linux/kernel/cpuset.c
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   1/*
   2 *  kernel/cpuset.c
   3 *
   4 *  Processor and Memory placement constraints for sets of tasks.
   5 *
   6 *  Copyright (C) 2003 BULL SA.
   7 *  Copyright (C) 2004-2007 Silicon Graphics, Inc.
   8 *  Copyright (C) 2006 Google, Inc
   9 *
  10 *  Portions derived from Patrick Mochel's sysfs code.
  11 *  sysfs is Copyright (c) 2001-3 Patrick Mochel
  12 *
  13 *  2003-10-10 Written by Simon Derr.
  14 *  2003-10-22 Updates by Stephen Hemminger.
  15 *  2004 May-July Rework by Paul Jackson.
  16 *  2006 Rework by Paul Menage to use generic cgroups
  17 *  2008 Rework of the scheduler domains and CPU hotplug handling
  18 *       by Max Krasnyansky
  19 *
  20 *  This file is subject to the terms and conditions of the GNU General Public
  21 *  License.  See the file COPYING in the main directory of the Linux
  22 *  distribution for more details.
  23 */
  24
  25#include <linux/cpu.h>
  26#include <linux/cpumask.h>
  27#include <linux/cpuset.h>
  28#include <linux/err.h>
  29#include <linux/errno.h>
  30#include <linux/file.h>
  31#include <linux/fs.h>
  32#include <linux/init.h>
  33#include <linux/interrupt.h>
  34#include <linux/kernel.h>
  35#include <linux/kmod.h>
  36#include <linux/list.h>
  37#include <linux/mempolicy.h>
  38#include <linux/mm.h>
  39#include <linux/memory.h>
  40#include <linux/module.h>
  41#include <linux/mount.h>
  42#include <linux/namei.h>
  43#include <linux/pagemap.h>
  44#include <linux/proc_fs.h>
  45#include <linux/rcupdate.h>
  46#include <linux/sched.h>
  47#include <linux/seq_file.h>
  48#include <linux/security.h>
  49#include <linux/slab.h>
  50#include <linux/spinlock.h>
  51#include <linux/stat.h>
  52#include <linux/string.h>
  53#include <linux/time.h>
  54#include <linux/backing-dev.h>
  55#include <linux/sort.h>
  56
  57#include <asm/uaccess.h>
  58#include <asm/atomic.h>
  59#include <linux/mutex.h>
  60#include <linux/workqueue.h>
  61#include <linux/cgroup.h>
  62
  63/*
  64 * Workqueue for cpuset related tasks.
  65 *
  66 * Using kevent workqueue may cause deadlock when memory_migrate
  67 * is set. So we create a separate workqueue thread for cpuset.
  68 */
  69static struct workqueue_struct *cpuset_wq;
  70
  71/*
  72 * Tracks how many cpusets are currently defined in system.
  73 * When there is only one cpuset (the root cpuset) we can
  74 * short circuit some hooks.
  75 */
  76int number_of_cpusets __read_mostly;
  77
  78/* Forward declare cgroup structures */
  79struct cgroup_subsys cpuset_subsys;
  80struct cpuset;
  81
  82/* See "Frequency meter" comments, below. */
  83
  84struct fmeter {
  85        int cnt;                /* unprocessed events count */
  86        int val;                /* most recent output value */
  87        time_t time;            /* clock (secs) when val computed */
  88        spinlock_t lock;        /* guards read or write of above */
  89};
  90
  91struct cpuset {
  92        struct cgroup_subsys_state css;
  93
  94        unsigned long flags;            /* "unsigned long" so bitops work */
  95        cpumask_var_t cpus_allowed;     /* CPUs allowed to tasks in cpuset */
  96        nodemask_t mems_allowed;        /* Memory Nodes allowed to tasks */
  97
  98        struct cpuset *parent;          /* my parent */
  99
 100        /*
 101         * Copy of global cpuset_mems_generation as of the most
 102         * recent time this cpuset changed its mems_allowed.
 103         */
 104        int mems_generation;
 105
 106        struct fmeter fmeter;           /* memory_pressure filter */
 107
 108        /* partition number for rebuild_sched_domains() */
 109        int pn;
 110
 111        /* for custom sched domain */
 112        int relax_domain_level;
 113
 114        /* used for walking a cpuset heirarchy */
 115        struct list_head stack_list;
 116};
 117
 118/* Retrieve the cpuset for a cgroup */
 119static inline struct cpuset *cgroup_cs(struct cgroup *cont)
 120{
 121        return container_of(cgroup_subsys_state(cont, cpuset_subsys_id),
 122                            struct cpuset, css);
 123}
 124
 125/* Retrieve the cpuset for a task */
 126static inline struct cpuset *task_cs(struct task_struct *task)
 127{
 128        return container_of(task_subsys_state(task, cpuset_subsys_id),
 129                            struct cpuset, css);
 130}
 131
 132/* bits in struct cpuset flags field */
 133typedef enum {
 134        CS_CPU_EXCLUSIVE,
 135        CS_MEM_EXCLUSIVE,
 136        CS_MEM_HARDWALL,
 137        CS_MEMORY_MIGRATE,
 138        CS_SCHED_LOAD_BALANCE,
 139        CS_SPREAD_PAGE,
 140        CS_SPREAD_SLAB,
 141} cpuset_flagbits_t;
 142
 143/* convenient tests for these bits */
 144static inline int is_cpu_exclusive(const struct cpuset *cs)
 145{
 146        return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
 147}
 148
 149static inline int is_mem_exclusive(const struct cpuset *cs)
 150{
 151        return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
 152}
 153
 154static inline int is_mem_hardwall(const struct cpuset *cs)
 155{
 156        return test_bit(CS_MEM_HARDWALL, &cs->flags);
 157}
 158
 159static inline int is_sched_load_balance(const struct cpuset *cs)
 160{
 161        return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
 162}
 163
 164static inline int is_memory_migrate(const struct cpuset *cs)
 165{
 166        return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
 167}
 168
 169static inline int is_spread_page(const struct cpuset *cs)
 170{
 171        return test_bit(CS_SPREAD_PAGE, &cs->flags);
 172}
 173
 174static inline int is_spread_slab(const struct cpuset *cs)
 175{
 176        return test_bit(CS_SPREAD_SLAB, &cs->flags);
 177}
 178
 179/*
 180 * Increment this integer everytime any cpuset changes its
 181 * mems_allowed value.  Users of cpusets can track this generation
 182 * number, and avoid having to lock and reload mems_allowed unless
 183 * the cpuset they're using changes generation.
 184 *
 185 * A single, global generation is needed because cpuset_attach_task() could
 186 * reattach a task to a different cpuset, which must not have its
 187 * generation numbers aliased with those of that tasks previous cpuset.
 188 *
 189 * Generations are needed for mems_allowed because one task cannot
 190 * modify another's memory placement.  So we must enable every task,
 191 * on every visit to __alloc_pages(), to efficiently check whether
 192 * its current->cpuset->mems_allowed has changed, requiring an update
 193 * of its current->mems_allowed.
 194 *
 195 * Since writes to cpuset_mems_generation are guarded by the cgroup lock
 196 * there is no need to mark it atomic.
 197 */
 198static int cpuset_mems_generation;
 199
 200static struct cpuset top_cpuset = {
 201        .flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
 202};
 203
 204/*
 205 * There are two global mutexes guarding cpuset structures.  The first
 206 * is the main control groups cgroup_mutex, accessed via
 207 * cgroup_lock()/cgroup_unlock().  The second is the cpuset-specific
 208 * callback_mutex, below. They can nest.  It is ok to first take
 209 * cgroup_mutex, then nest callback_mutex.  We also require taking
 210 * task_lock() when dereferencing a task's cpuset pointer.  See "The
 211 * task_lock() exception", at the end of this comment.
 212 *
 213 * A task must hold both mutexes to modify cpusets.  If a task
 214 * holds cgroup_mutex, then it blocks others wanting that mutex,
 215 * ensuring that it is the only task able to also acquire callback_mutex
 216 * and be able to modify cpusets.  It can perform various checks on
 217 * the cpuset structure first, knowing nothing will change.  It can
 218 * also allocate memory while just holding cgroup_mutex.  While it is
 219 * performing these checks, various callback routines can briefly
 220 * acquire callback_mutex to query cpusets.  Once it is ready to make
 221 * the changes, it takes callback_mutex, blocking everyone else.
 222 *
 223 * Calls to the kernel memory allocator can not be made while holding
 224 * callback_mutex, as that would risk double tripping on callback_mutex
 225 * from one of the callbacks into the cpuset code from within
 226 * __alloc_pages().
 227 *
 228 * If a task is only holding callback_mutex, then it has read-only
 229 * access to cpusets.
 230 *
 231 * The task_struct fields mems_allowed and mems_generation may only
 232 * be accessed in the context of that task, so require no locks.
 233 *
 234 * The cpuset_common_file_read() handlers only hold callback_mutex across
 235 * small pieces of code, such as when reading out possibly multi-word
 236 * cpumasks and nodemasks.
 237 *
 238 * Accessing a task's cpuset should be done in accordance with the
 239 * guidelines for accessing subsystem state in kernel/cgroup.c
 240 */
 241
 242static DEFINE_MUTEX(callback_mutex);
 243
 244/*
 245 * cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist
 246 * buffers.  They are statically allocated to prevent using excess stack
 247 * when calling cpuset_print_task_mems_allowed().
 248 */
 249#define CPUSET_NAME_LEN         (128)
 250#define CPUSET_NODELIST_LEN     (256)
 251static char cpuset_name[CPUSET_NAME_LEN];
 252static char cpuset_nodelist[CPUSET_NODELIST_LEN];
 253static DEFINE_SPINLOCK(cpuset_buffer_lock);
 254
 255/*
 256 * This is ugly, but preserves the userspace API for existing cpuset
 257 * users. If someone tries to mount the "cpuset" filesystem, we
 258 * silently switch it to mount "cgroup" instead
 259 */
 260static int cpuset_get_sb(struct file_system_type *fs_type,
 261                         int flags, const char *unused_dev_name,
 262                         void *data, struct vfsmount *mnt)
 263{
 264        struct file_system_type *cgroup_fs = get_fs_type("cgroup");
 265        int ret = -ENODEV;
 266        if (cgroup_fs) {
 267                char mountopts[] =
 268                        "cpuset,noprefix,"
 269                        "release_agent=/sbin/cpuset_release_agent";
 270                ret = cgroup_fs->get_sb(cgroup_fs, flags,
 271                                           unused_dev_name, mountopts, mnt);
 272                put_filesystem(cgroup_fs);
 273        }
 274        return ret;
 275}
 276
 277static struct file_system_type cpuset_fs_type = {
 278        .name = "cpuset",
 279        .get_sb = cpuset_get_sb,
 280};
 281
 282/*
 283 * Return in pmask the portion of a cpusets's cpus_allowed that
 284 * are online.  If none are online, walk up the cpuset hierarchy
 285 * until we find one that does have some online cpus.  If we get
 286 * all the way to the top and still haven't found any online cpus,
 287 * return cpu_online_map.  Or if passed a NULL cs from an exit'ing
 288 * task, return cpu_online_map.
