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/export.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/time64.h>
  55#include <linux/backing-dev.h>
  56#include <linux/sort.h>
  57
  58#include <asm/uaccess.h>
  59#include <linux/atomic.h>
  60#include <linux/mutex.h>
  61#include <linux/cgroup.h>
  62#include <linux/wait.h>
  63
  64DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key);
  65
  66/* See "Frequency meter" comments, below. */
  67
  68struct fmeter {
  69        int cnt;                /* unprocessed events count */
  70        int val;                /* most recent output value */
  71        time64_t time;          /* clock (secs) when val computed */
  72        spinlock_t lock;        /* guards read or write of above */
  73};
  74
  75struct cpuset {
  76        struct cgroup_subsys_state css;
  77
  78        unsigned long flags;            /* "unsigned long" so bitops work */
  79
  80        /*
  81         * On default hierarchy:
  82         *
  83         * The user-configured masks can only be changed by writing to
  84         * cpuset.cpus and cpuset.mems, and won't be limited by the
  85         * parent masks.
  86         *
  87         * The effective masks is the real masks that apply to the tasks
  88         * in the cpuset. They may be changed if the configured masks are
  89         * changed or hotplug happens.
  90         *
  91         * effective_mask == configured_mask & parent's effective_mask,
  92         * and if it ends up empty, it will inherit the parent's mask.
  93         *
  94         *
  95         * On legacy hierachy:
  96         *
  97         * The user-configured masks are always the same with effective masks.
  98         */
  99
 100        /* user-configured CPUs and Memory Nodes allow to tasks */
 101        cpumask_var_t cpus_allowed;
 102        nodemask_t mems_allowed;
 103
 104        /* effective CPUs and Memory Nodes allow to tasks */
 105        cpumask_var_t effective_cpus;
 106        nodemask_t effective_mems;
 107
 108        /*
 109         * This is old Memory Nodes tasks took on.
 110         *
 111         * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
 112         * - A new cpuset's old_mems_allowed is initialized when some
 113         *   task is moved into it.
 114         * - old_mems_allowed is used in cpuset_migrate_mm() when we change
 115         *   cpuset.mems_allowed and have tasks' nodemask updated, and
 116         *   then old_mems_allowed is updated to mems_allowed.
 117         */
 118        nodemask_t old_mems_allowed;
 119
 120        struct fmeter fmeter;           /* memory_pressure filter */
 121
 122        /*
 123         * Tasks are being attached to this cpuset.  Used to prevent
 124         * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
 125         */
 126        int attach_in_progress;
 127
 128        /* partition number for rebuild_sched_domains() */
 129        int pn;
 130
 131        /* for custom sched domain */
 132        int relax_domain_level;
 133};
 134
 135static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
 136{
 137        return css ? container_of(css, struct cpuset, css) : NULL;
 138}
 139
 140/* Retrieve the cpuset for a task */
 141static inline struct cpuset *task_cs(struct task_struct *task)
 142{
 143        return css_cs(task_css(task, cpuset_cgrp_id));
 144}
 145
 146static inline struct cpuset *parent_cs(struct cpuset *cs)
 147{
 148        return css_cs(cs->css.parent);
 149}
 150
 151#ifdef CONFIG_NUMA
 152static inline bool task_has_mempolicy(struct task_struct *task)
 153{
 154        return task->mempolicy;
 155}
 156#else
 157static inline bool task_has_mempolicy(struct task_struct *task)
 158{
 159        return false;
 160}
 161#endif
 162
 163
 164/* bits in struct cpuset flags field */
 165typedef enum {
 166        CS_ONLINE,
 167        CS_CPU_EXCLUSIVE,
 168        CS_MEM_EXCLUSIVE,
 169        CS_MEM_HARDWALL,
 170        CS_MEMORY_MIGRATE,
 171        CS_SCHED_LOAD_BALANCE,
 172        CS_SPREAD_PAGE,
 173        CS_SPREAD_SLAB,
 174} cpuset_flagbits_t;
 175
 176/* convenient tests for these bits */
 177static inline bool is_cpuset_online(const struct cpuset *cs)
 178{
 179        return test_bit(CS_ONLINE, &cs->flags);
 180}
 181
 182static inline int is_cpu_exclusive(const struct cpuset *cs)
 183{
 184        return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
 185}
 186
 187static inline int is_mem_exclusive(const struct cpuset *cs)
 188{
 189        return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
 190}
 191
 192static inline int is_mem_hardwall(const struct cpuset *cs)
 193{
 194        return test_bit(CS_MEM_HARDWALL, &cs->flags);
 195}
 196
 197static inline int is_sched_load_balance(const struct cpuset *cs)
 198{
 199        return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
 200}
 201
 202static inline int is_memory_migrate(const struct cpuset *cs)
 203{
 204        return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
 205}
 206
 207static inline int is_spread_page(const struct cpuset *cs)
 208{
 209        return test_bit(CS_SPREAD_PAGE, &cs->flags);
 210}
 211
 212static inline int is_spread_slab(const struct cpuset *cs)
 213{
 214        return test_bit(CS_SPREAD_SLAB, &cs->flags);
 215}
 216
 217static struct cpuset top_cpuset = {
 218        .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
 219                  (1 << CS_MEM_EXCLUSIVE)),
 220};
 221
 222/**
 223 * cpuset_for_each_child - traverse online children of a cpuset
 224 * @child_cs: loop cursor pointing to the current child
 225 * @pos_css: used for iteration
 226 * @parent_cs: target cpuset to walk children of
 227 *
 228 * Walk @child_cs through the online children of @parent_cs.  Must be used
 229 * with RCU read locked.
 230 */
 231#define cpuset_for_each_child(child_cs, pos_css, parent_cs)             \
 232        css_for_each_child((pos_css), &(parent_cs)->css)                \
 233                if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
 234
 235/**
 236 * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
 237 * @des_cs: loop cursor pointing to the current descendant
 238 * @pos_css: used for iteration
 239 * @root_cs: target cpuset to walk ancestor of
 240 *
 241 * Walk @des_cs through the online descendants of @root_cs.  Must be used
 242 * with RCU read locked.  The caller may modify @pos_css by calling
 243 * css_rightmost_descendant() to skip subtree.  @root_cs is included in the
 244 * iteration and the first node to be visited.
 245 */
 246#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs)        \
 247        css_for_each_descendant_pre((pos_css), &(root_cs)->css)         \
 248                if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
 249
 250/*
 251 * There are two global locks guarding cpuset structures - cpuset_mutex and
 252 * callback_lock. We also require taking task_lock() when dereferencing a
 253 * task's cpuset pointer. See "The task_lock() exception", at the end of this
 254 * comment.
 255 *
 256 * A task must hold both locks to modify cpusets.  If a task holds
 257 * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
 258 * is the only task able to also acquire callback_lock and be able to
 259 * modify cpusets.  It can perform various checks on the cpuset structure
 260 * first, knowing nothing will change.  It can also allocate memory while
 261 * just holding cpuset_mutex.  While it is performing these checks, various
 262 * callback routines can briefly acquire callback_lock to query cpusets.
 263 * Once it is ready to make the changes, it takes callback_lock, blocking
 264 * everyone else.
 265 *
 266 * Calls to the kernel memory allocator can not be made while holding
 267 * callback_lock, as that would risk double tripping on callback_lock
 268 * from one of the callbacks into the cpuset code from within
 269 * __alloc_pages().
 270 *
 271 * If a task is only holding callback_lock, then it has read-only
 272 * access to cpusets.
 273 *
 274 * Now, the task_struct fields mems_allowed and mempolicy may be changed
 275 * by other task, we use alloc_lock in the task_struct fields to protect
 276 * them.
 277 *
 278 * The cpuset_common_file_read() handlers only hold callback_lock across
 279 * small pieces of code, such as when reading out possibly multi-word
 280 * cpumasks and nodemasks.
 281 *
 282 * Accessing a task's cpuset should be done in accordance with the
 283 * guidelines for accessing subsystem state in kernel/cgroup.c
 284 */
 285
 286static DEFINE_MUTEX(cpuset_mutex);
 287static DEFINE_SPINLOCK(callback_lock);
 288
 289static struct workqueue_struct *cpuset_migrate_mm_wq;
 290
 291/*
 292 * CPU / memory hotplug is handled asynchronously.
 293 */
 294static void cpuset_hotplug_workfn(struct work_struct *work);
 295static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
 296
 297static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
 298
 299/*
 300 * This is ugly, but preserves the userspace API for existing cpuset
 301 * users. If someone tries to mount the "cpuset" filesystem, we
 302 * silently switch it to mount "cgroup" instead
 303 */
 304static struct dentry *cpuset_mount(struct file_system_type *fs_type,
 305                         int flags, const char *unused_dev_name, void *data)
 306{
 307        struct file_system_type *cgroup_fs = get_fs_type("cgroup");
 308        struct dentry *ret = ERR_PTR(-ENODEV);
 309        if (cgroup_fs) {
 310                char mountopts[] =
 311                        "cpuset,noprefix,"
 312                        "release_agent=/sbin/cpuset_release_agent";
 313                ret = cgroup_fs->mount(cgroup_fs, flags,
 314                                           unused_dev_name, mountopts);
 315                put_filesystem(cgroup_fs);
 316        }
 317        return ret;
 318}
 319
 320static struct file_system_type cpuset_fs_type = {
 321        .name = "cpuset",
 322        .mount = cpuset_mount,
 323};
 324
 325/*
 326 * Return in pmask the portion of a cpusets's cpus_allowed that
 327 * are online.  If none are online, walk up the cpuset hierarchy
 328 * until we find one that does have some online cpus.  The top
 329 * cpuset always has some cpus online.
