2310                                         sizeof(struct mempolicy),
2311                                         0, SLAB_PANIC, NULL);
2312
2313        sn_cache = kmem_cache_create("shared_policy_node",
2314                                     sizeof(struct sp_node),
2315                                     0, SLAB_PANIC, NULL);
2316
2317        /*
2318         * Set interleaving policy for system init. Interleaving is only
2319         * enabled across suitably sized nodes (default is >= 16MB), or
2320         * fall back to the largest node if they're all smaller.
2321         */
2322        nodes_clear(interleave_nodes);
2323        for_each_node_state(nid, N_HIGH_MEMORY) {
2324                unsigned long total_pages = node_present_pages(nid);
2325
2326                /* Preserve the largest node */
2327                if (largest < total_pages) {
2328                        largest = total_pages;
2329                        prefer = nid;
2330                }
2331
2332                /* Interleave this node? */
2333                if ((total_pages << PAGE_SHIFT) >= (16 << 20))
2334                        node_set(nid, interleave_nodes);
2335        }
2336
2337        /* All too small, use the largest */
2338        if (unlikely(nodes_empty(interleave_nodes)))
2339                node_set(prefer, interleave_nodes);
2340
2341        if (do_set_mempolicy(MPOL_INTERLEAVE, 0, &interleave_nodes))
2342                printk("numa_policy_init: interleaving failed\n");
2343}
2344
2345/* Reset policy of current process to default */
2346void numa_default_policy(void)
2347{
2348        do_set_mempolicy(MPOL_DEFAULT, 0, NULL);
2349}
2350
2351/*
2352 * Parse and format mempolicy from/to strings
2353 */
2354
2355/*
2356 * "local" is pseudo-policy:  MPOL_PREFERRED with MPOL_F_LOCAL flag
2357 * Used only for mpol_parse_str() and mpol_to_str()
2358 */
2359#define MPOL_LOCAL MPOL_MAX
2360static const char * const policy_modes[] =
2361{
2362        [MPOL_DEFAULT]    = "default",
2363        [MPOL_PREFERRED]  = "prefer",
2364        [MPOL_BIND]       = "bind",
2365        [MPOL_INTERLEAVE] = "interleave",
2366        [MPOL_LOCAL]      = "local"
2367};
2368
2369
2370#ifdef CONFIG_TMPFS
2371/**
2372 * mpol_parse_str - parse string to mempolicy
2373 * @str:  string containing mempolicy to parse
2374 * @mpol:  pointer to struct mempolicy pointer, returned on success.
2375 * @no_context:  flag whether to "contextualize" the mempolicy
2376 *
2377 * Format of input:
2378 *      <mode>[=<flags>][:<nodelist>]
2379 *
2380 * if @no_context is true, save the input nodemask in w.user_nodemask in
2381 * the returned mempolicy.  This will be used to "clone" the mempolicy in
2382 * a specific context [cpuset] at a later time.  Used to parse tmpfs mpol
2383 * mount option.  Note that if 'static' or 'relative' mode flags were
2384 * specified, the input nodemask will already have been saved.  Saving
2385 * it again is redundant, but safe.
2386 *
2387 * On success, returns 0, else 1
2388 */
2389int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
2390{
2391        struct mempolicy *new = NULL;
2392        unsigned short mode;
2393        unsigned short uninitialized_var(mode_flags);
2394        nodemask_t nodes;
2395        char *nodelist = strchr(str, ':');
2396        char *flags = strchr(str, '=');
2397        int err = 1;
2398
2399        if (nodelist) {
2400                /* NUL-terminate mode or flags string */
2401                *nodelist++ = '\0';
2402                if (nodelist_parse(nodelist, nodes))
2403                        goto out;
2404                if (!nodes_subset(nodes, node_states[N_HIGH_MEMORY]))
2405                        goto out;
2406        } else
2407                nodes_clear(nodes);
2408
2409        if (flags)
2410                *flags++ = '\0';        /* terminate mode string */
2411
2412        for (mode = 0; mode <= MPOL_LOCAL; mode++) {
2413                if (!strcmp(str, policy_modes[mode])) {
2414                        break;
2415                }
2416        }
2417        if (mode > MPOL_LOCAL)
2418                goto out;
2419
2420        switch (mode) {
2421        case MPOL_PREFERRED:
2422                /*
2423                 * Insist on a nodelist of one node only
2424                 */
2425                if (nodelist) {
2426                        char *rest = nodelist;
2427                        while (isdigit(*rest))
2428                                rest++;
2429                        if (*rest)
2430                                goto out;
2431                }
2432                break;
2433        case MPOL_INTERLEAVE:
2434                /*
2435                 * Default to online nodes with memory if no nodelist
2436                 */
2437                if (!nodelist)
2438                        nodes = node_states[N_HIGH_MEMORY];
2439                break;
2440        case MPOL_LOCAL:
2441                /*
2442                 * Don't allow a nodelist;  mpol_new() checks flags
2443                 */
2444                if (nodelist)
2445                        goto out;
2446                mode = MPOL_PREFERRED;
2447                break;
2448        case MPOL_DEFAULT:
2449                /*
2450                 * Insist on a empty nodelist
2451                 */
2452                if (!nodelist)
2453                        err = 0;
2454                goto out;
2455        case MPOL_BIND:
2456                /*
2457                 * Insist on a nodelist
2458                 */
2459                if (!nodelist)
2460                        goto out;
2461        }
2462
2463        mode_flags = 0;
2464        if (flags) {
2465                /*
2466                 * Currently, we only support two mutually exclusive
2467                 * mode flags.