 289 *
 290 * One way or another, we guarantee to return some non-empty subset
 291 * of cpu_online_map.
 292 *
 293 * Call with callback_mutex held.
 294 */
 295
 296static void guarantee_online_cpus(const struct cpuset *cs,
 297                                  struct cpumask *pmask)
 298{
 299        while (cs && !cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
 300                cs = cs->parent;
 301        if (cs)
 302                cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
 303        else
 304                cpumask_copy(pmask, cpu_online_mask);
 305        BUG_ON(!cpumask_intersects(pmask, cpu_online_mask));
 306}
 307
 308/*
 309 * Return in *pmask the portion of a cpusets's mems_allowed that
 310 * are online, with memory.  If none are online with memory, walk
 311 * up the cpuset hierarchy until we find one that does have some
 312 * online mems.  If we get all the way to the top and still haven't
 313 * found any online mems, return node_states[N_HIGH_MEMORY].
 314 *
 315 * One way or another, we guarantee to return some non-empty subset
 316 * of node_states[N_HIGH_MEMORY].
 317 *
 318 * Call with callback_mutex held.
 319 */
 320
 321static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
 322{
 323        while (cs && !nodes_intersects(cs->mems_allowed,
 324                                        node_states[N_HIGH_MEMORY]))
 325                cs = cs->parent;
 326        if (cs)
 327                nodes_and(*pmask, cs->mems_allowed,
 328                                        node_states[N_HIGH_MEMORY]);
 329        else
 330                *pmask = node_states[N_HIGH_MEMORY];
 331        BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY]));
 332}
 333
 334/**
 335 * cpuset_update_task_memory_state - update task memory placement
 336 *
 337 * If the current tasks cpusets mems_allowed changed behind our
 338 * backs, update current->mems_allowed, mems_generation and task NUMA
 339 * mempolicy to the new value.
 340 *
 341 * Task mempolicy is updated by rebinding it relative to the
 342 * current->cpuset if a task has its memory placement changed.
 343 * Do not call this routine if in_interrupt().
 344 *
 345 * Call without callback_mutex or task_lock() held.  May be
 346 * called with or without cgroup_mutex held.  Thanks in part to
 347 * 'the_top_cpuset_hack', the task's cpuset pointer will never
 348 * be NULL.  This routine also might acquire callback_mutex during
 349 * call.
 350 *
 351 * Reading current->cpuset->mems_generation doesn't need task_lock
 352 * to guard the current->cpuset derefence, because it is guarded
 353 * from concurrent freeing of current->cpuset using RCU.
 354 *
 355 * The rcu_dereference() is technically probably not needed,
 356 * as I don't actually mind if I see a new cpuset pointer but
 357 * an old value of mems_generation.  However this really only
 358 * matters on alpha systems using cpusets heavily.  If I dropped
 359 * that rcu_dereference(), it would save them a memory barrier.
 360 * For all other arch's, rcu_dereference is a no-op anyway, and for
 361 * alpha systems not using cpusets, another planned optimization,
 362 * avoiding the rcu critical section for tasks in the root cpuset
 363 * which is statically allocated, so can't vanish, will make this
 364 * irrelevant.  Better to use RCU as intended, than to engage in
 365 * some cute trick to save a memory barrier that is impossible to
 366 * test, for alpha systems using cpusets heavily, which might not
 367 * even exist.
 368 *
 369 * This routine is needed to update the per-task mems_allowed data,
 370 * within the tasks context, when it is trying to allocate memory
 371 * (in various mm/mempolicy.c routines) and notices that some other
 372 * task has been modifying its cpuset.
 373 */
 374
 375void cpuset_update_task_memory_state(void)
 376{
 377        int my_cpusets_mem_gen;
 378        struct task_struct *tsk = current;
 379        struct cpuset *cs;
 380
 381        rcu_read_lock();
 382        my_cpusets_mem_gen = task_cs(tsk)->mems_generation;
 383        rcu_read_unlock();
 384
 385        if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
 386                mutex_lock(&callback_mutex);
 387                task_lock(tsk);
 388                cs = task_cs(tsk); /* Maybe changed when task not locked */
 389                guarantee_online_mems(cs, &tsk->mems_allowed);
 390                tsk->cpuset_mems_generation = cs->mems_generation;
 391                if (is_spread_page(cs))
 392                        tsk->flags |= PF_SPREAD_PAGE;
 393                else
 394                        tsk->flags &= ~PF_SPREAD_PAGE;
 395                if (is_spread_slab(cs))
 396                        tsk->flags |= PF_SPREAD_SLAB;
 397                else
 398                        tsk->flags &= ~PF_SPREAD_SLAB;
 399                task_unlock(tsk);
 400                mutex_unlock(&callback_mutex);
 401                mpol_rebind_task(tsk, &tsk->mems_allowed);
 402        }
 403}
 404
 405/*
 406 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
 407 *
 408 * One cpuset is a subset of another if all its allowed CPUs and
 409 * Memory Nodes are a subset of the other, and its exclusive flags
 410 * are only set if the other's are set.  Call holding cgroup_mutex.
 411 */
 412
 413static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
 414{
 415        return  cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
 416                nodes_subset(p->mems_allowed, q->mems_allowed) &&
 417                is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
 418                is_mem_exclusive(p) <= is_mem_exclusive(q);
 419}
 420
 421/**
 422 * alloc_trial_cpuset - allocate a trial cpuset
 423 * @cs: the cpuset that the trial cpuset duplicates
 424 */
 425static struct cpuset *alloc_trial_cpuset(const struct cpuset *cs)
 426{
 427        struct cpuset *trial;
 428
 429        trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
 430        if (!trial)
 431                return NULL;
 432
 433        if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL)) {
 434                kfree(trial);
 435                return NULL;
 436        }
 437        cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
 438
 439        return trial;
 440}
 441
 442/**
 443 * free_trial_cpuset - free the trial cpuset
 444 * @trial: the trial cpuset to be freed
 445 */
 446static void free_trial_cpuset(struct cpuset *trial)
 447{
 448        free_cpumask_var(trial->cpus_allowed);
 449        kfree(trial);
 450}
 451
 452/*
 453 * validate_change() - Used to validate that any proposed cpuset change
 454 *                     follows the structural rules for cpusets.
 455 *
 456 * If we replaced the flag and mask values of the current cpuset
 457 * (cur) with those values in the trial cpuset (trial), would
 458 * our various subset and exclusive rules still be valid?  Presumes
 459 * cgroup_mutex held.
 460 *
 461 * 'cur' is the address of an actual, in-use cpuset.  Operations
 462 * such as list traversal that depend on the actual address of the
 463 * cpuset in the list must use cur below, not trial.
 464 *
 465 * 'trial' is the address of bulk structure copy of cur, with
 466 * perhaps one or more of the fields cpus_allowed, mems_allowed,
 467 * or flags changed to new, trial values.
 468 *
 469 * Return 0 if valid, -errno if not.
 470 */
 471
 472static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
 473{
 474        struct cgroup *cont;
 475        struct cpuset *c, *par;
 476
 477        /* Each of our child cpusets must be a subset of us */
 478        list_for_each_entry(cont, &cur->css.cgroup->children, sibling) {
 479                if (!is_cpuset_subset(cgroup_cs(cont), trial))
 480                        return -EBUSY;
 481        }
 482
 483        /* Remaining checks don't apply to root cpuset */
 484        if (cur == &top_cpuset)
 485                return 0;
 486
 487        par = cur->parent;
 488
 489        /* We must be a subset of our parent cpuset */
 490        if (!is_cpuset_subset(trial, par))
 491                return -EACCES;
 492
 493        /*
 494         * If either I or some sibling (!= me) is exclusive, we can't
 495         * overlap
 496         */
 497        list_for_each_entry(cont, &par->css.cgroup->children, sibling) {
 498                c = cgroup_cs(cont);
 499                if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
 500                    c != cur &&
 501                    cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
 502                        return -EINVAL;
 503                if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
 504                    c != cur &&
 505                    nodes_intersects(trial->mems_allowed, c->mems_allowed))
 506                        return -EINVAL;
 507        }
 508
 509        /* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
 510        if (cgroup_task_count(cur->css.cgroup)) {
 511                if (cpumask_empty(trial->cpus_allowed) ||
 512                    nodes_empty(trial->mems_allowed)) {
 513                        return -ENOSPC;
 514                }
 515        }
 516
 517        return 0;
 518}
 519
 520#ifdef CONFIG_SMP
 521/*
 522 * Helper routine for generate_sched_domains().
 523 * Do cpusets a, b have overlapping cpus_allowed masks?
 524 */
 525static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
 526{
 527        return cpumask_intersects(a->cpus_allowed, b->cpus_allowed);
 528}
 529
 530static void
 531update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
 532{
 533        if (dattr->relax_domain_level < c->relax_domain_level)
 534                dattr->relax_domain_level = c->relax_domain_level;
 535        return;
 536}
 537
 538static void
 539update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c)
 540{
 541        LIST_HEAD(q);
 542
 543        list_add(&c->stack_list, &q);
 544        while (!list_empty(&q)) {
 545                struct cpuset *cp;
 546                struct cgroup *cont;
 547                struct cpuset *child;
 548
 549                cp = list_first_entry(&q, struct cpuset, stack_list);
 550                list_del(q.next);
 551
 552                if (cpumask_empty(cp->cpus_allowed))
 553                        continue;
 554
 555                if (is_sched_load_balance(cp))
 556                        update_domain_attr(dattr, cp);
 557
 558                list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
 559                        child = cgroup_cs(cont);
 560                        list_add_tail(&child->stack_list, &q);
 561                }
 562        }
 563}
 564
 565/*
 566 * generate_sched_domains()
 567 *
 568 * This function builds a partial partition of the systems CPUs
 569 * A 'partial partition' is a set of non-overlapping subsets whose
 570 * union is a subset of that set.
 571 * The output of this function needs to be passed to kernel/sched.c
 572 * partition_sched_domains() routine, which will rebuild the scheduler's
 573 * load balancing domains (sched domains) as specified by that partial
 574 * partition.
 575 *
 576 * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
 577 * for a background explanation of this.
 578 *
 579 * Does not return errors, on the theory that the callers of this
 580 * routine would rather not worry about failures to rebuild sched
 581 * domains when operating in the severe memory shortage situations
 582 * that could cause allocation failures below.
 583 *
 584 * Must be called with cgroup_lock held.
 585 *
 586 * The three key local variables below are:
 587 *    q  - a linked-list queue of cpuset pointers, used to implement a
 588 *         top-down scan of all cpusets.  This scan loads a pointer
 589 *         to each cpuset marked is_sched_load_balance into the
 590 *         array 'csa'.  For our purposes, rebuilding the schedulers
 591 *         sched domains, we can ignore !is_sched_load_balance cpusets.
 592 *  csa  - (for CpuSet Array) Array of pointers to all the cpusets
 593 *         that need to be load balanced, for convenient iterative
 594 *         access by the subsequent code that finds the best partition,
 595 *         i.e the set of domains (subsets) of CPUs such that the
 596 *         cpus_allowed of every cpuset marked is_sched_load_balance
 597 *         is a subset of one of these domains, while there are as
 598 *         many such domains as possible, each as small as possible.