 330 *
 331 * One way or another, we guarantee to return some non-empty subset
 332 * of cpu_online_mask.
 333 *
 334 * Call with callback_lock or cpuset_mutex held.
 335 */
 336static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
 337{
 338        while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask))
 339                cs = parent_cs(cs);
 340        cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
 341}
 342
 343/*
 344 * Return in *pmask the portion of a cpusets's mems_allowed that
 345 * are online, with memory.  If none are online with memory, walk
 346 * up the cpuset hierarchy until we find one that does have some
 347 * online mems.  The top cpuset always has some mems online.
 348 *
 349 * One way or another, we guarantee to return some non-empty subset
 350 * of node_states[N_MEMORY].
 351 *
 352 * Call with callback_lock or cpuset_mutex held.
 353 */
 354static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
 355{
 356        while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
 357                cs = parent_cs(cs);
 358        nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
 359}
 360
 361/*
 362 * update task's spread flag if cpuset's page/slab spread flag is set
 363 *
 364 * Call with callback_lock or cpuset_mutex held.
 365 */
 366static void cpuset_update_task_spread_flag(struct cpuset *cs,
 367                                        struct task_struct *tsk)
 368{
 369        if (is_spread_page(cs))
 370                task_set_spread_page(tsk);
 371        else
 372                task_clear_spread_page(tsk);
 373
 374        if (is_spread_slab(cs))
 375                task_set_spread_slab(tsk);
 376        else
 377                task_clear_spread_slab(tsk);
 378}
 379
 380/*
 381 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
 382 *
 383 * One cpuset is a subset of another if all its allowed CPUs and
 384 * Memory Nodes are a subset of the other, and its exclusive flags
 385 * are only set if the other's are set.  Call holding cpuset_mutex.
 386 */
 387
 388static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
 389{
 390        return  cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
 391                nodes_subset(p->mems_allowed, q->mems_allowed) &&
 392                is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
 393                is_mem_exclusive(p) <= is_mem_exclusive(q);
 394}
 395
 396/**
 397 * alloc_trial_cpuset - allocate a trial cpuset
 398 * @cs: the cpuset that the trial cpuset duplicates
 399 */
 400static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
 401{
 402        struct cpuset *trial;
 403
 404        trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
 405        if (!trial)
 406                return NULL;
 407
 408        if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL))
 409                goto free_cs;
 410        if (!alloc_cpumask_var(&trial->effective_cpus, GFP_KERNEL))
 411                goto free_cpus;
 412
 413        cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
 414        cpumask_copy(trial->effective_cpus, cs->effective_cpus);
 415        return trial;
 416
 417free_cpus:
 418        free_cpumask_var(trial->cpus_allowed);
 419free_cs:
 420        kfree(trial);
 421        return NULL;
 422}
 423
 424/**
 425 * free_trial_cpuset - free the trial cpuset
 426 * @trial: the trial cpuset to be freed
 427 */
 428static void free_trial_cpuset(struct cpuset *trial)
 429{
 430        free_cpumask_var(trial->effective_cpus);
 431        free_cpumask_var(trial->cpus_allowed);
 432        kfree(trial);
 433}
 434
 435/*
 436 * validate_change() - Used to validate that any proposed cpuset change
 437 *                     follows the structural rules for cpusets.
 438 *
 439 * If we replaced the flag and mask values of the current cpuset
 440 * (cur) with those values in the trial cpuset (trial), would
 441 * our various subset and exclusive rules still be valid?  Presumes
 442 * cpuset_mutex held.
 443 *
 444 * 'cur' is the address of an actual, in-use cpuset.  Operations
 445 * such as list traversal that depend on the actual address of the
 446 * cpuset in the list must use cur below, not trial.
 447 *
 448 * 'trial' is the address of bulk structure copy of cur, with
 449 * perhaps one or more of the fields cpus_allowed, mems_allowed,
 450 * or flags changed to new, trial values.
 451 *
 452 * Return 0 if valid, -errno if not.
 453 */
 454
 455static int validate_change(struct cpuset *cur, struct cpuset *trial)
 456{
 457        struct cgroup_subsys_state *css;
 458        struct cpuset *c, *par;
 459        int ret;
 460
 461        rcu_read_lock();
 462
 463        /* Each of our child cpusets must be a subset of us */
 464        ret = -EBUSY;
 465        cpuset_for_each_child(c, css, cur)
 466                if (!is_cpuset_subset(c, trial))
 467                        goto out;
 468
 469        /* Remaining checks don't apply to root cpuset */
 470        ret = 0;
 471        if (cur == &top_cpuset)
 472                goto out;
 473
 474        par = parent_cs(cur);
 475
 476        /* On legacy hiearchy, we must be a subset of our parent cpuset. */
 477        ret = -EACCES;
 478        if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
 479            !is_cpuset_subset(trial, par))
 480                goto out;
 481
 482        /*
 483         * If either I or some sibling (!= me) is exclusive, we can't
 484         * overlap
 485         */
 486        ret = -EINVAL;
 487        cpuset_for_each_child(c, css, par) {
 488                if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
 489                    c != cur &&
 490                    cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
 491                        goto out;
 492                if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
 493                    c != cur &&
 494                    nodes_intersects(trial->mems_allowed, c->mems_allowed))
 495                        goto out;
 496        }
 497
 498        /*
 499         * Cpusets with tasks - existing or newly being attached - can't
 500         * be changed to have empty cpus_allowed or mems_allowed.
 501         */
 502        ret = -ENOSPC;
 503        if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) {
 504                if (!cpumask_empty(cur->cpus_allowed) &&
 505                    cpumask_empty(trial->cpus_allowed))
 506                        goto out;
 507                if (!nodes_empty(cur->mems_allowed) &&
 508                    nodes_empty(trial->mems_allowed))
 509                        goto out;
 510        }
 511
 512        /*
 513         * We can't shrink if we won't have enough room for SCHED_DEADLINE
 514         * tasks.
 515         */
 516        ret = -EBUSY;
 517        if (is_cpu_exclusive(cur) &&
 518            !cpuset_cpumask_can_shrink(cur->cpus_allowed,
 519                                       trial->cpus_allowed))
 520                goto out;
 521
 522        ret = 0;
 523out:
 524        rcu_read_unlock();
 525        return ret;
 526}
 527
 528#ifdef CONFIG_SMP
 529/*
 530 * Helper routine for generate_sched_domains().
 531 * Do cpusets a, b have overlapping effective cpus_allowed masks?
 532 */
 533static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
 534{
 535        return cpumask_intersects(a->effective_cpus, b->effective_cpus);
 536}
 537
 538static void
 539update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
 540{
 541        if (dattr->relax_domain_level < c->relax_domain_level)
 542                dattr->relax_domain_level = c->relax_domain_level;
 543        return;
 544}
 545
 546static void update_domain_attr_tree(struct sched_domain_attr *dattr,
 547                                    struct cpuset *root_cs)
 548{
 549        struct cpuset *cp;
 550        struct cgroup_subsys_state *pos_css;
 551
 552        rcu_read_lock();
 553        cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
 554                /* skip the whole subtree if @cp doesn't have any CPU */
 555                if (cpumask_empty(cp->cpus_allowed)) {
 556                        pos_css = css_rightmost_descendant(pos_css);
 557                        continue;
 558                }
 559
 560                if (is_sched_load_balance(cp))
 561                        update_domain_attr(dattr, cp);
 562        }
 563        rcu_read_unlock();
 564}
 565
 566/*
 567 * generate_sched_domains()
 568 *
 569 * This function builds a partial partition of the systems CPUs
 570 * A 'partial partition' is a set of non-overlapping subsets whose
 571 * union is a subset of that set.
 572 * The output of this function needs to be passed to kernel/sched/core.c
 573 * partition_sched_domains() routine, which will rebuild the scheduler's
 574 * load balancing domains (sched domains) as specified by that partial
 575 * partition.
 576 *
 577 * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
 578 * for a background explanation of this.
 579 *
 580 * Does not return errors, on the theory that the callers of this
 581 * routine would rather not worry about failures to rebuild sched
 582 * domains when operating in the severe memory shortage situations
 583 * that could cause allocation failures below.
 584 *
 585 * Must be called with cpuset_mutex held.
 586 *
 587 * The three key local variables below are:
 588 *    q  - a linked-list queue of cpuset pointers, used to implement a
 589 *         top-down scan of all cpusets.  This scan loads a pointer
 590 *         to each cpuset marked is_sched_load_balance into the
 591 *         array 'csa'.  For our purposes, rebuilding the schedulers
 592 *         sched domains, we can ignore !is_sched_load_balance cpusets.