2468                 */
2469                if (!strcmp(flags, "static"))
2470                        mode_flags |= MPOL_F_STATIC_NODES;
2471                else if (!strcmp(flags, "relative"))
2472                        mode_flags |= MPOL_F_RELATIVE_NODES;
2473                else
2474                        goto out;
2475        }
2476
2477        new = mpol_new(mode, mode_flags, &nodes);
2478        if (IS_ERR(new))
2479                goto out;
2480
2481        if (no_context) {
2482                /* save for contextualization */
2483                new->w.user_nodemask = nodes;
2484        } else {
2485                int ret;
2486                NODEMASK_SCRATCH(scratch);
2487                if (scratch) {
2488                        task_lock(current);
2489                        ret = mpol_set_nodemask(new, &nodes, scratch);
2490                        task_unlock(current);
2491                } else
2492                        ret = -ENOMEM;
2493                NODEMASK_SCRATCH_FREE(scratch);
2494                if (ret) {
2495                        mpol_put(new);
2496                        goto out;
2497                }
2498        }
2499        err = 0;
2500
2501out:
2502        /* Restore string for error message */
2503        if (nodelist)
2504                *--nodelist = ':';
2505        if (flags)
2506                *--flags = '=';
2507        if (!err)
2508                *mpol = new;
2509        return err;
2510}
2511#endif /* CONFIG_TMPFS */
2512
2513/**
2514 * mpol_to_str - format a mempolicy structure for printing
2515 * @buffer:  to contain formatted mempolicy string
2516 * @maxlen:  length of @buffer
2517 * @pol:  pointer to mempolicy to be formatted
2518 * @no_context:  "context free" mempolicy - use nodemask in w.user_nodemask
2519 *
2520 * Convert a mempolicy into a string.
2521 * Returns the number of characters in buffer (if positive)
2522 * or an error (negative)
2523 */
2524int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol, int no_context)
2525{
2526        char *p = buffer;
2527        int l;
2528        nodemask_t nodes;
2529        unsigned short mode;
2530        unsigned short flags = pol ? pol->flags : 0;
2531
2532        /*
2533         * Sanity check:  room for longest mode, flag and some nodes
2534         */
2535        VM_BUG_ON(maxlen < strlen("interleave") + strlen("relative") + 16);
2536
2537        if (!pol || pol == &default_policy)
2538                mode = MPOL_DEFAULT;
2539        else
2540                mode = pol->mode;
2541
2542        switch (mode) {
2543        case MPOL_DEFAULT:
2544                nodes_clear(nodes);
2545                break;
2546
2547        case MPOL_PREFERRED:
2548                nodes_clear(nodes);
2549                if (flags & MPOL_F_LOCAL)
2550                        mode = MPOL_LOCAL;      /* pseudo-policy */
2551                else
2552                        node_set(pol->v.preferred_node, nodes);
2553                break;
2554
2555        case MPOL_BIND:
2556                /* Fall through */
2557        case MPOL_INTERLEAVE:
2558                if (no_context)
2559                        nodes = pol->w.user_nodemask;
2560                else
2561                        nodes = pol->v.nodes;
2562                break;
2563
2564        default:
2565                return -EINVAL;
2566        }
2567
2568        l = strlen(policy_modes[mode]);
2569        if (buffer + maxlen < p + l + 1)
2570                return -ENOSPC;
2571
2572        strcpy(p, policy_modes[mode]);
2573        p += l;
2574
2575        if (flags & MPOL_MODE_FLAGS) {
2576                if (buffer + maxlen < p + 2)
2577                        return -ENOSPC;
2578                *p++ = '=';
2579
2580                /*
2581                 * Currently, the only defined flags are mutually exclusive
2582                 */
2583                if (flags & MPOL_F_STATIC_NODES)
2584                        p += snprintf(p, buffer + maxlen - p, "static");
2585                else if (flags & MPOL_F_RELATIVE_NODES)
2586                        p += snprintf(p, buffer + maxlen - p, "relative");
2587        }
2588
2589        if (!nodes_empty(nodes)) {
2590                if (buffer + maxlen < p + 2)
2591                        return -ENOSPC;
2592                *p++ = ':';
2593                p += nodelist_scnprintf(p, buffer + maxlen - p, nodes);
2594        }
2595        return p - buffer;
2596}
2597
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