 599 * doms  - Conversion of 'csa' to an array of cpumasks, for passing to
 600 *         the kernel/sched.c routine partition_sched_domains() in a
 601 *         convenient format, that can be easily compared to the prior
 602 *         value to determine what partition elements (sched domains)
 603 *         were changed (added or removed.)
 604 *
 605 * Finding the best partition (set of domains):
 606 *      The triple nested loops below over i, j, k scan over the
 607 *      load balanced cpusets (using the array of cpuset pointers in
 608 *      csa[]) looking for pairs of cpusets that have overlapping
 609 *      cpus_allowed, but which don't have the same 'pn' partition
 610 *      number and gives them in the same partition number.  It keeps
 611 *      looping on the 'restart' label until it can no longer find
 612 *      any such pairs.
 613 *
 614 *      The union of the cpus_allowed masks from the set of
 615 *      all cpusets having the same 'pn' value then form the one
 616 *      element of the partition (one sched domain) to be passed to
 617 *      partition_sched_domains().
 618 */
 619/* FIXME: see the FIXME in partition_sched_domains() */
 620static int generate_sched_domains(struct cpumask **domains,
 621                        struct sched_domain_attr **attributes)
 622{
 623        LIST_HEAD(q);           /* queue of cpusets to be scanned */
 624        struct cpuset *cp;      /* scans q */
 625        struct cpuset **csa;    /* array of all cpuset ptrs */
 626        int csn;                /* how many cpuset ptrs in csa so far */
 627        int i, j, k;            /* indices for partition finding loops */
 628        struct cpumask *doms;   /* resulting partition; i.e. sched domains */
 629        struct sched_domain_attr *dattr;  /* attributes for custom domains */
 630        int ndoms = 0;          /* number of sched domains in result */
 631        int nslot;              /* next empty doms[] struct cpumask slot */
 632
 633        doms = NULL;
 634        dattr = NULL;
 635        csa = NULL;
 636
 637        /* Special case for the 99% of systems with one, full, sched domain */
 638        if (is_sched_load_balance(&top_cpuset)) {
 639                doms = kmalloc(cpumask_size(), GFP_KERNEL);
 640                if (!doms)
 641                        goto done;
 642
 643                dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
 644                if (dattr) {
 645                        *dattr = SD_ATTR_INIT;
 646                        update_domain_attr_tree(dattr, &top_cpuset);
 647                }
 648                cpumask_copy(doms, top_cpuset.cpus_allowed);
 649
 650                ndoms = 1;
 651                goto done;
 652        }
 653
 654        csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
 655        if (!csa)
 656                goto done;
 657        csn = 0;
 658
 659        list_add(&top_cpuset.stack_list, &q);
 660        while (!list_empty(&q)) {
 661                struct cgroup *cont;
 662                struct cpuset *child;   /* scans child cpusets of cp */
 663
 664                cp = list_first_entry(&q, struct cpuset, stack_list);
 665                list_del(q.next);
 666
 667                if (cpumask_empty(cp->cpus_allowed))
 668                        continue;
 669
 670                /*
 671                 * All child cpusets contain a subset of the parent's cpus, so
 672                 * just skip them, and then we call update_domain_attr_tree()
 673                 * to calc relax_domain_level of the corresponding sched
 674                 * domain.
 675                 */
 676                if (is_sched_load_balance(cp)) {
 677                        csa[csn++] = cp;
 678                        continue;
 679                }
 680
 681                list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
 682                        child = cgroup_cs(cont);
 683                        list_add_tail(&child->stack_list, &q);
 684                }
 685        }
 686
 687        for (i = 0; i < csn; i++)
 688                csa[i]->pn = i;
 689        ndoms = csn;
 690
 691restart:
 692        /* Find the best partition (set of sched domains) */
 693        for (i = 0; i < csn; i++) {
 694                struct cpuset *a = csa[i];
 695                int apn = a->pn;
 696
 697                for (j = 0; j < csn; j++) {
 698                        struct cpuset *b = csa[j];
 699                        int bpn = b->pn;
 700
 701                        if (apn != bpn && cpusets_overlap(a, b)) {
 702                                for (k = 0; k < csn; k++) {
 703                                        struct cpuset *c = csa[k];
 704
 705                                        if (c->pn == bpn)
 706                                                c->pn = apn;
 707                                }
 708                                ndoms--;        /* one less element */
 709                                goto restart;
 710                        }
 711                }
 712        }
 713
 714        /*
 715         * Now we know how many domains to create.
 716         * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
 717         */
 718        doms = kmalloc(ndoms * cpumask_size(), GFP_KERNEL);
 719        if (!doms)
 720                goto done;
 721
 722        /*
 723         * The rest of the code, including the scheduler, can deal with
 724         * dattr==NULL case. No need to abort if alloc fails.
 725         */
 726        dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
 727
 728        for (nslot = 0, i = 0; i < csn; i++) {
 729                struct cpuset *a = csa[i];
 730                struct cpumask *dp;
 731                int apn = a->pn;
 732
 733                if (apn < 0) {
 734                        /* Skip completed partitions */
 735                        continue;
 736                }
 737
 738                dp = doms + nslot;
 739
 740                if (nslot == ndoms) {
 741                        static int warnings = 10;
 742                        if (warnings) {
 743                                printk(KERN_WARNING
 744                                 "rebuild_sched_domains confused:"
 745                                  " nslot %d, ndoms %d, csn %d, i %d,"
 746                                  " apn %d\n",
 747                                  nslot, ndoms, csn, i, apn);
 748                                warnings--;
 749                        }
 750                        continue;
 751                }
 752
 753                cpumask_clear(dp);
 754                if (dattr)
 755                        *(dattr + nslot) = SD_ATTR_INIT;
 756                for (j = i; j < csn; j++) {
 757                        struct cpuset *b = csa[j];
 758
 759                        if (apn == b->pn) {
 760                                cpumask_or(dp, dp, b->cpus_allowed);
 761                                if (dattr)
 762                                        update_domain_attr_tree(dattr + nslot, b);
 763
 764                                /* Done with this partition */
 765                                b->pn = -1;
 766                        }
 767                }
 768                nslot++;
 769        }
 770        BUG_ON(nslot != ndoms);
 771
 772done:
 773        kfree(csa);
 774
 775        /*
 776         * Fallback to the default domain if kmalloc() failed.
 777         * See comments in partition_sched_domains().
 778         */
 779        if (doms == NULL)
 780                ndoms = 1;
 781
 782        *domains    = doms;
 783        *attributes = dattr;
 784        return ndoms;
 785}
 786
 787/*
 788 * Rebuild scheduler domains.
 789 *
 790 * Call with neither cgroup_mutex held nor within get_online_cpus().
 791 * Takes both cgroup_mutex and get_online_cpus().
 792 *
 793 * Cannot be directly called from cpuset code handling changes
 794 * to the cpuset pseudo-filesystem, because it cannot be called
 795 * from code that already holds cgroup_mutex.
 796 */
 797static void do_rebuild_sched_domains(struct work_struct *unused)
 798{
 799        struct sched_domain_attr *attr;
 800        struct cpumask *doms;
 801        int ndoms;
 802
 803        get_online_cpus();
 804
 805        /* Generate domain masks and attrs */
 806        cgroup_lock();
 807        ndoms = generate_sched_domains(&doms, &attr);
 808        cgroup_unlock();
 809
 810        /* Have scheduler rebuild the domains */
 811        partition_sched_domains(ndoms, doms, attr);
 812
 813        put_online_cpus();
 814}
 815#else /* !CONFIG_SMP */
 816static void do_rebuild_sched_domains(struct work_struct *unused)
 817{
 818}
 819
 820static int generate_sched_domains(struct cpumask **domains,
 821                        struct sched_domain_attr **attributes)
 822{
 823        *domains = NULL;
 824        return 1;
 825}
 826#endif /* CONFIG_SMP */
 827
 828static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);
 829
 830/*
 831 * Rebuild scheduler domains, asynchronously via workqueue.
 832 *
 833 * If the flag 'sched_load_balance' of any cpuset with non-empty
 834 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
 835 * which has that flag enabled, or if any cpuset with a non-empty
 836 * 'cpus' is removed, then call this routine to rebuild the
 837 * scheduler's dynamic sched domains.
 838 *
 839 * The rebuild_sched_domains() and partition_sched_domains()
 840 * routines must nest cgroup_lock() inside get_online_cpus(),
 841 * but such cpuset changes as these must nest that locking the
 842 * other way, holding cgroup_lock() for much of the code.
 843 *
 844 * So in order to avoid an ABBA deadlock, the cpuset code handling
 845 * these user changes delegates the actual sched domain rebuilding
 846 * to a separate workqueue thread, which ends up processing the
 847 * above do_rebuild_sched_domains() function.
 848 */
 849static void async_rebuild_sched_domains(void)
 850{
 851        queue_work(cpuset_wq, &rebuild_sched_domains_work);
 852}
 853
 854/*
 855 * Accomplishes the same scheduler domain rebuild as the above
 856 * async_rebuild_sched_domains(), however it directly calls the
 857 * rebuild routine synchronously rather than calling it via an
 858 * asynchronous work thread.
 859 *
 860 * This can only be called from code that is not holding
 861 * cgroup_mutex (not nested in a cgroup_lock() call.)
 862 */
 863void rebuild_sched_domains(void)
 864{
 865        do_rebuild_sched_domains(NULL);
 866}
 867
 868/**
 869 * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's
 870 * @tsk: task to test
 871 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
 872 *
 873 * Call with cgroup_mutex held.  May take callback_mutex during call.
 874 * Called for each task in a cgroup by cgroup_scan_tasks().
 875 * Return nonzero if this tasks's cpus_allowed mask should be changed (in other
 876 * words, if its mask is not equal to its cpuset's mask).
 877 */
 878static int cpuset_test_cpumask(struct task_struct *tsk,
 879                               struct cgroup_scanner *scan)
 880{
 881        return !cpumask_equal(&tsk->cpus_allowed,
 882                        (cgroup_cs(scan->cg))->cpus_allowed);
 883}
 884
 885/**
 886 * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
 887 * @tsk: task to test
 888 * @scan: struct cgroup_scanner containing the cgroup of the task
 889 *
 890 * Called by cgroup_scan_tasks() for each task in a cgroup whose
 891 * cpus_allowed mask needs to be changed.
 892 *
 893 * We don't need to re-check for the cgroup/cpuset membership, since we're
 894 * holding cgroup_lock() at this point.
 895 */
 896static void cpuset_change_cpumask(struct task_struct *tsk,
 897                                  struct cgroup_scanner *scan)
 898{
 899        set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed));
 900}
 901
 902/**
 903 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
 904 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
 905 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
 906 *
 907 * Called with cgroup_mutex held
 908 *
 909 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
 910 * calling callback functions for each.
 911 *
 912 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
 913 * if @heap != NULL.