 593 *  csa  - (for CpuSet Array) Array of pointers to all the cpusets
 594 *         that need to be load balanced, for convenient iterative
 595 *         access by the subsequent code that finds the best partition,
 596 *         i.e the set of domains (subsets) of CPUs such that the
 597 *         cpus_allowed of every cpuset marked is_sched_load_balance
 598 *         is a subset of one of these domains, while there are as
 599 *         many such domains as possible, each as small as possible.
 600 * doms  - Conversion of 'csa' to an array of cpumasks, for passing to
 601 *         the kernel/sched/core.c routine partition_sched_domains() in a
 602 *         convenient format, that can be easily compared to the prior
 603 *         value to determine what partition elements (sched domains)
 604 *         were changed (added or removed.)
 605 *
 606 * Finding the best partition (set of domains):
 607 *      The triple nested loops below over i, j, k scan over the
 608 *      load balanced cpusets (using the array of cpuset pointers in
 609 *      csa[]) looking for pairs of cpusets that have overlapping
 610 *      cpus_allowed, but which don't have the same 'pn' partition
 611 *      number and gives them in the same partition number.  It keeps
 612 *      looping on the 'restart' label until it can no longer find
 613 *      any such pairs.
 614 *
 615 *      The union of the cpus_allowed masks from the set of
 616 *      all cpusets having the same 'pn' value then form the one
 617 *      element of the partition (one sched domain) to be passed to
 618 *      partition_sched_domains().
 619 */
 620static int generate_sched_domains(cpumask_var_t **domains,
 621                        struct sched_domain_attr **attributes)
 622{
 623        struct cpuset *cp;      /* scans q */
 624        struct cpuset **csa;    /* array of all cpuset ptrs */
 625        int csn;                /* how many cpuset ptrs in csa so far */
 626        int i, j, k;            /* indices for partition finding loops */
 627        cpumask_var_t *doms;    /* resulting partition; i.e. sched domains */
 628        cpumask_var_t non_isolated_cpus;  /* load balanced CPUs */
 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        struct cgroup_subsys_state *pos_css;
 633
 634        doms = NULL;
 635        dattr = NULL;
 636        csa = NULL;
 637
 638        if (!alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL))
 639                goto done;
 640        cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
 641
 642        /* Special case for the 99% of systems with one, full, sched domain */
 643        if (is_sched_load_balance(&top_cpuset)) {
 644                ndoms = 1;
 645                doms = alloc_sched_domains(ndoms);
 646                if (!doms)
 647                        goto done;
 648
 649                dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
 650                if (dattr) {
 651                        *dattr = SD_ATTR_INIT;
 652                        update_domain_attr_tree(dattr, &top_cpuset);
 653                }
 654                cpumask_and(doms[0], top_cpuset.effective_cpus,
 655                                     non_isolated_cpus);
 656
 657                goto done;
 658        }
 659
 660        csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL);
 661        if (!csa)
 662                goto done;
 663        csn = 0;
 664
 665        rcu_read_lock();
 666        cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
 667                if (cp == &top_cpuset)
 668                        continue;
 669                /*
 670                 * Continue traversing beyond @cp iff @cp has some CPUs and
 671                 * isn't load balancing.  The former is obvious.  The
 672                 * latter: All child cpusets contain a subset of the
 673                 * parent's cpus, so just skip them, and then we call
 674                 * update_domain_attr_tree() to calc relax_domain_level of
 675                 * the corresponding sched domain.
 676                 */
 677                if (!cpumask_empty(cp->cpus_allowed) &&
 678                    !(is_sched_load_balance(cp) &&
 679                      cpumask_intersects(cp->cpus_allowed, non_isolated_cpus)))
 680                        continue;
 681
 682                if (is_sched_load_balance(cp))
 683                        csa[csn++] = cp;
 684
 685                /* skip @cp's subtree */
 686                pos_css = css_rightmost_descendant(pos_css);
 687        }
 688        rcu_read_unlock();
 689
 690        for (i = 0; i < csn; i++)
 691                csa[i]->pn = i;
 692        ndoms = csn;
 693
 694restart:
 695        /* Find the best partition (set of sched domains) */
 696        for (i = 0; i < csn; i++) {
 697                struct cpuset *a = csa[i];
 698                int apn = a->pn;
 699
 700                for (j = 0; j < csn; j++) {
 701                        struct cpuset *b = csa[j];
 702                        int bpn = b->pn;
 703
 704                        if (apn != bpn && cpusets_overlap(a, b)) {
 705                                for (k = 0; k < csn; k++) {
 706                                        struct cpuset *c = csa[k];
 707
 708                                        if (c->pn == bpn)
 709                                                c->pn = apn;
 710                                }
 711                                ndoms--;        /* one less element */
 712                                goto restart;
 713                        }
 714                }
 715        }
 716
 717        /*
 718         * Now we know how many domains to create.
 719         * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
 720         */
 721        doms = alloc_sched_domains(ndoms);
 722        if (!doms)
 723                goto done;
 724
 725        /*
 726         * The rest of the code, including the scheduler, can deal with
 727         * dattr==NULL case. No need to abort if alloc fails.
 728         */
 729        dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
 730
 731        for (nslot = 0, i = 0; i < csn; i++) {
 732                struct cpuset *a = csa[i];
 733                struct cpumask *dp;
 734                int apn = a->pn;
 735
 736                if (apn < 0) {
 737                        /* Skip completed partitions */
 738                        continue;
 739                }
 740
 741                dp = doms[nslot];
 742
 743                if (nslot == ndoms) {
 744                        static int warnings = 10;
 745                        if (warnings) {
 746                                pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, 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->effective_cpus);
 761                                cpumask_and(dp, dp, non_isolated_cpus);
 762                                if (dattr)
 763                                        update_domain_attr_tree(dattr + nslot, b);
 764
 765                                /* Done with this partition */
 766                                b->pn = -1;
 767                        }
 768                }
 769                nslot++;
 770        }
 771        BUG_ON(nslot != ndoms);
 772
 773done:
 774        free_cpumask_var(non_isolated_cpus);
 775        kfree(csa);
 776
 777        /*
 778         * Fallback to the default domain if kmalloc() failed.
 779         * See comments in partition_sched_domains().
 780         */
 781        if (doms == NULL)
 782                ndoms = 1;
 783
 784        *domains    = doms;
 785        *attributes = dattr;
 786        return ndoms;
 787}
 788
 789/*
 790 * Rebuild scheduler domains.
 791 *
 792 * If the flag 'sched_load_balance' of any cpuset with non-empty
 793 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
 794 * which has that flag enabled, or if any cpuset with a non-empty
 795 * 'cpus' is removed, then call this routine to rebuild the
 796 * scheduler's dynamic sched domains.
 797 *
 798 * Call with cpuset_mutex held.  Takes get_online_cpus().
 799 */
 800static void rebuild_sched_domains_locked(void)
 801{
 802        struct sched_domain_attr *attr;
 803        cpumask_var_t *doms;
 804        int ndoms;
 805
 806        lockdep_assert_held(&cpuset_mutex);
 807        get_online_cpus();
 808
 809        /*
 810         * We have raced with CPU hotplug. Don't do anything to avoid
 811         * passing doms with offlined cpu to partition_sched_domains().
 812         * Anyways, hotplug work item will rebuild sched domains.
 813         */
 814        if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
 815                goto out;
 816
 817        /* Generate domain masks and attrs */
 818        ndoms = generate_sched_domains(&doms, &attr);
 819
 820        /* Have scheduler rebuild the domains */
 821        partition_sched_domains(ndoms, doms, attr);
 822out:
 823        put_online_cpus();
 824}
 825#else /* !CONFIG_SMP */
 826static void rebuild_sched_domains_locked(void)
 827{
 828}
 829#endif /* CONFIG_SMP */
 830
 831void rebuild_sched_domains(void)
 832{
 833        mutex_lock(&cpuset_mutex);
 834        rebuild_sched_domains_locked();
 835        mutex_unlock(&cpuset_mutex);
 836}
 837
 838/**
 839 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
 840 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
 841 *
 842 * Iterate through each task of @cs updating its cpus_allowed to the
 843 * effective cpuset's.  As this function is called with cpuset_mutex held,
 844 * cpuset membership stays stable.
 845 */
 846static void update_tasks_cpumask(struct cpuset *cs)
 847{
 848        struct css_task_iter it;
 849        struct task_struct *task;
 850
 851        css_task_iter_start(&cs->css, &it);
 852        while ((task = css_task_iter_next(&it)))
 853                set_cpus_allowed_ptr(task, cs->effective_cpus);
 854        css_task_iter_end(&it);
 855}
 856
 857/*
 858 * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
 859 * @cs: the cpuset to consider
 860 * @new_cpus: temp variable for calculating new effective_cpus
 861 *
 862 * When congifured cpumask is changed, the effective cpumasks of this cpuset
 863 * and all its descendants need to be updated.
 864 *
 865 * On legacy hierachy, effective_cpus will be the same with cpu_allowed.
 866 *
 867 * Called with cpuset_mutex held
 868 */
 869static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
 870{
 871        struct cpuset *cp;
 872        struct cgroup_subsys_state *pos_css;
 873        bool need_rebuild_sched_domains = false;
 874
 875        rcu_read_lock();
 876        cpuset_for_each_descendant_pre(cp, pos_css, cs) {
 877                struct cpuset *parent = parent_cs(cp);
 878
 879                cpumask_and(new_cpus, cp->cpus_allowed, parent->effective_cpus);
 880
 881                /*
 882                 * If it becomes empty, inherit the effective mask of the
 883                 * parent, which is guaranteed to have some CPUs.