 914 */
 915static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
 916{
 917        struct cgroup_scanner scan;
 918
 919        scan.cg = cs->css.cgroup;
 920        scan.test_task = cpuset_test_cpumask;
 921        scan.process_task = cpuset_change_cpumask;
 922        scan.heap = heap;
 923        cgroup_scan_tasks(&scan);
 924}
 925
 926/**
 927 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
 928 * @cs: the cpuset to consider
 929 * @buf: buffer of cpu numbers written to this cpuset
 930 */
 931static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
 932                          const char *buf)
 933{
 934        struct ptr_heap heap;
 935        int retval;
 936        int is_load_balanced;
 937
 938        /* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */
 939        if (cs == &top_cpuset)
 940                return -EACCES;
 941
 942        /*
 943         * An empty cpus_allowed is ok only if the cpuset has no tasks.
 944         * Since cpulist_parse() fails on an empty mask, we special case
 945         * that parsing.  The validate_change() call ensures that cpusets
 946         * with tasks have cpus.
 947         */
 948        if (!*buf) {
 949                cpumask_clear(trialcs->cpus_allowed);
 950        } else {
 951                retval = cpulist_parse(buf, trialcs->cpus_allowed);
 952                if (retval < 0)
 953                        return retval;
 954
 955                if (!cpumask_subset(trialcs->cpus_allowed, cpu_online_mask))
 956                        return -EINVAL;
 957        }
 958        retval = validate_change(cs, trialcs);
 959        if (retval < 0)
 960                return retval;
 961
 962        /* Nothing to do if the cpus didn't change */
 963        if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
 964                return 0;
 965
 966        retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
 967        if (retval)
 968                return retval;
 969
 970        is_load_balanced = is_sched_load_balance(trialcs);
 971
 972        mutex_lock(&callback_mutex);
 973        cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
 974        mutex_unlock(&callback_mutex);
 975
 976        /*
 977         * Scan tasks in the cpuset, and update the cpumasks of any
 978         * that need an update.
 979         */
 980        update_tasks_cpumask(cs, &heap);
 981
 982        heap_free(&heap);
 983
 984        if (is_load_balanced)
 985                async_rebuild_sched_domains();
 986        return 0;
 987}
 988
 989/*
 990 * cpuset_migrate_mm
 991 *
 992 *    Migrate memory region from one set of nodes to another.
 993 *
 994 *    Temporarilly set tasks mems_allowed to target nodes of migration,
 995 *    so that the migration code can allocate pages on these nodes.
 996 *
 997 *    Call holding cgroup_mutex, so current's cpuset won't change
 998 *    during this call, as manage_mutex holds off any cpuset_attach()
 999 *    calls.  Therefore we don't need to take task_lock around the
1000 *    call to guarantee_online_mems(), as we know no one is changing
1001 *    our task's cpuset.
1002 *
1003 *    Hold callback_mutex around the two modifications of our tasks
1004 *    mems_allowed to synchronize with cpuset_mems_allowed().
1005 *
1006 *    While the mm_struct we are migrating is typically from some
1007 *    other task, the task_struct mems_allowed that we are hacking
1008 *    is for our current task, which must allocate new pages for that
1009 *    migrating memory region.
1010 *
1011 *    We call cpuset_update_task_memory_state() before hacking
1012 *    our tasks mems_allowed, so that we are assured of being in
1013 *    sync with our tasks cpuset, and in particular, callbacks to
1014 *    cpuset_update_task_memory_state() from nested page allocations
1015 *    won't see any mismatch of our cpuset and task mems_generation
1016 *    values, so won't overwrite our hacked tasks mems_allowed
1017 *    nodemask.
1018 */
1019
1020static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
1021                                                        const nodemask_t *to)
1022{
1023        struct task_struct *tsk = current;
1024
1025        cpuset_update_task_memory_state();
1026
1027        mutex_lock(&callback_mutex);
1028        tsk->mems_allowed = *to;
1029        mutex_unlock(&callback_mutex);
1030
1031        do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
1032
1033        mutex_lock(&callback_mutex);
1034        guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
1035        mutex_unlock(&callback_mutex);
1036}
1037
1038/*
1039 * Rebind task's vmas to cpuset's new mems_allowed, and migrate pages to new
1040 * nodes if memory_migrate flag is set. Called with cgroup_mutex held.
1041 */
1042static void cpuset_change_nodemask(struct task_struct *p,
1043                                   struct cgroup_scanner *scan)
1044{
1045        struct mm_struct *mm;
1046        struct cpuset *cs;
1047        int migrate;
1048        const nodemask_t *oldmem = scan->data;
1049
1050        mm = get_task_mm(p);
1051        if (!mm)
1052                return;
1053
1054        cs = cgroup_cs(scan->cg);
1055        migrate = is_memory_migrate(cs);
1056
1057        mpol_rebind_mm(mm, &cs->mems_allowed);
1058        if (migrate)
1059                cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
1060        mmput(mm);
1061}
1062
1063static void *cpuset_being_rebound;
1064
1065/**
1066 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1067 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1068 * @oldmem: old mems_allowed of cpuset cs
1069 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1070 *
1071 * Called with cgroup_mutex held
1072 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
1073 * if @heap != NULL.
1074 */
1075static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
1076                                 struct ptr_heap *heap)
1077{
1078        struct cgroup_scanner scan;
1079
1080        cpuset_being_rebound = cs;              /* causes mpol_dup() rebind */
1081
1082        scan.cg = cs->css.cgroup;
1083        scan.test_task = NULL;
1084        scan.process_task = cpuset_change_nodemask;
1085        scan.heap = heap;
1086        scan.data = (nodemask_t *)oldmem;
1087
1088        /*
1089         * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
1090         * take while holding tasklist_lock.  Forks can happen - the
1091         * mpol_dup() cpuset_being_rebound check will catch such forks,
1092         * and rebind their vma mempolicies too.  Because we still hold
1093         * the global cgroup_mutex, we know that no other rebind effort
1094         * will be contending for the global variable cpuset_being_rebound.
1095         * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1096         * is idempotent.  Also migrate pages in each mm to new nodes.
1097         */
1098        cgroup_scan_tasks(&scan);
1099
1100        /* We're done rebinding vmas to this cpuset's new mems_allowed. */
1101        cpuset_being_rebound = NULL;
1102}
1103
1104/*
1105 * Handle user request to change the 'mems' memory placement
1106 * of a cpuset.  Needs to validate the request, update the
1107 * cpusets mems_allowed and mems_generation, and for each
1108 * task in the cpuset, rebind any vma mempolicies and if
1109 * the cpuset is marked 'memory_migrate', migrate the tasks
1110 * pages to the new memory.
1111 *
1112 * Call with cgroup_mutex held.  May take callback_mutex during call.
1113 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1114 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
1115 * their mempolicies to the cpusets new mems_allowed.
1116 */
1117static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
1118                           const char *buf)
1119{
1120        nodemask_t oldmem;
1121        int retval;
1122        struct ptr_heap heap;
1123
1124        /*
1125         * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
1126         * it's read-only
1127         */
1128        if (cs == &top_cpuset)
1129                return -EACCES;
1130
1131        /*
1132         * An empty mems_allowed is ok iff there are no tasks in the cpuset.
1133         * Since nodelist_parse() fails on an empty mask, we special case
1134         * that parsing.  The validate_change() call ensures that cpusets
1135         * with tasks have memory.
1136         */
1137        if (!*buf) {
1138                nodes_clear(trialcs->mems_allowed);
1139        } else {
1140                retval = nodelist_parse(buf, trialcs->mems_allowed);
1141                if (retval < 0)
1142                        goto done;
1143
1144                if (!nodes_subset(trialcs->mems_allowed,
1145                                node_states[N_HIGH_MEMORY]))
1146                        return -EINVAL;
1147        }
1148        oldmem = cs->mems_allowed;
1149        if (nodes_equal(oldmem, trialcs->mems_allowed)) {
1150                retval = 0;             /* Too easy - nothing to do */
1151                goto done;
1152        }
1153        retval = validate_change(cs, trialcs);
1154        if (retval < 0)
1155                goto done;
1156
1157        retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
1158        if (retval < 0)
1159                goto done;
1160
1161        mutex_lock(&callback_mutex);
1162        cs->mems_allowed = trialcs->mems_allowed;
1163        cs->mems_generation = cpuset_mems_generation++;
1164        mutex_unlock(&callback_mutex);
1165
1166        update_tasks_nodemask(cs, &oldmem, &heap);
1167
1168        heap_free(&heap);
1169done:
1170        return retval;
1171}
1172
1173int current_cpuset_is_being_rebound(void)
1174{
1175        return task_cs(current) == cpuset_being_rebound;
1176}
1177
1178static int update_relax_domain_level(struct cpuset *cs, s64 val)
1179{
1180#ifdef CONFIG_SMP
1181        if (val < -1 || val >= SD_LV_MAX)
1182                return -EINVAL;
1183#endif
1184
1185        if (val != cs->relax_domain_level) {
1186                cs->relax_domain_level = val;
1187                if (!cpumask_empty(cs->cpus_allowed) &&
1188                    is_sched_load_balance(cs))
1189                        async_rebuild_sched_domains();
1190        }
1191
1192        return 0;
1193}
1194
1195/*
1196 * update_flag - read a 0 or a 1 in a file and update associated flag
1197 * bit:         the bit to update (see cpuset_flagbits_t)
1198 * cs:          the cpuset to update
1199 * turning_on:  whether the flag is being set or cleared
1200 *
1201 * Call with cgroup_mutex held.
1202 */
1203
1204static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1205                       int turning_on)
1206{
1207        struct cpuset *trialcs;
1208        int err;
1209        int balance_flag_changed;
1210
1211        trialcs = alloc_trial_cpuset(cs);
1212        if (!trialcs)
1213                return -ENOMEM;
1214
1215        if (turning_on)
1216                set_bit(bit, &trialcs->flags);
1217        else
1218                clear_bit(bit, &trialcs->flags);
1219
1220        err = validate_change(cs, trialcs);
1221        if (err < 0)
1222                goto out;
1223
1224        balance_flag_changed = (is_sched_load_balance(cs) !=
1225                                is_sched_load_balance(trialcs));
1226
1227        mutex_lock(&callback_mutex);
1228        cs->flags = trialcs->flags;
1229        mutex_unlock(&callback_mutex);
1230
1231        if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1232                async_rebuild_sched_domains();
1233
1234out:
1235        free_trial_cpuset(trialcs);
1236        return err;
1237}
1238
1239/*
1240 * Frequency meter - How fast is some event occurring?
1241 *
1242 * These routines manage a digitally filtered, constant time based,
1243 * event frequency meter.  There are four routines:
1244 *   fmeter_init() - initialize a frequency meter.
1245 *   fmeter_markevent() - called each time the event happens.
1246 *   fmeter_getrate() - returns the recent rate of such events.
1247 *   fmeter_update() - internal routine used to update fmeter.
1248 *
1249 * A common data structure is passed to each of these routines,
1250 * which is used to keep track of the state required to manage the
1251 * frequency meter and its digital filter.
1252 *
1253 * The filter works on the number of events marked per unit time.
1254 * The filter is single-pole low-pass recursive (IIR).  The time unit
1255 * is 1 second.  Arithmetic is done using 32-bit integers scaled to
1256 * simulate 3 decimal digits of precision (multiplied by 1000).