 884                 */
 885                if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
 886                    cpumask_empty(new_cpus))
 887                        cpumask_copy(new_cpus, parent->effective_cpus);
 888
 889                /* Skip the whole subtree if the cpumask remains the same. */
 890                if (cpumask_equal(new_cpus, cp->effective_cpus)) {
 891                        pos_css = css_rightmost_descendant(pos_css);
 892                        continue;
 893                }
 894
 895                if (!css_tryget_online(&cp->css))
 896                        continue;
 897                rcu_read_unlock();
 898
 899                spin_lock_irq(&callback_lock);
 900                cpumask_copy(cp->effective_cpus, new_cpus);
 901                spin_unlock_irq(&callback_lock);
 902
 903                WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
 904                        !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
 905
 906                update_tasks_cpumask(cp);
 907
 908                /*
 909                 * If the effective cpumask of any non-empty cpuset is changed,
 910                 * we need to rebuild sched domains.
 911                 */
 912                if (!cpumask_empty(cp->cpus_allowed) &&
 913                    is_sched_load_balance(cp))
 914                        need_rebuild_sched_domains = true;
 915
 916                rcu_read_lock();
 917                css_put(&cp->css);
 918        }
 919        rcu_read_unlock();
 920
 921        if (need_rebuild_sched_domains)
 922                rebuild_sched_domains_locked();
 923}
 924
 925/**
 926 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
 927 * @cs: the cpuset to consider
 928 * @trialcs: trial cpuset
 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        int retval;
 935
 936        /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
 937        if (cs == &top_cpuset)
 938                return -EACCES;
 939
 940        /*
 941         * An empty cpus_allowed is ok only if the cpuset has no tasks.
 942         * Since cpulist_parse() fails on an empty mask, we special case
 943         * that parsing.  The validate_change() call ensures that cpusets
 944         * with tasks have cpus.
 945         */
 946        if (!*buf) {
 947                cpumask_clear(trialcs->cpus_allowed);
 948        } else {
 949                retval = cpulist_parse(buf, trialcs->cpus_allowed);
 950                if (retval < 0)
 951                        return retval;
 952
 953                if (!cpumask_subset(trialcs->cpus_allowed,
 954                                    top_cpuset.cpus_allowed))
 955                        return -EINVAL;
 956        }
 957
 958        /* Nothing to do if the cpus didn't change */
 959        if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
 960                return 0;
 961
 962        retval = validate_change(cs, trialcs);
 963        if (retval < 0)
 964                return retval;
 965
 966        spin_lock_irq(&callback_lock);
 967        cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
 968        spin_unlock_irq(&callback_lock);
 969
 970        /* use trialcs->cpus_allowed as a temp variable */
 971        update_cpumasks_hier(cs, trialcs->cpus_allowed);
 972        return 0;
 973}
 974
 975/*
 976 * Migrate memory region from one set of nodes to another.  This is
 977 * performed asynchronously as it can be called from process migration path
 978 * holding locks involved in process management.  All mm migrations are
 979 * performed in the queued order and can be waited for by flushing
 980 * cpuset_migrate_mm_wq.
 981 */
 982
 983struct cpuset_migrate_mm_work {
 984        struct work_struct      work;
 985        struct mm_struct        *mm;
 986        nodemask_t              from;
 987        nodemask_t              to;
 988};
 989
 990static void cpuset_migrate_mm_workfn(struct work_struct *work)
 991{
 992        struct cpuset_migrate_mm_work *mwork =
 993                container_of(work, struct cpuset_migrate_mm_work, work);
 994
 995        /* on a wq worker, no need to worry about %current's mems_allowed */
 996        do_migrate_pages(mwork->mm, &mwork->from, &mwork->to, MPOL_MF_MOVE_ALL);
 997        mmput(mwork->mm);
 998        kfree(mwork);
 999}
1000
1001static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
1002                                                        const nodemask_t *to)
1003{
1004        struct cpuset_migrate_mm_work *mwork;
1005
1006        mwork = kzalloc(sizeof(*mwork), GFP_KERNEL);
1007        if (mwork) {
1008                mwork->mm = mm;
1009                mwork->from = *from;
1010                mwork->to = *to;
1011                INIT_WORK(&mwork->work, cpuset_migrate_mm_workfn);
1012                queue_work(cpuset_migrate_mm_wq, &mwork->work);
1013        } else {
1014                mmput(mm);
1015        }
1016}
1017
1018static void cpuset_post_attach(void)
1019{
1020        flush_workqueue(cpuset_migrate_mm_wq);
1021}
1022
1023/*
1024 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
1025 * @tsk: the task to change
1026 * @newmems: new nodes that the task will be set
1027 *
1028 * In order to avoid seeing no nodes if the old and new nodes are disjoint,
1029 * we structure updates as setting all new allowed nodes, then clearing newly
1030 * disallowed ones.
1031 */
1032static void cpuset_change_task_nodemask(struct task_struct *tsk,
1033                                        nodemask_t *newmems)
1034{
1035        bool need_loop;
1036
1037        /*
1038         * Allow tasks that have access to memory reserves because they have
1039         * been OOM killed to get memory anywhere.
1040         */
1041        if (unlikely(test_thread_flag(TIF_MEMDIE)))
1042                return;
1043        if (current->flags & PF_EXITING) /* Let dying task have memory */
1044                return;
1045
1046        task_lock(tsk);
1047        /*
1048         * Determine if a loop is necessary if another thread is doing
1049         * read_mems_allowed_begin().  If at least one node remains unchanged and
1050         * tsk does not have a mempolicy, then an empty nodemask will not be
1051         * possible when mems_allowed is larger than a word.
1052         */
1053        need_loop = task_has_mempolicy(tsk) ||
1054                        !nodes_intersects(*newmems, tsk->mems_allowed);
1055
1056        if (need_loop) {
1057                local_irq_disable();
1058                write_seqcount_begin(&tsk->mems_allowed_seq);
1059        }
1060
1061        nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
1062        mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
1063
1064        mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
1065        tsk->mems_allowed = *newmems;
1066
1067        if (need_loop) {
1068                write_seqcount_end(&tsk->mems_allowed_seq);
1069                local_irq_enable();
1070        }
1071
1072        task_unlock(tsk);
1073}
1074
1075static void *cpuset_being_rebound;
1076
1077/**
1078 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1079 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1080 *
1081 * Iterate through each task of @cs updating its mems_allowed to the
1082 * effective cpuset's.  As this function is called with cpuset_mutex held,
1083 * cpuset membership stays stable.
1084 */
1085static void update_tasks_nodemask(struct cpuset *cs)
1086{
1087        static nodemask_t newmems;      /* protected by cpuset_mutex */
1088        struct css_task_iter it;
1089        struct task_struct *task;
1090
1091        cpuset_being_rebound = cs;              /* causes mpol_dup() rebind */
1092
1093        guarantee_online_mems(cs, &newmems);
1094
1095        /*
1096         * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
1097         * take while holding tasklist_lock.  Forks can happen - the
1098         * mpol_dup() cpuset_being_rebound check will catch such forks,
1099         * and rebind their vma mempolicies too.  Because we still hold
1100         * the global cpuset_mutex, we know that no other rebind effort
1101         * will be contending for the global variable cpuset_being_rebound.
1102         * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1103         * is idempotent.  Also migrate pages in each mm to new nodes.
1104         */
1105        css_task_iter_start(&cs->css, &it);
1106        while ((task = css_task_iter_next(&it))) {
1107                struct mm_struct *mm;
1108                bool migrate;
1109
1110                cpuset_change_task_nodemask(task, &newmems);
1111
1112                mm = get_task_mm(task);
1113                if (!mm)
1114                        continue;
1115
1116                migrate = is_memory_migrate(cs);
1117
1118                mpol_rebind_mm(mm, &cs->mems_allowed);
1119                if (migrate)
1120                        cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
1121                else
1122                        mmput(mm);
1123        }
1124        css_task_iter_end(&it);
1125
1126        /*
1127         * All the tasks' nodemasks have been updated, update
1128         * cs->old_mems_allowed.
1129         */
1130        cs->old_mems_allowed = newmems;
1131
1132        /* We're done rebinding vmas to this cpuset's new mems_allowed. */
1133        cpuset_being_rebound = NULL;
1134}
1135
1136/*
1137 * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree
1138 * @cs: the cpuset to consider
1139 * @new_mems: a temp variable for calculating new effective_mems
1140 *
1141 * When configured nodemask is changed, the effective nodemasks of this cpuset
1142 * and all its descendants need to be updated.
1143 *
1144 * On legacy hiearchy, effective_mems will be the same with mems_allowed.
1145 *
1146 * Called with cpuset_mutex held
1147 */
1148static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
1149{
1150        struct cpuset *cp;
1151        struct cgroup_subsys_state *pos_css;
1152
1153        rcu_read_lock();
1154        cpuset_for_each_descendant_pre(cp, pos_css, cs) {
1155                struct cpuset *parent = parent_cs(cp);
1156
1157                nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
1158
1159                /*
1160                 * If it becomes empty, inherit the effective mask of the
1161                 * parent, which is guaranteed to have some MEMs.