1257 *
1258 * With an FM_COEF of 933, and a time base of 1 second, the filter
1259 * has a half-life of 10 seconds, meaning that if the events quit
1260 * happening, then the rate returned from the fmeter_getrate()
1261 * will be cut in half each 10 seconds, until it converges to zero.
1262 *
1263 * It is not worth doing a real infinitely recursive filter.  If more
1264 * than FM_MAXTICKS ticks have elapsed since the last filter event,
1265 * just compute FM_MAXTICKS ticks worth, by which point the level
1266 * will be stable.
1267 *
1268 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
1269 * arithmetic overflow in the fmeter_update() routine.
1270 *
1271 * Given the simple 32 bit integer arithmetic used, this meter works
1272 * best for reporting rates between one per millisecond (msec) and
1273 * one per 32 (approx) seconds.  At constant rates faster than one
1274 * per msec it maxes out at values just under 1,000,000.  At constant
1275 * rates between one per msec, and one per second it will stabilize
1276 * to a value N*1000, where N is the rate of events per second.
1277 * At constant rates between one per second and one per 32 seconds,
1278 * it will be choppy, moving up on the seconds that have an event,
1279 * and then decaying until the next event.  At rates slower than
1280 * about one in 32 seconds, it decays all the way back to zero between
1281 * each event.
1282 */
1283
1284#define FM_COEF 933             /* coefficient for half-life of 10 secs */
1285#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
1286#define FM_MAXCNT 1000000       /* limit cnt to avoid overflow */
1287#define FM_SCALE 1000           /* faux fixed point scale */
1288
1289/* Initialize a frequency meter */
1290static void fmeter_init(struct fmeter *fmp)
1291{
1292        fmp->cnt = 0;
1293        fmp->val = 0;
1294        fmp->time = 0;
1295        spin_lock_init(&fmp->lock);
1296}
1297
1298/* Internal meter update - process cnt events and update value */
1299static void fmeter_update(struct fmeter *fmp)
1300{
1301        time_t now = get_seconds();
1302        time_t ticks = now - fmp->time;
1303
1304        if (ticks == 0)
1305                return;
1306
1307        ticks = min(FM_MAXTICKS, ticks);
1308        while (ticks-- > 0)
1309                fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
1310        fmp->time = now;
1311
1312        fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
1313        fmp->cnt = 0;
1314}
1315
1316/* Process any previous ticks, then bump cnt by one (times scale). */
1317static void fmeter_markevent(struct fmeter *fmp)
1318{
1319        spin_lock(&fmp->lock);
1320        fmeter_update(fmp);
1321        fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
1322        spin_unlock(&fmp->lock);
1323}
1324
1325/* Process any previous ticks, then return current value. */
1326static int fmeter_getrate(struct fmeter *fmp)
1327{
1328        int val;
1329
1330        spin_lock(&fmp->lock);
1331        fmeter_update(fmp);
1332        val = fmp->val;
1333        spin_unlock(&fmp->lock);
1334        return val;
1335}
1336
1337/* Protected by cgroup_lock */
1338static cpumask_var_t cpus_attach;
1339
1340/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
1341static int cpuset_can_attach(struct cgroup_subsys *ss,
1342                             struct cgroup *cont, struct task_struct *tsk)
1343{
1344        struct cpuset *cs = cgroup_cs(cont);
1345
1346        if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
1347                return -ENOSPC;
1348
1349        /*
1350         * Kthreads bound to specific cpus cannot be moved to a new cpuset; we
1351         * cannot change their cpu affinity and isolating such threads by their
1352         * set of allowed nodes is unnecessary.  Thus, cpusets are not
1353         * applicable for such threads.  This prevents checking for success of
1354         * set_cpus_allowed_ptr() on all attached tasks before cpus_allowed may
1355         * be changed.
1356         */
1357        if (tsk->flags & PF_THREAD_BOUND)
1358                return -EINVAL;
1359
1360        return security_task_setscheduler(tsk, 0, NULL);
1361}
1362
1363static void cpuset_attach(struct cgroup_subsys *ss,
1364                          struct cgroup *cont, struct cgroup *oldcont,
1365                          struct task_struct *tsk)
1366{
1367        nodemask_t from, to;
1368        struct mm_struct *mm;
1369        struct cpuset *cs = cgroup_cs(cont);
1370        struct cpuset *oldcs = cgroup_cs(oldcont);
1371        int err;
1372
1373        if (cs == &top_cpuset) {
1374                cpumask_copy(cpus_attach, cpu_possible_mask);
1375        } else {
1376                mutex_lock(&callback_mutex);
1377                guarantee_online_cpus(cs, cpus_attach);
1378                mutex_unlock(&callback_mutex);
1379        }
1380        err = set_cpus_allowed_ptr(tsk, cpus_attach);
1381        if (err)
1382                return;
1383
1384        from = oldcs->mems_allowed;
1385        to = cs->mems_allowed;
1386        mm = get_task_mm(tsk);
1387        if (mm) {
1388                mpol_rebind_mm(mm, &to);
1389                if (is_memory_migrate(cs))
1390                        cpuset_migrate_mm(mm, &from, &to);
1391                mmput(mm);
1392        }
1393}
1394
1395/* The various types of files and directories in a cpuset file system */
1396
1397typedef enum {
1398        FILE_MEMORY_MIGRATE,
1399        FILE_CPULIST,
1400        FILE_MEMLIST,
1401        FILE_CPU_EXCLUSIVE,
1402        FILE_MEM_EXCLUSIVE,
1403        FILE_MEM_HARDWALL,
1404        FILE_SCHED_LOAD_BALANCE,
1405        FILE_SCHED_RELAX_DOMAIN_LEVEL,
1406        FILE_MEMORY_PRESSURE_ENABLED,
1407        FILE_MEMORY_PRESSURE,
1408        FILE_SPREAD_PAGE,
1409        FILE_SPREAD_SLAB,
1410} cpuset_filetype_t;
1411
1412static int cpuset_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
1413{
1414        int retval = 0;
1415        struct cpuset *cs = cgroup_cs(cgrp);
1416        cpuset_filetype_t type = cft->private;
1417
1418        if (!cgroup_lock_live_group(cgrp))
1419                return -ENODEV;
1420
1421        switch (type) {
1422        case FILE_CPU_EXCLUSIVE:
1423                retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
1424                break;
1425        case FILE_MEM_EXCLUSIVE:
1426                retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
1427                break;
1428        case FILE_MEM_HARDWALL:
1429                retval = update_flag(CS_MEM_HARDWALL, cs, val);
1430                break;
1431        case FILE_SCHED_LOAD_BALANCE:
1432                retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1433                break;
1434        case FILE_MEMORY_MIGRATE:
1435                retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1436                break;
1437        case FILE_MEMORY_PRESSURE_ENABLED:
1438                cpuset_memory_pressure_enabled = !!val;
1439                break;
1440        case FILE_MEMORY_PRESSURE:
1441                retval = -EACCES;
1442                break;
1443        case FILE_SPREAD_PAGE:
1444                retval = update_flag(CS_SPREAD_PAGE, cs, val);
1445                cs->mems_generation = cpuset_mems_generation++;
1446                break;
1447        case FILE_SPREAD_SLAB:
1448                retval = update_flag(CS_SPREAD_SLAB, cs, val);
1449                cs->mems_generation = cpuset_mems_generation++;
1450                break;
1451        default:
1452                retval = -EINVAL;
1453                break;
1454        }
1455        cgroup_unlock();
1456        return retval;
1457}
1458
1459static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
1460{
1461        int retval = 0;
1462        struct cpuset *cs = cgroup_cs(cgrp);
1463        cpuset_filetype_t type = cft->private;
1464
1465        if (!cgroup_lock_live_group(cgrp))
1466                return -ENODEV;
1467
1468        switch (type) {
1469        case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1470                retval = update_relax_domain_level(cs, val);
1471                break;
1472        default:
1473                retval = -EINVAL;
1474                break;
1475        }
1476        cgroup_unlock();
1477        return retval;
1478}
1479
1480/*
1481 * Common handling for a write to a "cpus" or "mems" file.
1482 */
1483static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
1484                                const char *buf)
1485{
1486        int retval = 0;
1487        struct cpuset *cs = cgroup_cs(cgrp);
1488        struct cpuset *trialcs;
1489
1490        if (!cgroup_lock_live_group(cgrp))
1491                return -ENODEV;
1492
1493        trialcs = alloc_trial_cpuset(cs);
1494        if (!trialcs)
1495                return -ENOMEM;
1496
1497        switch (cft->private) {
1498        case FILE_CPULIST:
1499                retval = update_cpumask(cs, trialcs, buf);
1500                break;
1501        case FILE_MEMLIST:
1502                retval = update_nodemask(cs, trialcs, buf);
1503                break;
1504        default:
1505                retval = -EINVAL;
1506                break;
1507        }
1508
1509        free_trial_cpuset(trialcs);
1510        cgroup_unlock();
1511        return retval;
1512}
1513
1514/*
1515 * These ascii lists should be read in a single call, by using a user
1516 * buffer large enough to hold the entire map.  If read in smaller
1517 * chunks, there is no guarantee of atomicity.  Since the display format
1518 * used, list of ranges of sequential numbers, is variable length,
1519 * and since these maps can change value dynamically, one could read
1520 * gibberish by doing partial reads while a list was changing.
1521 * A single large read to a buffer that crosses a page boundary is
1522 * ok, because the result being copied to user land is not recomputed
1523 * across a page fault.