1162                 */
1163                if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
1164                    nodes_empty(*new_mems))
1165                        *new_mems = parent->effective_mems;
1166
1167                /* Skip the whole subtree if the nodemask remains the same. */
1168                if (nodes_equal(*new_mems, cp->effective_mems)) {
1169                        pos_css = css_rightmost_descendant(pos_css);
1170                        continue;
1171                }
1172
1173                if (!css_tryget_online(&cp->css))
1174                        continue;
1175                rcu_read_unlock();
1176
1177                spin_lock_irq(&callback_lock);
1178                cp->effective_mems = *new_mems;
1179                spin_unlock_irq(&callback_lock);
1180
1181                WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
1182                        !nodes_equal(cp->mems_allowed, cp->effective_mems));
1183
1184                update_tasks_nodemask(cp);
1185
1186                rcu_read_lock();
1187                css_put(&cp->css);
1188        }
1189        rcu_read_unlock();
1190}
1191
1192/*
1193 * Handle user request to change the 'mems' memory placement
1194 * of a cpuset.  Needs to validate the request, update the
1195 * cpusets mems_allowed, and for each task in the cpuset,
1196 * update mems_allowed and rebind task's mempolicy and any vma
1197 * mempolicies and if the cpuset is marked 'memory_migrate',
1198 * migrate the tasks pages to the new memory.
1199 *
1200 * Call with cpuset_mutex held. May take callback_lock during call.
1201 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1202 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
1203 * their mempolicies to the cpusets new mems_allowed.
1204 */
1205static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
1206                           const char *buf)
1207{
1208        int retval;
1209
1210        /*
1211         * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
1212         * it's read-only
1213         */
1214        if (cs == &top_cpuset) {
1215                retval = -EACCES;
1216                goto done;
1217        }
1218
1219        /*
1220         * An empty mems_allowed is ok iff there are no tasks in the cpuset.
1221         * Since nodelist_parse() fails on an empty mask, we special case
1222         * that parsing.  The validate_change() call ensures that cpusets
1223         * with tasks have memory.
1224         */
1225        if (!*buf) {
1226                nodes_clear(trialcs->mems_allowed);
1227        } else {
1228                retval = nodelist_parse(buf, trialcs->mems_allowed);
1229                if (retval < 0)
1230                        goto done;
1231
1232                if (!nodes_subset(trialcs->mems_allowed,
1233                                  top_cpuset.mems_allowed)) {
1234                        retval = -EINVAL;
1235                        goto done;
1236                }
1237        }
1238
1239        if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
1240                retval = 0;             /* Too easy - nothing to do */
1241                goto done;
1242        }
1243        retval = validate_change(cs, trialcs);
1244        if (retval < 0)
1245                goto done;
1246
1247        spin_lock_irq(&callback_lock);
1248        cs->mems_allowed = trialcs->mems_allowed;
1249        spin_unlock_irq(&callback_lock);
1250
1251        /* use trialcs->mems_allowed as a temp variable */
1252        update_nodemasks_hier(cs, &trialcs->mems_allowed);
1253done:
1254        return retval;
1255}
1256
1257int current_cpuset_is_being_rebound(void)
1258{
1259        int ret;
1260
1261        rcu_read_lock();
1262        ret = task_cs(current) == cpuset_being_rebound;
1263        rcu_read_unlock();
1264
1265        return ret;
1266}
1267
1268static int update_relax_domain_level(struct cpuset *cs, s64 val)
1269{
1270#ifdef CONFIG_SMP
1271        if (val < -1 || val >= sched_domain_level_max)
1272                return -EINVAL;
1273#endif
1274
1275        if (val != cs->relax_domain_level) {
1276                cs->relax_domain_level = val;
1277                if (!cpumask_empty(cs->cpus_allowed) &&
1278                    is_sched_load_balance(cs))
1279                        rebuild_sched_domains_locked();
1280        }
1281
1282        return 0;
1283}
1284
1285/**
1286 * update_tasks_flags - update the spread flags of tasks in the cpuset.
1287 * @cs: the cpuset in which each task's spread flags needs to be changed
1288 *
1289 * Iterate through each task of @cs updating its spread flags.  As this
1290 * function is called with cpuset_mutex held, cpuset membership stays
1291 * stable.
1292 */
1293static void update_tasks_flags(struct cpuset *cs)
1294{
1295        struct css_task_iter it;
1296        struct task_struct *task;
1297
1298        css_task_iter_start(&cs->css, &it);
1299        while ((task = css_task_iter_next(&it)))
1300                cpuset_update_task_spread_flag(cs, task);
1301        css_task_iter_end(&it);
1302}
1303
1304/*
1305 * update_flag - read a 0 or a 1 in a file and update associated flag
1306 * bit:         the bit to update (see cpuset_flagbits_t)
1307 * cs:          the cpuset to update
1308 * turning_on:  whether the flag is being set or cleared
1309 *
1310 * Call with cpuset_mutex held.
1311 */
1312
1313static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1314                       int turning_on)
1315{
1316        struct cpuset *trialcs;
1317        int balance_flag_changed;
1318        int spread_flag_changed;
1319        int err;
1320
1321        trialcs = alloc_trial_cpuset(cs);
1322        if (!trialcs)
1323                return -ENOMEM;
1324
1325        if (turning_on)
1326                set_bit(bit, &trialcs->flags);
1327        else
1328                clear_bit(bit, &trialcs->flags);
1329
1330        err = validate_change(cs, trialcs);
1331        if (err < 0)
1332                goto out;
1333
1334        balance_flag_changed = (is_sched_load_balance(cs) !=
1335                                is_sched_load_balance(trialcs));
1336
1337        spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
1338                        || (is_spread_page(cs) != is_spread_page(trialcs)));
1339
1340        spin_lock_irq(&callback_lock);
1341        cs->flags = trialcs->flags;
1342        spin_unlock_irq(&callback_lock);
1343
1344        if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1345                rebuild_sched_domains_locked();
1346
1347        if (spread_flag_changed)
1348                update_tasks_flags(cs);
1349out:
1350        free_trial_cpuset(trialcs);
1351        return err;
1352}
1353
1354/*
1355 * Frequency meter - How fast is some event occurring?
1356 *
1357 * These routines manage a digitally filtered, constant time based,
1358 * event frequency meter.  There are four routines:
1359 *   fmeter_init() - initialize a frequency meter.
1360 *   fmeter_markevent() - called each time the event happens.
1361 *   fmeter_getrate() - returns the recent rate of such events.
1362 *   fmeter_update() - internal routine used to update fmeter.
1363 *
1364 * A common data structure is passed to each of these routines,
1365 * which is used to keep track of the state required to manage the
1366 * frequency meter and its digital filter.
1367 *
1368 * The filter works on the number of events marked per unit time.
1369 * The filter is single-pole low-pass recursive (IIR).  The time unit
1370 * is 1 second.  Arithmetic is done using 32-bit integers scaled to
1371 * simulate 3 decimal digits of precision (multiplied by 1000).
1372 *
1373 * With an FM_COEF of 933, and a time base of 1 second, the filter
1374 * has a half-life of 10 seconds, meaning that if the events quit
1375 * happening, then the rate returned from the fmeter_getrate()
1376 * will be cut in half each 10 seconds, until it converges to zero.
1377 *
1378 * It is not worth doing a real infinitely recursive filter.  If more
1379 * than FM_MAXTICKS ticks have elapsed since the last filter event,
1380 * just compute FM_MAXTICKS ticks worth, by which point the level
1381 * will be stable.
1382 *
1383 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
1384 * arithmetic overflow in the fmeter_update() routine.
1385 *
1386 * Given the simple 32 bit integer arithmetic used, this meter works
1387 * best for reporting rates between one per millisecond (msec) and
1388 * one per 32 (approx) seconds.  At constant rates faster than one
1389 * per msec it maxes out at values just under 1,000,000.  At constant
1390 * rates between one per msec, and one per second it will stabilize
1391 * to a value N*1000, where N is the rate of events per second.
1392 * At constant rates between one per second and one per 32 seconds,
1393 * it will be choppy, moving up on the seconds that have an event,
1394 * and then decaying until the next event.  At rates slower than
1395 * about one in 32 seconds, it decays all the way back to zero between
1396 * each event.