1524 */
1525
1526static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
1527{
1528        int ret;
1529
1530        mutex_lock(&callback_mutex);
1531        ret = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed);
1532        mutex_unlock(&callback_mutex);
1533
1534        return ret;
1535}
1536
1537static int cpuset_sprintf_memlist(char *page, struct cpuset *cs)
1538{
1539        nodemask_t mask;
1540
1541        mutex_lock(&callback_mutex);
1542        mask = cs->mems_allowed;
1543        mutex_unlock(&callback_mutex);
1544
1545        return nodelist_scnprintf(page, PAGE_SIZE, mask);
1546}
1547
1548static ssize_t cpuset_common_file_read(struct cgroup *cont,
1549                                       struct cftype *cft,
1550                                       struct file *file,
1551                                       char __user *buf,
1552                                       size_t nbytes, loff_t *ppos)
1553{
1554        struct cpuset *cs = cgroup_cs(cont);
1555        cpuset_filetype_t type = cft->private;
1556        char *page;
1557        ssize_t retval = 0;
1558        char *s;
1559
1560        if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
1561                return -ENOMEM;
1562
1563        s = page;
1564
1565        switch (type) {
1566        case FILE_CPULIST:
1567                s += cpuset_sprintf_cpulist(s, cs);
1568                break;
1569        case FILE_MEMLIST:
1570                s += cpuset_sprintf_memlist(s, cs);
1571                break;
1572        default:
1573                retval = -EINVAL;
1574                goto out;
1575        }
1576        *s++ = '\n';
1577
1578        retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
1579out:
1580        free_page((unsigned long)page);
1581        return retval;
1582}
1583
1584static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft)
1585{
1586        struct cpuset *cs = cgroup_cs(cont);
1587        cpuset_filetype_t type = cft->private;
1588        switch (type) {
1589        case FILE_CPU_EXCLUSIVE:
1590                return is_cpu_exclusive(cs);
1591        case FILE_MEM_EXCLUSIVE:
1592                return is_mem_exclusive(cs);
1593        case FILE_MEM_HARDWALL:
1594                return is_mem_hardwall(cs);
1595        case FILE_SCHED_LOAD_BALANCE:
1596                return is_sched_load_balance(cs);
1597        case FILE_MEMORY_MIGRATE:
1598                return is_memory_migrate(cs);
1599        case FILE_MEMORY_PRESSURE_ENABLED:
1600                return cpuset_memory_pressure_enabled;
1601        case FILE_MEMORY_PRESSURE:
1602                return fmeter_getrate(&cs->fmeter);
1603        case FILE_SPREAD_PAGE:
1604                return is_spread_page(cs);
1605        case FILE_SPREAD_SLAB:
1606                return is_spread_slab(cs);
1607        default:
1608                BUG();
1609        }
1610
1611        /* Unreachable but makes gcc happy */
1612        return 0;
1613}
1614
1615static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)
1616{
1617        struct cpuset *cs = cgroup_cs(cont);
1618        cpuset_filetype_t type = cft->private;
1619        switch (type) {
1620        case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1621                return cs->relax_domain_level;
1622        default:
1623                BUG();
1624        }
1625
1626        /* Unrechable but makes gcc happy */
1627        return 0;
1628}
1629
1630
1631/*
1632 * for the common functions, 'private' gives the type of file
1633 */
1634
1635static struct cftype files[] = {
1636        {
1637                .name = "cpus",
1638                .read = cpuset_common_file_read,
1639                .write_string = cpuset_write_resmask,
1640                .max_write_len = (100U + 6 * NR_CPUS),
1641                .private = FILE_CPULIST,
1642        },
1643
1644        {
1645                .name = "mems",
1646                .read = cpuset_common_file_read,
1647                .write_string = cpuset_write_resmask,
1648                .max_write_len = (100U + 6 * MAX_NUMNODES),
1649                .private = FILE_MEMLIST,
1650        },
1651
1652        {
1653                .name = "cpu_exclusive",
1654                .read_u64 = cpuset_read_u64,
1655                .write_u64 = cpuset_write_u64,
1656                .private = FILE_CPU_EXCLUSIVE,
1657        },
1658
1659        {
1660                .name = "mem_exclusive",
1661                .read_u64 = cpuset_read_u64,
1662                .write_u64 = cpuset_write_u64,
1663                .private = FILE_MEM_EXCLUSIVE,
1664        },
1665
1666        {
1667                .name = "mem_hardwall",
1668                .read_u64 = cpuset_read_u64,
1669                .write_u64 = cpuset_write_u64,
1670                .private = FILE_MEM_HARDWALL,
1671        },
1672
1673        {
1674                .name = "sched_load_balance",
1675                .read_u64 = cpuset_read_u64,
1676                .write_u64 = cpuset_write_u64,
1677                .private = FILE_SCHED_LOAD_BALANCE,
1678        },
1679
1680        {
1681                .name = "sched_relax_domain_level",
1682                .read_s64 = cpuset_read_s64,
1683                .write_s64 = cpuset_write_s64,
1684                .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
1685        },
1686
1687        {
1688                .name = "memory_migrate",
1689                .read_u64 = cpuset_read_u64,
1690                .write_u64 = cpuset_write_u64,
1691                .private = FILE_MEMORY_MIGRATE,
1692        },
1693
1694        {
1695                .name = "memory_pressure",
1696                .read_u64 = cpuset_read_u64,
1697                .write_u64 = cpuset_write_u64,
1698                .private = FILE_MEMORY_PRESSURE,
1699                .mode = S_IRUGO,
1700        },
1701
1702        {
1703                .name = "memory_spread_page",
1704                .read_u64 = cpuset_read_u64,
1705                .write_u64 = cpuset_write_u64,
1706                .private = FILE_SPREAD_PAGE,
1707        },
1708
1709        {
1710                .name = "memory_spread_slab",
1711                .read_u64 = cpuset_read_u64,
1712                .write_u64 = cpuset_write_u64,
1713                .private = FILE_SPREAD_SLAB,
1714        },
1715};
1716
1717static struct cftype cft_memory_pressure_enabled = {
1718        .name = "memory_pressure_enabled",
1719        .read_u64 = cpuset_read_u64,
1720        .write_u64 = cpuset_write_u64,
1721        .private = FILE_MEMORY_PRESSURE_ENABLED,
1722};
1723
1724static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
1725{
1726        int err;
1727
1728        err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
1729        if (err)
1730                return err;
1731        /* memory_pressure_enabled is in root cpuset only */
1732        if (!cont->parent)
1733                err = cgroup_add_file(cont, ss,
1734                                      &cft_memory_pressure_enabled);
1735        return err;
1736}
1737
1738/*
1739 * post_clone() is called at the end of cgroup_clone().
1740 * 'cgroup' was just created automatically as a result of
1741 * a cgroup_clone(), and the current task is about to
1742 * be moved into 'cgroup'.
1743 *
1744 * Currently we refuse to set up the cgroup - thereby
1745 * refusing the task to be entered, and as a result refusing
1746 * the sys_unshare() or clone() which initiated it - if any
1747 * sibling cpusets have exclusive cpus or mem.
1748 *
1749 * If this becomes a problem for some users who wish to
1750 * allow that scenario, then cpuset_post_clone() could be
1751 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1752 * (and likewise for mems) to the new cgroup. Called with cgroup_mutex
1753 * held.
1754 */
1755static void cpuset_post_clone(struct cgroup_subsys *ss,
1756                              struct cgroup *cgroup)
1757{
1758        struct cgroup *parent, *child;
1759        struct cpuset *cs, *parent_cs;
1760
1761        parent = cgroup->parent;
1762        list_for_each_entry(child, &parent->children, sibling) {
1763                cs = cgroup_cs(child);
1764                if (is_mem_exclusive(cs) || is_cpu_exclusive(cs))
1765                        return;
1766        }
1767        cs = cgroup_cs(cgroup);
1768        parent_cs = cgroup_cs(parent);
1769
1770        cs->mems_allowed = parent_cs->mems_allowed;
1771        cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed);
1772        return;
1773}
1774
1775/*
1776 *      cpuset_create - create a cpuset
1777 *      ss:     cpuset cgroup subsystem
1778 *      cont:   control group that the new cpuset will be part of
1779 */
1780
1781static struct cgroup_subsys_state *cpuset_create(
1782        struct cgroup_subsys *ss,
1783        struct cgroup *cont)
1784{
1785        struct cpuset *cs;
1786        struct cpuset *parent;
1787
1788        if (!cont->parent) {
1789                /* This is early initialization for the top cgroup */
1790                top_cpuset.mems_generation = cpuset_mems_generation++;
1791                return &top_cpuset.css;
1792        }
1793        parent = cgroup_cs(cont->parent);
1794        cs = kmalloc(sizeof(*cs), GFP_KERNEL);
1795        if (!cs)
1796                return ERR_PTR(-ENOMEM);
1797        if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
1798                kfree(cs);
1799                return ERR_PTR(-ENOMEM);
1800        }
1801
1802        cpuset_update_task_memory_state();
1803        cs->flags = 0;
1804        if (is_spread_page(parent))
1805                set_bit(CS_SPREAD_PAGE, &cs->flags);
1806        if (is_spread_slab(parent))
1807                set_bit(CS_SPREAD_SLAB, &cs->flags);
1808        set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1809        cpumask_clear(cs->cpus_allowed);
1810        nodes_clear(cs->mems_allowed);
1811        cs->mems_generation = cpuset_mems_generation++;
1812        fmeter_init(&cs->fmeter);
1813        cs->relax_domain_level = -1;
1814
1815        cs->parent = parent;
1816        number_of_cpusets++;
1817        return &cs->css ;
1818}
1819
1820/*
1821 * If the cpuset being removed has its flag 'sched_load_balance'
1822 * enabled, then simulate turning sched_load_balance off, which
1823 * will call async_rebuild_sched_domains().
1824 */
1825
1826static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
1827{
1828        struct cpuset *cs = cgroup_cs(cont);
1829
1830        cpuset_update_task_memory_state();
1831
1832        if (is_sched_load_balance(cs))
1833                update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
1834
1835        number_of_cpusets--;
1836        free_cpumask_var(cs->cpus_allowed);
1837        kfree(cs);
1838}
1839
1840struct cgroup_subsys cpuset_subsys = {
1841        .name = "cpuset",
1842        .create = cpuset_create,
1843        .destroy = cpuset_destroy,
1844        .can_attach = cpuset_can_attach,
1845        .attach = cpuset_attach,
1846        .populate = cpuset_populate,
1847        .post_clone = cpuset_post_clone,
1848        .subsys_id = cpuset_subsys_id,
1849        .early_init = 1,
1850};
1851
1852/*
1853 * cpuset_init_early - just enough so that the calls to
1854 * cpuset_update_task_memory_state() in early init code
1855 * are harmless.
1856 */
1857
1858int __init cpuset_init_early(void)
1859{
1860        alloc_bootmem_cpumask_var(&top_cpuset.cpus_allowed);
1861
1862        top_cpuset.mems_generation = cpuset_mems_generation++;
1863        return 0;
1864}
1865
1866
1867/**
1868 * cpuset_init - initialize cpusets at system boot
1869 *
1870 * Description: Initialize top_cpuset and the cpuset internal file system,
1871 **/
1872
1873int __init cpuset_init(void)
1874{
1875        int err = 0;
1876
1877        cpumask_setall(top_cpuset.cpus_allowed);
1878        nodes_setall(top_cpuset.mems_allowed);
1879
1880        fmeter_init(&top_cpuset.fmeter);
1881        top_cpuset.mems_generation = cpuset_mems_generation++;
1882        set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1883        top_cpuset.relax_domain_level = -1;
1884
1885        err = register_filesystem(&cpuset_fs_type);
1886        if (err < 0)
1887                return err;
1888
1889        if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
1890                BUG();
1891
1892        number_of_cpusets = 1;
1893        return 0;
1894}
1895
1896/**
1897 * cpuset_do_move_task - move a given task to another cpuset
1898 * @tsk: pointer to task_struct the task to move
1899 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
1900 *
1901 * Called by cgroup_scan_tasks() for each task in a cgroup.
1902 * Return nonzero to stop the walk through the tasks.
1903 */
1904static void cpuset_do_move_task(struct task_struct *tsk,
1905                                struct cgroup_scanner *scan)
1906{
1907        struct cgroup *new_cgroup = scan->data;
1908
1909        cgroup_attach_task(new_cgroup, tsk);
1910}
1911
1912/**
1913 * move_member_tasks_to_cpuset - move tasks from one cpuset to another
1914 * @from: cpuset in which the tasks currently reside
1915 * @to: cpuset to which the tasks will be moved
1916 *
1917 * Called with cgroup_mutex held
1918 * callback_mutex must not be held, as cpuset_attach() will take it.
1919 *
1920 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
1921 * calling callback functions for each.