1397 */
1398
1399#define FM_COEF 933             /* coefficient for half-life of 10 secs */
1400#define FM_MAXTICKS ((u32)99)   /* useless computing more ticks than this */
1401#define FM_MAXCNT 1000000       /* limit cnt to avoid overflow */
1402#define FM_SCALE 1000           /* faux fixed point scale */
1403
1404/* Initialize a frequency meter */
1405static void fmeter_init(struct fmeter *fmp)
1406{
1407        fmp->cnt = 0;
1408        fmp->val = 0;
1409        fmp->time = 0;
1410        spin_lock_init(&fmp->lock);
1411}
1412
1413/* Internal meter update - process cnt events and update value */
1414static void fmeter_update(struct fmeter *fmp)
1415{
1416        time64_t now;
1417        u32 ticks;
1418
1419        now = ktime_get_seconds();
1420        ticks = now - fmp->time;
1421
1422        if (ticks == 0)
1423                return;
1424
1425        ticks = min(FM_MAXTICKS, ticks);
1426        while (ticks-- > 0)
1427                fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
1428        fmp->time = now;
1429
1430        fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
1431        fmp->cnt = 0;
1432}
1433
1434/* Process any previous ticks, then bump cnt by one (times scale). */
1435static void fmeter_markevent(struct fmeter *fmp)
1436{
1437        spin_lock(&fmp->lock);
1438        fmeter_update(fmp);
1439        fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
1440        spin_unlock(&fmp->lock);
1441}
1442
1443/* Process any previous ticks, then return current value. */
1444static int fmeter_getrate(struct fmeter *fmp)
1445{
1446        int val;
1447
1448        spin_lock(&fmp->lock);
1449        fmeter_update(fmp);
1450        val = fmp->val;
1451        spin_unlock(&fmp->lock);
1452        return val;
1453}
1454
1455static struct cpuset *cpuset_attach_old_cs;
1456
1457/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
1458static int cpuset_can_attach(struct cgroup_taskset *tset)
1459{
1460        struct cgroup_subsys_state *css;
1461        struct cpuset *cs;
1462        struct task_struct *task;
1463        int ret;
1464
1465        /* used later by cpuset_attach() */
1466        cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
1467        cs = css_cs(css);
1468
1469        mutex_lock(&cpuset_mutex);
1470
1471        /* allow moving tasks into an empty cpuset if on default hierarchy */
1472        ret = -ENOSPC;
1473        if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
1474            (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
1475                goto out_unlock;
1476
1477        cgroup_taskset_for_each(task, css, tset) {
1478                ret = task_can_attach(task, cs->cpus_allowed);
1479                if (ret)
1480                        goto out_unlock;
1481                ret = security_task_setscheduler(task);
1482                if (ret)
1483                        goto out_unlock;
1484        }
1485
1486        /*
1487         * Mark attach is in progress.  This makes validate_change() fail
1488         * changes which zero cpus/mems_allowed.
1489         */
1490        cs->attach_in_progress++;
1491        ret = 0;
1492out_unlock:
1493        mutex_unlock(&cpuset_mutex);
1494        return ret;
1495}
1496
1497static void cpuset_cancel_attach(struct cgroup_taskset *tset)
1498{
1499        struct cgroup_subsys_state *css;
1500        struct cpuset *cs;
1501
1502        cgroup_taskset_first(tset, &css);
1503        cs = css_cs(css);
1504
1505        mutex_lock(&cpuset_mutex);
1506        css_cs(css)->attach_in_progress--;
1507        mutex_unlock(&cpuset_mutex);
1508}
1509
1510/*
1511 * Protected by cpuset_mutex.  cpus_attach is used only by cpuset_attach()
1512 * but we can't allocate it dynamically there.  Define it global and
1513 * allocate from cpuset_init().
1514 */
1515static cpumask_var_t cpus_attach;
1516
1517static void cpuset_attach(struct cgroup_taskset *tset)
1518{
1519        /* static buf protected by cpuset_mutex */
1520        static nodemask_t cpuset_attach_nodemask_to;
1521        struct task_struct *task;
1522        struct task_struct *leader;
1523        struct cgroup_subsys_state *css;
1524        struct cpuset *cs;
1525        struct cpuset *oldcs = cpuset_attach_old_cs;
1526
1527        cgroup_taskset_first(tset, &css);
1528        cs = css_cs(css);
1529
1530        mutex_lock(&cpuset_mutex);
1531
1532        /* prepare for attach */
1533        if (cs == &top_cpuset)
1534                cpumask_copy(cpus_attach, cpu_possible_mask);
1535        else
1536                guarantee_online_cpus(cs, cpus_attach);
1537
1538        guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
1539
1540        cgroup_taskset_for_each(task, css, tset) {
1541                /*
1542                 * can_attach beforehand should guarantee that this doesn't
1543                 * fail.  TODO: have a better way to handle failure here
1544                 */
1545                WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
1546
1547                cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
1548                cpuset_update_task_spread_flag(cs, task);
1549        }
1550
1551        /*
1552         * Change mm for all threadgroup leaders. This is expensive and may
1553         * sleep and should be moved outside migration path proper.
1554         */
1555        cpuset_attach_nodemask_to = cs->effective_mems;
1556        cgroup_taskset_for_each_leader(leader, css, tset) {
1557                struct mm_struct *mm = get_task_mm(leader);
1558
1559                if (mm) {
1560                        mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
1561
1562                        /*
1563                         * old_mems_allowed is the same with mems_allowed
1564                         * here, except if this task is being moved
1565                         * automatically due to hotplug.  In that case
1566                         * @mems_allowed has been updated and is empty, so
1567                         * @old_mems_allowed is the right nodesets that we
1568                         * migrate mm from.
1569                         */
1570                        if (is_memory_migrate(cs))
1571                                cpuset_migrate_mm(mm, &oldcs->old_mems_allowed,
1572                                                  &cpuset_attach_nodemask_to);
1573                        else
1574                                mmput(mm);
1575                }
1576        }
1577
1578        cs->old_mems_allowed = cpuset_attach_nodemask_to;
1579
1580        cs->attach_in_progress--;
1581        if (!cs->attach_in_progress)
1582                wake_up(&cpuset_attach_wq);
1583
1584        mutex_unlock(&cpuset_mutex);
1585}
1586
1587/* The various types of files and directories in a cpuset file system */
1588
1589typedef enum {
1590        FILE_MEMORY_MIGRATE,
1591        FILE_CPULIST,
1592        FILE_MEMLIST,
1593        FILE_EFFECTIVE_CPULIST,
1594        FILE_EFFECTIVE_MEMLIST,
1595        FILE_CPU_EXCLUSIVE,
1596        FILE_MEM_EXCLUSIVE,
1597        FILE_MEM_HARDWALL,
1598        FILE_SCHED_LOAD_BALANCE,
1599        FILE_SCHED_RELAX_DOMAIN_LEVEL,
1600        FILE_MEMORY_PRESSURE_ENABLED,
1601        FILE_MEMORY_PRESSURE,
1602        FILE_SPREAD_PAGE,
1603        FILE_SPREAD_SLAB,
1604} cpuset_filetype_t;
1605
1606static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
1607                            u64 val)
1608{
1609        struct cpuset *cs = css_cs(css);
1610        cpuset_filetype_t type = cft->private;
1611        int retval = 0;
1612
1613        mutex_lock(&cpuset_mutex);
1614        if (!is_cpuset_online(cs)) {
1615                retval = -ENODEV;
1616                goto out_unlock;
1617        }
1618
1619        switch (type) {
1620        case FILE_CPU_EXCLUSIVE:
1621                retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
1622                break;
1623        case FILE_MEM_EXCLUSIVE:
1624                retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
1625                break;
1626        case FILE_MEM_HARDWALL:
1627                retval = update_flag(CS_MEM_HARDWALL, cs, val);
1628                break;
1629        case FILE_SCHED_LOAD_BALANCE:
1630                retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1631                break;
1632        case FILE_MEMORY_MIGRATE:
1633                retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1634                break;
1635        case FILE_MEMORY_PRESSURE_ENABLED:
1636                cpuset_memory_pressure_enabled = !!val;
1637                break;
1638        case FILE_SPREAD_PAGE:
1639                retval = update_flag(CS_SPREAD_PAGE, cs, val);
1640                break;
1641        case FILE_SPREAD_SLAB:
1642                retval = update_flag(CS_SPREAD_SLAB, cs, val);
1643                break;
1644        default:
1645                retval = -EINVAL;
1646                break;
1647        }
1648out_unlock:
1649        mutex_unlock(&cpuset_mutex);
1650        return retval;
1651}
1652
1653static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
1654                            s64 val)
1655{
1656        struct cpuset *cs = css_cs(css);
1657        cpuset_filetype_t type = cft->private;
1658        int retval = -ENODEV;
1659
1660        mutex_lock(&cpuset_mutex);
1661        if (!is_cpuset_online(cs))
1662                goto out_unlock;
1663
1664        switch (type) {
1665        case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1666                retval = update_relax_domain_level(cs, val);
1667                break;
1668        default:
1669                retval = -EINVAL;
1670                break;
1671        }
1672out_unlock:
1673        mutex_unlock(&cpuset_mutex);
1674        return retval;
1675}
1676
1677/*
1678 * Common handling for a write to a "cpus" or "mems" file.
1679 */
1680static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
1681                                    char *buf, size_t nbytes, loff_t off)
1682{
1683        struct cpuset *cs = css_cs(of_css(of));
1684        struct cpuset *trialcs;
1685        int retval = -ENODEV;
1686
1687        buf = strstrip(buf);
1688
1689        /*
1690         * CPU or memory hotunplug may leave @cs w/o any execution
1691         * resources, in which case the hotplug code asynchronously updates
1692         * configuration and transfers all tasks to the nearest ancestor
1693         * which can execute.
1694         *
1695         * As writes to "cpus" or "mems" may restore @cs's execution
1696         * resources, wait for the previously scheduled operations before
1697         * proceeding, so that we don't end up keep removing tasks added
1698         * after execution capability is restored.