1922 */
1923static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to)
1924{
1925        struct cgroup_scanner scan;
1926
1927        scan.cg = from->css.cgroup;
1928        scan.test_task = NULL; /* select all tasks in cgroup */
1929        scan.process_task = cpuset_do_move_task;
1930        scan.heap = NULL;
1931        scan.data = to->css.cgroup;
1932
1933        if (cgroup_scan_tasks(&scan))
1934                printk(KERN_ERR "move_member_tasks_to_cpuset: "
1935                                "cgroup_scan_tasks failed\n");
1936}
1937
1938/*
1939 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
1940 * or memory nodes, we need to walk over the cpuset hierarchy,
1941 * removing that CPU or node from all cpusets.  If this removes the
1942 * last CPU or node from a cpuset, then move the tasks in the empty
1943 * cpuset to its next-highest non-empty parent.
1944 *
1945 * Called with cgroup_mutex held
1946 * callback_mutex must not be held, as cpuset_attach() will take it.
1947 */
1948static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
1949{
1950        struct cpuset *parent;
1951
1952        /*
1953         * The cgroup's css_sets list is in use if there are tasks
1954         * in the cpuset; the list is empty if there are none;
1955         * the cs->css.refcnt seems always 0.
1956         */
1957        if (list_empty(&cs->css.cgroup->css_sets))
1958                return;
1959
1960        /*
1961         * Find its next-highest non-empty parent, (top cpuset
1962         * has online cpus, so can't be empty).
1963         */
1964        parent = cs->parent;
1965        while (cpumask_empty(parent->cpus_allowed) ||
1966                        nodes_empty(parent->mems_allowed))
1967                parent = parent->parent;
1968
1969        move_member_tasks_to_cpuset(cs, parent);
1970}
1971
1972/*
1973 * Walk the specified cpuset subtree and look for empty cpusets.
1974 * The tasks of such cpuset must be moved to a parent cpuset.
1975 *
1976 * Called with cgroup_mutex held.  We take callback_mutex to modify
1977 * cpus_allowed and mems_allowed.
1978 *
1979 * This walk processes the tree from top to bottom, completing one layer
1980 * before dropping down to the next.  It always processes a node before
1981 * any of its children.
1982 *
1983 * For now, since we lack memory hot unplug, we'll never see a cpuset
1984 * that has tasks along with an empty 'mems'.  But if we did see such
1985 * a cpuset, we'd handle it just like we do if its 'cpus' was empty.
1986 */
1987static void scan_for_empty_cpusets(struct cpuset *root)
1988{
1989        LIST_HEAD(queue);
1990        struct cpuset *cp;      /* scans cpusets being updated */
1991        struct cpuset *child;   /* scans child cpusets of cp */
1992        struct cgroup *cont;
1993        nodemask_t oldmems;
1994
1995        list_add_tail((struct list_head *)&root->stack_list, &queue);
1996
1997        while (!list_empty(&queue)) {
1998                cp = list_first_entry(&queue, struct cpuset, stack_list);
1999                list_del(queue.next);
2000                list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
2001                        child = cgroup_cs(cont);
2002                        list_add_tail(&child->stack_list, &queue);
2003                }
2004
2005                /* Continue past cpusets with all cpus, mems online */
2006                if (cpumask_subset(cp->cpus_allowed, cpu_online_mask) &&
2007                    nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
2008                        continue;
2009
2010                oldmems = cp->mems_allowed;
2011
2012                /* Remove offline cpus and mems from this cpuset. */
2013                mutex_lock(&callback_mutex);
2014                cpumask_and(cp->cpus_allowed, cp->cpus_allowed,
2015                            cpu_online_mask);
2016                nodes_and(cp->mems_allowed, cp->mems_allowed,
2017                                                node_states[N_HIGH_MEMORY]);
2018                mutex_unlock(&callback_mutex);
2019
2020                /* Move tasks from the empty cpuset to a parent */
2021                if (cpumask_empty(cp->cpus_allowed) ||
2022                     nodes_empty(cp->mems_allowed))
2023                        remove_tasks_in_empty_cpuset(cp);
2024                else {
2025                        update_tasks_cpumask(cp, NULL);
2026                        update_tasks_nodemask(cp, &oldmems, NULL);
2027                }
2028        }
2029}
2030
2031/*
2032 * The top_cpuset tracks what CPUs and Memory Nodes are online,
2033 * period.  This is necessary in order to make cpusets transparent
2034 * (of no affect) on systems that are actively using CPU hotplug
2035 * but making no active use of cpusets.
2036 *
2037 * This routine ensures that top_cpuset.cpus_allowed tracks
2038 * cpu_online_map on each CPU hotplug (cpuhp) event.
2039 *
2040 * Called within get_online_cpus().  Needs to call cgroup_lock()
2041 * before calling generate_sched_domains().
2042 */
2043static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
2044                                unsigned long phase, void *unused_cpu)
2045{
2046        struct sched_domain_attr *attr;
2047        struct cpumask *doms;
2048        int ndoms;
2049
2050        switch (phase) {
2051        case CPU_ONLINE:
2052        case CPU_ONLINE_FROZEN:
2053        case CPU_DEAD:
2054        case CPU_DEAD_FROZEN:
2055                break;
2056
2057        default:
2058                return NOTIFY_DONE;
2059        }
2060
2061        cgroup_lock();
2062        mutex_lock(&callback_mutex);
2063        cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask);
2064        mutex_unlock(&callback_mutex);
2065        scan_for_empty_cpusets(&top_cpuset);
2066        ndoms = generate_sched_domains(&doms, &attr);
2067        cgroup_unlock();
2068
2069        /* Have scheduler rebuild the domains */
2070        partition_sched_domains(ndoms, doms, attr);
2071
2072        return NOTIFY_OK;
2073}
2074
2075#ifdef CONFIG_MEMORY_HOTPLUG
2076/*
2077 * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
2078 * Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
2079 * See also the previous routine cpuset_track_online_cpus().
2080 */
2081static int cpuset_track_online_nodes(struct notifier_block *self,
2082                                unsigned long action, void *arg)
2083{
2084        cgroup_lock();
2085        switch (action) {
2086        case MEM_ONLINE:
2087        case MEM_OFFLINE:
2088                mutex_lock(&callback_mutex);
2089                top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2090                mutex_unlock(&callback_mutex);
2091                if (action == MEM_OFFLINE)
2092                        scan_for_empty_cpusets(&top_cpuset);
2093                break;
2094        default:
2095                break;
2096        }
2097        cgroup_unlock();
2098        return NOTIFY_OK;
2099}
2100#endif
2101
2102/**
2103 * cpuset_init_smp - initialize cpus_allowed
2104 *
2105 * Description: Finish top cpuset after cpu, node maps are initialized
2106 **/
2107
2108void __init cpuset_init_smp(void)
2109{
2110        cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask);
2111        top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2112
2113        hotcpu_notifier(cpuset_track_online_cpus, 0);
2114        hotplug_memory_notifier(cpuset_track_online_nodes, 10);
2115
2116        cpuset_wq = create_singlethread_workqueue("cpuset");
2117        BUG_ON(!cpuset_wq);
2118}
2119
2120/**
2121 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
2122 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2123 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
2124 *
2125 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
2126 * attached to the specified @tsk.  Guaranteed to return some non-empty
2127 * subset of cpu_online_map, even if this means going outside the
2128 * tasks cpuset.
2129 **/
2130
2131void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
2132{
2133        mutex_lock(&callback_mutex);
2134        cpuset_cpus_allowed_locked(tsk, pmask);
2135        mutex_unlock(&callback_mutex);
2136}
2137
2138/**
2139 * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset.
2140 * Must be called with callback_mutex held.
2141 **/
2142void cpuset_cpus_allowed_locked(struct task_struct *tsk, struct cpumask *pmask)
2143{
2144        task_lock(tsk);
2145        guarantee_online_cpus(task_cs(tsk), pmask);
2146        task_unlock(tsk);
2147}
2148
2149void cpuset_init_current_mems_allowed(void)
2150{
2151        nodes_setall(current->mems_allowed);
2152}
2153
2154/**
2155 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
2156 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
2157 *
2158 * Description: Returns the nodemask_t mems_allowed of the cpuset
2159 * attached to the specified @tsk.  Guaranteed to return some non-empty
2160 * subset of node_states[N_HIGH_MEMORY], even if this means going outside the
2161 * tasks cpuset.
2162 **/
2163
2164nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
2165{
2166        nodemask_t mask;
2167
2168        mutex_lock(&callback_mutex);
2169        task_lock(tsk);
2170        guarantee_online_mems(task_cs(tsk), &mask);
2171        task_unlock(tsk);
2172        mutex_unlock(&callback_mutex);
2173
2174        return mask;
2175}
2176
2177/**
2178 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
2179 * @nodemask: the nodemask to be checked
2180 *
2181 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
2182 */
2183int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
2184{
2185        return nodes_intersects(*nodemask, current->mems_allowed);
2186}
2187
2188/*
2189 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
2190 * mem_hardwall ancestor to the specified cpuset.  Call holding
2191 * callback_mutex.  If no ancestor is mem_exclusive or mem_hardwall
2192 * (an unusual configuration), then returns the root cpuset.
2193 */
2194static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
2195{
2196        while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent)
2197                cs = cs->parent;
2198        return cs;
2199}
2200
2201/**
2202 * cpuset_node_allowed_softwall - Can we allocate on a memory node?
2203 * @node: is this an allowed node?
2204 * @gfp_mask: memory allocation flags
2205 *
2206 * If we're in interrupt, yes, we can always allocate.  If __GFP_THISNODE is
2207 * set, yes, we can always allocate.  If node is in our task's mems_allowed,
2208 * yes.  If it's not a __GFP_HARDWALL request and this node is in the nearest
2209 * hardwalled cpuset ancestor to this task's cpuset, yes.  If the task has been
2210 * OOM killed and has access to memory reserves as specified by the TIF_MEMDIE
2211 * flag, yes.
2212 * Otherwise, no.
2213 *
2214 * If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to
2215 * cpuset_node_allowed_hardwall().  Otherwise, cpuset_node_allowed_softwall()
2216 * might sleep, and might allow a node from an enclosing cpuset.
2217 *
2218 * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
2219 * cpusets, and never sleeps.
2220 *
2221 * The __GFP_THISNODE placement logic is really handled elsewhere,
2222 * by forcibly using a zonelist starting at a specified node, and by
2223 * (in get_page_from_freelist()) refusing to consider the zones for
2224 * any node on the zonelist except the first.  By the time any such
2225 * calls get to this routine, we should just shut up and say 'yes'.
2226 *
2227 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2228 * and do not allow allocations outside the current tasks cpuset
2229 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2230 * GFP_KERNEL allocations are not so marked, so can escape to the
2231 * nearest enclosing hardwalled ancestor cpuset.
2232 *
2233 * Scanning up parent cpusets requires callback_mutex.  The
2234 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
2235 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
2236 * current tasks mems_allowed came up empty on the first pass over
2237 * the zonelist.  So only GFP_KERNEL allocations, if all nodes in the
2238 * cpuset are short of memory, might require taking the callback_mutex
2239 * mutex.
2240 *
2241 * The first call here from mm/page_alloc:get_page_from_freelist()
2242 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
2243 * so no allocation on a node outside the cpuset is allowed (unless
2244 * in interrupt, of course).
2245 *
2246 * The second pass through get_page_from_freelist() doesn't even call
2247 * here for GFP_ATOMIC calls.  For those calls, the __alloc_pages()
2248 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
2249 * in alloc_flags.  That logic and the checks below have the combined
2250 * affect that:
2251 *      in_interrupt - any node ok (current task context irrelevant)
2252 *      GFP_ATOMIC   - any node ok
2253 *      TIF_MEMDIE   - any node ok
2254 *      GFP_KERNEL   - any node in enclosing hardwalled cpuset ok
2255 *      GFP_USER     - only nodes in current tasks mems allowed ok.
2256 *
2257 * Rule:
2258 *    Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
2259 *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
2260 *    the code that might scan up ancestor cpusets and sleep.
2261 */
2262int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
2263{
2264        const struct cpuset *cs;        /* current cpuset ancestors */
2265        int allowed;                    /* is allocation in zone z allowed? */
2266
2267        if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2268                return 1;
2269        might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2270        if (node_isset(node, current->mems_allowed))
2271                return 1;
2272        /*
2273         * Allow tasks that have access to memory reserves because they have
2274         * been OOM killed to get memory anywhere.
2275         */
2276        if (unlikely(test_thread_flag(TIF_MEMDIE)))
2277                return 1;
2278        if (gfp_mask & __GFP_HARDWALL)  /* If hardwall request, stop here */
2279                return 0;
2280
2281        if (current->flags & PF_EXITING) /* Let dying task have memory */
2282                return 1;
2283
2284        /* Not hardwall and node outside mems_allowed: scan up cpusets */
2285        mutex_lock(&callback_mutex);
2286
2287        task_lock(current);
2288        cs = nearest_hardwall_ancestor(task_cs(current));
2289        task_unlock(current);
2290
2291        allowed = node_isset(node, cs->mems_allowed);
2292        mutex_unlock(&callback_mutex);
2293        return allowed;
2294}
2295
2296/*
2297 * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
2298 * @node: is this an allowed node?
2299 * @gfp_mask: memory allocation flags
2300 *
2301 * If we're in interrupt, yes, we can always allocate.  If __GFP_THISNODE is
2302 * set, yes, we can always allocate.  If node is in our task's mems_allowed,
2303 * yes.  If the task has been OOM killed and has access to memory reserves as
2304 * specified by the TIF_MEMDIE flag, yes.
2305 * Otherwise, no.
2306 *
2307 * The __GFP_THISNODE placement logic is really handled elsewhere,
2308 * by forcibly using a zonelist starting at a specified node, and by
2309 * (in get_page_from_freelist()) refusing to consider the zones for
2310 * any node on the zonelist except the first.  By the time any such
2311 * calls get to this routine, we should just shut up and say 'yes'.
2312 *
2313 * Unlike the cpuset_node_allowed_softwall() variant, above,
2314 * this variant requires that the node be in the current task's
2315 * mems_allowed or that we're in interrupt.  It does not scan up the
2316 * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
2317 * It never sleeps.
2318 */
2319int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
2320{
2321        if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2322                return 1;
2323        if (node_isset(node, current->mems_allowed))
2324                return 1;
2325        /*
2326         * Allow tasks that have access to memory reserves because they have
2327         * been OOM killed to get memory anywhere.
2328         */
2329        if (unlikely(test_thread_flag(TIF_MEMDIE)))
2330                return 1;
2331        return 0;
2332}
2333
2334/**
2335 * cpuset_lock - lock out any changes to cpuset structures
2336 *
2337 * The out of memory (oom) code needs to mutex_lock cpusets
2338 * from being changed while it scans the tasklist looking for a
2339 * task in an overlapping cpuset.  Expose callback_mutex via this
2340 * cpuset_lock() routine, so the oom code can lock it, before
2341 * locking the task list.  The tasklist_lock is a spinlock, so
2342 * must be taken inside callback_mutex.
2343 */
2344
2345void cpuset_lock(void)
2346{
2347        mutex_lock(&callback_mutex);
2348}
2349
2350/**
2351 * cpuset_unlock - release lock on cpuset changes
2352 *
2353 * Undo the lock taken in a previous cpuset_lock() call.
2354 */
2355
2356void cpuset_unlock(void)
2357{
2358        mutex_unlock(&callback_mutex);
2359}
2360
2361/**
2362 * cpuset_mem_spread_node() - On which node to begin search for a page
2363 *
2364 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
2365 * tasks in a cpuset with is_spread_page or is_spread_slab set),
2366 * and if the memory allocation used cpuset_mem_spread_node()
2367 * to determine on which node to start looking, as it will for
2368 * certain page cache or slab cache pages such as used for file
2369 * system buffers and inode caches, then instead of starting on the
2370 * local node to look for a free page, rather spread the starting
2371 * node around the tasks mems_allowed nodes.
2372 *
2373 * We don't have to worry about the returned node being offline
2374 * because "it can't happen", and even if it did, it would be ok.
2375 *
2376 * The routines calling guarantee_online_mems() are careful to
2377 * only set nodes in task->mems_allowed that are online.  So it
2378 * should not be possible for the following code to return an
2379 * offline node.  But if it did, that would be ok, as this routine
2380 * is not returning the node where the allocation must be, only
2381 * the node where the search should start.  The zonelist passed to
2382 * __alloc_pages() will include all nodes.  If the slab allocator
2383 * is passed an offline node, it will fall back to the local node.
2384 * See kmem_cache_alloc_node().
2385 */
2386
2387int cpuset_mem_spread_node(void)
2388{
2389        int node;
2390
2391        node = next_node(current->cpuset_mem_spread_rotor, current->mems_allowed);
2392        if (node == MAX_NUMNODES)
2393                node = first_node(current->mems_allowed);
2394        current->cpuset_mem_spread_rotor = node;
2395        return node;
2396}
2397EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
2398
2399/**
2400 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
2401 * @tsk1: pointer to task_struct of some task.
2402 * @tsk2: pointer to task_struct of some other task.
2403 *
2404 * Description: Return true if @tsk1's mems_allowed intersects the
2405 * mems_allowed of @tsk2.  Used by the OOM killer to determine if
2406 * one of the task's memory usage might impact the memory available
2407 * to the other.
2408 **/
2409
2410int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
2411                                   const struct task_struct *tsk2)
2412{
2413        return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2414}
2415
2416/**
2417 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
2418 * @task: pointer to task_struct of some task.
2419 *
2420 * Description: Prints @task's name, cpuset name, and cached copy of its
2421 * mems_allowed to the kernel log.  Must hold task_lock(task) to allow
2422 * dereferencing task_cs(task).
2423 */
2424void cpuset_print_task_mems_allowed(struct task_struct *tsk)
2425{
2426        struct dentry *dentry;
2427
2428        dentry = task_cs(tsk)->css.cgroup->dentry;
2429        spin_lock(&cpuset_buffer_lock);
2430        snprintf(cpuset_name, CPUSET_NAME_LEN,
2431                 dentry ? (const char *)dentry->d_name.name : "/");
2432        nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
2433                           tsk->mems_allowed);
2434        printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
2435               tsk->comm, cpuset_name, cpuset_nodelist);
2436        spin_unlock(&cpuset_buffer_lock);
2437}
2438
2439/*
2440 * Collection of memory_pressure is suppressed unless
2441 * this flag is enabled by writing "1" to the special
2442 * cpuset file 'memory_pressure_enabled' in the root cpuset.
2443 */
2444
2445int cpuset_memory_pressure_enabled __read_mostly;
2446
2447/**
2448 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
2449 *
2450 * Keep a running average of the rate of synchronous (direct)
2451 * page reclaim efforts initiated by tasks in each cpuset.
2452 *
2453 * This represents the rate at which some task in the cpuset
2454 * ran low on memory on all nodes it was allowed to use, and
2455 * had to enter the kernels page reclaim code in an effort to
2456 * create more free memory by tossing clean pages or swapping
2457 * or writing dirty pages.
2458 *
2459 * Display to user space in the per-cpuset read-only file
2460 * "memory_pressure".  Value displayed is an integer
2461 * representing the recent rate of entry into the synchronous
2462 * (direct) page reclaim by any task attached to the cpuset.
2463 **/
2464
2465void __cpuset_memory_pressure_bump(void)
2466{
2467        task_lock(current);
2468        fmeter_markevent(&task_cs(current)->fmeter);
2469        task_unlock(current);
2470}
2471
2472#ifdef CONFIG_PROC_PID_CPUSET
2473/*
2474 * proc_cpuset_show()
2475 *  - Print tasks cpuset path into seq_file.
2476 *  - Used for /proc/<pid>/cpuset.
2477 *  - No need to task_lock(tsk) on this tsk->cpuset reference, as it
2478 *    doesn't really matter if tsk->cpuset changes after we read it,
2479 *    and we take cgroup_mutex, keeping cpuset_attach() from changing it
2480 *    anyway.
2481 */
2482static int proc_cpuset_show(struct seq_file *m, void *unused_v)
2483{
2484        struct pid *pid;
2485        struct task_struct *tsk;
2486        char *buf;
2487        struct cgroup_subsys_state *css;
2488        int retval;
2489
2490        retval = -ENOMEM;
2491        buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
2492        if (!buf)
2493                goto out;
2494
2495        retval = -ESRCH;
2496        pid = m->private;
2497        tsk = get_pid_task(pid, PIDTYPE_PID);
2498        if (!tsk)
2499                goto out_free;
2500
2501        retval = -EINVAL;
2502        cgroup_lock();
2503        css = task_subsys_state(tsk, cpuset_subsys_id);
2504        retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
2505        if (retval < 0)
2506                goto out_unlock;
2507        seq_puts(m, buf);
2508        seq_putc(m, '\n');
2509out_unlock:
2510        cgroup_unlock();
2511        put_task_struct(tsk);
2512out_free:
2513        kfree(buf);
2514out:
2515        return retval;
2516}
2517
2518static int cpuset_open(struct inode *inode, struct file *file)
2519{
2520        struct pid *pid = PROC_I(inode)->pid;
2521        return single_open(file, proc_cpuset_show, pid);
2522}
2523
2524const struct file_operations proc_cpuset_operations = {
2525        .open           = cpuset_open,
2526        .read           = seq_read,
2527        .llseek         = seq_lseek,
2528        .release        = single_release,
2529};
2530#endif /* CONFIG_PROC_PID_CPUSET */
2531
2532/* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */
2533void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
2534{
2535        seq_printf(m, "Cpus_allowed:\t");
2536        seq_cpumask(m, &task->cpus_allowed);
2537        seq_printf(m, "\n");
2538        seq_printf(m, "Cpus_allowed_list:\t");
2539        seq_cpumask_list(m, &task->cpus_allowed);
2540        seq_printf(m, "\n");
2541        seq_printf(m, "Mems_allowed:\t");
2542        seq_nodemask(m, &task->mems_allowed);
2543        seq_printf(m, "\n");
2544        seq_printf(m, "Mems_allowed_list:\t");
2545        seq_nodemask_list(m, &task->mems_allowed);
2546        seq_printf(m, "\n");
2547}
2548