1699         *
1700         * cpuset_hotplug_work calls back into cgroup core via
1701         * cgroup_transfer_tasks() and waiting for it from a cgroupfs
1702         * operation like this one can lead to a deadlock through kernfs
1703         * active_ref protection.  Let's break the protection.  Losing the
1704         * protection is okay as we check whether @cs is online after
1705         * grabbing cpuset_mutex anyway.  This only happens on the legacy
1706         * hierarchies.
1707         */
1708        css_get(&cs->css);
1709        kernfs_break_active_protection(of->kn);
1710        flush_work(&cpuset_hotplug_work);
1711
1712        mutex_lock(&cpuset_mutex);
1713        if (!is_cpuset_online(cs))
1714                goto out_unlock;
1715
1716        trialcs = alloc_trial_cpuset(cs);
1717        if (!trialcs) {
1718                retval = -ENOMEM;
1719                goto out_unlock;
1720        }
1721
1722        switch (of_cft(of)->private) {
1723        case FILE_CPULIST:
1724                retval = update_cpumask(cs, trialcs, buf);
1725                break;
1726        case FILE_MEMLIST:
1727                retval = update_nodemask(cs, trialcs, buf);
1728                break;
1729        default:
1730                retval = -EINVAL;
1731                break;
1732        }
1733
1734        free_trial_cpuset(trialcs);
1735out_unlock:
1736        mutex_unlock(&cpuset_mutex);
1737        kernfs_unbreak_active_protection(of->kn);
1738        css_put(&cs->css);
1739        flush_workqueue(cpuset_migrate_mm_wq);
1740        return retval ?: nbytes;
1741}
1742
1743/*
1744 * These ascii lists should be read in a single call, by using a user
1745 * buffer large enough to hold the entire map.  If read in smaller
1746 * chunks, there is no guarantee of atomicity.  Since the display format
1747 * used, list of ranges of sequential numbers, is variable length,
1748 * and since these maps can change value dynamically, one could read
1749 * gibberish by doing partial reads while a list was changing.
1750 */
1751static int cpuset_common_seq_show(struct seq_file *sf, void *v)
1752{
1753        struct cpuset *cs = css_cs(seq_css(sf));
1754        cpuset_filetype_t type = seq_cft(sf)->private;
1755        int ret = 0;
1756
1757        spin_lock_irq(&callback_lock);
1758
1759        switch (type) {
1760        case FILE_CPULIST:
1761                seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_allowed));
1762                break;
1763        case FILE_MEMLIST:
1764                seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed));
1765                break;
1766        case FILE_EFFECTIVE_CPULIST:
1767                seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus));
1768                break;
1769        case FILE_EFFECTIVE_MEMLIST:
1770                seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems));
1771                break;
1772        default:
1773                ret = -EINVAL;
1774        }
1775
1776        spin_unlock_irq(&callback_lock);
1777        return ret;
1778}
1779
1780static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
1781{
1782        struct cpuset *cs = css_cs(css);
1783        cpuset_filetype_t type = cft->private;
1784        switch (type) {
1785        case FILE_CPU_EXCLUSIVE:
1786                return is_cpu_exclusive(cs);
1787        case FILE_MEM_EXCLUSIVE:
1788                return is_mem_exclusive(cs);
1789        case FILE_MEM_HARDWALL:
1790                return is_mem_hardwall(cs);
1791        case FILE_SCHED_LOAD_BALANCE:
1792                return is_sched_load_balance(cs);
1793        case FILE_MEMORY_MIGRATE:
1794                return is_memory_migrate(cs);
1795        case FILE_MEMORY_PRESSURE_ENABLED:
1796                return cpuset_memory_pressure_enabled;
1797        case FILE_MEMORY_PRESSURE:
1798                return fmeter_getrate(&cs->fmeter);
1799        case FILE_SPREAD_PAGE:
1800                return is_spread_page(cs);
1801        case FILE_SPREAD_SLAB:
1802                return is_spread_slab(cs);
1803        default:
1804                BUG();
1805        }
1806
1807        /* Unreachable but makes gcc happy */
1808        return 0;
1809}
1810
1811static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
1812{
1813        struct cpuset *cs = css_cs(css);
1814        cpuset_filetype_t type = cft->private;
1815        switch (type) {
1816        case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1817                return cs->relax_domain_level;
1818        default:
1819                BUG();
1820        }
1821
1822        /* Unrechable but makes gcc happy */
1823        return 0;
1824}
1825
1826
1827/*
1828 * for the common functions, 'private' gives the type of file
1829 */
1830
1831static struct cftype files[] = {
1832        {
1833                .name = "cpus",
1834                .seq_show = cpuset_common_seq_show,
1835                .write = cpuset_write_resmask,
1836                .max_write_len = (100U + 6 * NR_CPUS),
1837                .private = FILE_CPULIST,
1838        },
1839
1840        {
1841                .name = "mems",
1842                .seq_show = cpuset_common_seq_show,
1843                .write = cpuset_write_resmask,
1844                .max_write_len = (100U + 6 * MAX_NUMNODES),
1845                .private = FILE_MEMLIST,
1846        },
1847
1848        {
1849                .name = "effective_cpus",
1850                .seq_show = cpuset_common_seq_show,
1851                .private = FILE_EFFECTIVE_CPULIST,
1852        },
1853
1854        {
1855                .name = "effective_mems",
1856                .seq_show = cpuset_common_seq_show,
1857                .private = FILE_EFFECTIVE_MEMLIST,
1858        },
1859
1860        {
1861                .name = "cpu_exclusive",
1862                .read_u64 = cpuset_read_u64,
1863                .write_u64 = cpuset_write_u64,
1864                .private = FILE_CPU_EXCLUSIVE,
1865        },
1866
1867        {
1868                .name = "mem_exclusive",
1869                .read_u64 = cpuset_read_u64,
1870                .write_u64 = cpuset_write_u64,
1871                .private = FILE_MEM_EXCLUSIVE,
1872        },
1873
1874        {
1875                .name = "mem_hardwall",
1876                .read_u64 = cpuset_read_u64,
1877                .write_u64 = cpuset_write_u64,
1878                .private = FILE_MEM_HARDWALL,
1879        },
1880
1881        {
1882                .name = "sched_load_balance",
1883                .read_u64 = cpuset_read_u64,
1884                .write_u64 = cpuset_write_u64,
1885                .private = FILE_SCHED_LOAD_BALANCE,
1886        },
1887
1888        {
1889                .name = "sched_relax_domain_level",
1890                .read_s64 = cpuset_read_s64,
1891                .write_s64 = cpuset_write_s64,
1892                .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
1893        },
1894
1895        {
1896                .name = "memory_migrate",
1897                .read_u64 = cpuset_read_u64,
1898                .write_u64 = cpuset_write_u64,
1899                .private = FILE_MEMORY_MIGRATE,
1900        },
1901
1902        {
1903                .name = "memory_pressure",
1904                .read_u64 = cpuset_read_u64,
1905        },
1906
1907        {
1908                .name = "memory_spread_page",
1909                .read_u64 = cpuset_read_u64,
1910                .write_u64 = cpuset_write_u64,
1911                .private = FILE_SPREAD_PAGE,
1912        },
1913
1914        {
1915                .name = "memory_spread_slab",
1916                .read_u64 = cpuset_read_u64,
1917                .write_u64 = cpuset_write_u64,
1918                .private = FILE_SPREAD_SLAB,
1919        },
1920
1921        {
1922                .name = "memory_pressure_enabled",
1923                .flags = CFTYPE_ONLY_ON_ROOT,
1924                .read_u64 = cpuset_read_u64,
1925                .write_u64 = cpuset_write_u64,
1926                .private = FILE_MEMORY_PRESSURE_ENABLED,
1927        },
1928
1929        { }     /* terminate */
1930};
1931
1932/*
1933 *      cpuset_css_alloc - allocate a cpuset css
1934 *      cgrp:   control group that the new cpuset will be part of
1935 */
1936
1937static struct cgroup_subsys_state *
1938cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
1939{
1940        struct cpuset *cs;
1941
1942        if (!parent_css)
1943                return &top_cpuset.css;
1944
1945        cs = kzalloc(sizeof(*cs), GFP_KERNEL);
1946        if (!cs)
1947                return ERR_PTR(-ENOMEM);
1948        if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL))
1949                goto free_cs;
1950        if (!alloc_cpumask_var(&cs->effective_cpus, GFP_KERNEL))
1951                goto free_cpus;
1952
1953        set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1954        cpumask_clear(cs->cpus_allowed);
1955        nodes_clear(cs->mems_allowed);
1956        cpumask_clear(cs->effective_cpus);
1957        nodes_clear(cs->effective_mems);
1958        fmeter_init(&cs->fmeter);
1959        cs->relax_domain_level = -1;
1960
1961        return &cs->css;
1962
1963free_cpus:
1964        free_cpumask_var(cs->cpus_allowed);
1965free_cs:
1966        kfree(cs);
1967        return ERR_PTR(-ENOMEM);
1968}
1969
1970static int cpuset_css_online(struct cgroup_subsys_state *css)
1971{
1972        struct cpuset *cs = css_cs(css);
1973        struct cpuset *parent = parent_cs(cs);
1974        struct cpuset *tmp_cs;
1975        struct cgroup_subsys_state *pos_css;
1976
1977        if (!parent)
1978                return 0;
1979
1980        mutex_lock(&cpuset_mutex);
1981
1982        set_bit(CS_ONLINE, &cs->flags);
1983        if (is_spread_page(parent))
1984                set_bit(CS_SPREAD_PAGE, &cs->flags);
1985        if (is_spread_slab(parent))
1986                set_bit(CS_SPREAD_SLAB, &cs->flags);
1987
1988        cpuset_inc();
1989
1990        spin_lock_irq(&callback_lock);
1991        if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
1992                cpumask_copy(cs->effective_cpus, parent->effective_cpus);
1993                cs->effective_mems = parent->effective_mems;
1994        }
1995        spin_unlock_irq(&callback_lock);
1996
1997        if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
1998                goto out_unlock;
1999
2000        /*
2001         * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
2002         * set.  This flag handling is implemented in cgroup core for
2003         * histrical reasons - the flag may be specified during mount.
2004         *
2005         * Currently, if any sibling cpusets have exclusive cpus or mem, we
2006         * refuse to clone the configuration - thereby refusing the task to
2007         * be entered, and as a result refusing the sys_unshare() or
2008         * clone() which initiated it.  If this becomes a problem for some
2009         * users who wish to allow that scenario, then this could be
2010         * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
2011         * (and likewise for mems) to the new cgroup.
2012         */
2013        rcu_read_lock();
2014        cpuset_for_each_child(tmp_cs, pos_css, parent) {
2015                if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
2016                        rcu_read_unlock();
2017                        goto out_unlock;
2018                }
2019        }
2020        rcu_read_unlock();
2021
2022        spin_lock_irq(&callback_lock);
2023        cs->mems_allowed = parent->mems_allowed;
2024        cs->effective_mems = parent->mems_allowed;
2025        cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
2026        cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
2027        spin_unlock_irq(&callback_lock);
2028out_unlock:
2029        mutex_unlock(&cpuset_mutex);
2030        return 0;
2031}
2032
2033/*
2034 * If the cpuset being removed has its flag 'sched_load_balance'
2035 * enabled, then simulate turning sched_load_balance off, which
2036 * will call rebuild_sched_domains_locked().
2037 */
2038
2039static void cpuset_css_offline(struct cgroup_subsys_state *css)
2040{
2041        struct cpuset *cs = css_cs(css);
2042
2043        mutex_lock(&cpuset_mutex);
2044
2045        if (is_sched_load_balance(cs))
2046                update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
2047
2048        cpuset_dec();
2049        clear_bit(CS_ONLINE, &cs->flags);
2050
2051        mutex_unlock(&cpuset_mutex);
2052}
2053
2054static void cpuset_css_free(struct cgroup_subsys_state *css)
2055{
2056        struct cpuset *cs = css_cs(css);
2057
2058        free_cpumask_var(cs->effective_cpus);
2059        free_cpumask_var(cs->cpus_allowed);
2060        kfree(cs);
2061}
2062
2063static void cpuset_bind(struct cgroup_subsys_state *root_css)
2064{
2065        mutex_lock(&cpuset_mutex);
2066        spin_lock_irq(&callback_lock);
2067
2068        if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
2069                cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
2070                top_cpuset.mems_allowed = node_possible_map;
2071        } else {
2072                cpumask_copy(top_cpuset.cpus_allowed,
2073                             top_cpuset.effective_cpus);
2074                top_cpuset.mems_allowed = top_cpuset.effective_mems;
2075        }
2076
2077        spin_unlock_irq(&callback_lock);
2078        mutex_unlock(&cpuset_mutex);
2079}
2080
2081/*
2082 * Make sure the new task conform to the current state of its parent,
2083 * which could have been changed by cpuset just after it inherits the
2084 * state from the parent and before it sits on the cgroup's task list.
2085 */
2086void cpuset_fork(struct task_struct *task)
2087{
2088        if (task_css_is_root(task, cpuset_cgrp_id))
2089                return;
2090
2091        set_cpus_allowed_ptr(task, &current->cpus_allowed);
2092        task->mems_allowed = current->mems_allowed;
2093}
2094
2095struct cgroup_subsys cpuset_cgrp_subsys = {
2096        .css_alloc      = cpuset_css_alloc,
2097        .css_online     = cpuset_css_online,
2098        .css_offline    = cpuset_css_offline,
2099        .css_free       = cpuset_css_free,
2100        .can_attach     = cpuset_can_attach,
2101        .cancel_attach  = cpuset_cancel_attach,
2102        .attach         = cpuset_attach,
2103        .post_attach    = cpuset_post_attach,
2104        .bind           = cpuset_bind,
2105        .fork           = cpuset_fork,
2106        .legacy_cftypes = files,
2107        .early_init     = true,
2108};
2109
2110/**
2111 * cpuset_init - initialize cpusets at system boot
2112 *
2113 * Description: Initialize top_cpuset and the cpuset internal file system,
2114 **/
2115
2116int __init cpuset_init(void)
2117{
2118        int err = 0;
2119
2120        if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
2121                BUG();
2122        if (!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL))
2123                BUG();
2124
2125        cpumask_setall(top_cpuset.cpus_allowed);
2126        nodes_setall(top_cpuset.mems_allowed);
2127        cpumask_setall(top_cpuset.effective_cpus);
2128        nodes_setall(top_cpuset.effective_mems);
2129
2130        fmeter_init(&top_cpuset.fmeter);
2131        set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
2132        top_cpuset.relax_domain_level = -1;
2133
2134        err = register_filesystem(&cpuset_fs_type);
2135        if (err < 0)
2136                return err;
2137
2138        if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
2139                BUG();
2140
2141        return 0;
2142}
2143
2144/*
2145 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
2146 * or memory nodes, we need to walk over the cpuset hierarchy,
2147 * removing that CPU or node from all cpusets.  If this removes the
2148 * last CPU or node from a cpuset, then move the tasks in the empty
2149 * cpuset to its next-highest non-empty parent.
2150 */
2151static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
2152{
2153        struct cpuset *parent;
2154
2155        /*
2156         * Find its next-highest non-empty parent, (top cpuset
2157         * has online cpus, so can't be empty).
2158         */
2159        parent = parent_cs(cs);
2160        while (cpumask_empty(parent->cpus_allowed) ||
2161                        nodes_empty(parent->mems_allowed))
2162                parent = parent_cs(parent);
2163
2164        if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
2165                pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
2166                pr_cont_cgroup_name(cs->css.cgroup);
2167                pr_cont("\n");
2168        }
2169}
2170
2171static void
2172hotplug_update_tasks_legacy(struct cpuset *cs,
2173                            struct cpumask *new_cpus, nodemask_t *new_mems,
2174                            bool cpus_updated, bool mems_updated)
2175{
2176        bool is_empty;
2177
2178        spin_lock_irq(&callback_lock);
2179        cpumask_copy(cs->cpus_allowed, new_cpus);
2180        cpumask_copy(cs->effective_cpus, new_cpus);
2181        cs->mems_allowed = *new_mems;
2182        cs->effective_mems = *new_mems;
2183        spin_unlock_irq(&callback_lock);
2184
2185        /*
2186         * Don't call update_tasks_cpumask() if the cpuset becomes empty,
2187         * as the tasks will be migratecd to an ancestor.
2188         */
2189        if (cpus_updated && !cpumask_empty(cs->cpus_allowed))
2190                update_tasks_cpumask(cs);
2191        if (mems_updated && !nodes_empty(cs->mems_allowed))
2192                update_tasks_nodemask(cs);
2193
2194        is_empty = cpumask_empty(cs->cpus_allowed) ||
2195                   nodes_empty(cs->mems_allowed);
2196
2197        mutex_unlock(&cpuset_mutex);
2198
2199        /*
2200         * Move tasks to the nearest ancestor with execution resources,
2201         * This is full cgroup operation which will also call back into
2202         * cpuset. Should be done outside any lock.
2203         */
2204        if (is_empty)
2205                remove_tasks_in_empty_cpuset(cs);
2206
2207        mutex_lock(&cpuset_mutex);
2208}
2209
2210static void
2211hotplug_update_tasks(struct cpuset *cs,
2212                     struct cpumask *new_cpus, nodemask_t *new_mems,
2213                     bool cpus_updated, bool mems_updated)
2214{
2215        if (cpumask_empty(new_cpus))
2216                cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
2217        if (nodes_empty(*new_mems))
2218                *new_mems = parent_cs(cs)->effective_mems;
2219
2220        spin_lock_irq(&callback_lock);
2221        cpumask_copy(cs->effective_cpus, new_cpus);
2222        cs->effective_mems = *new_mems;
2223        spin_unlock_irq(&callback_lock);
2224
2225        if (cpus_updated)
2226                update_tasks_cpumask(cs);
2227        if (mems_updated)
2228                update_tasks_nodemask(cs);
2229}
2230
2231/**
2232 * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
2233 * @cs: cpuset in interest
2234 *
2235 * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
2236 * offline, update @cs accordingly.  If @cs ends up with no CPU or memory,
2237 * all its tasks are moved to the nearest ancestor with both resources.
2238 */
2239static void cpuset_hotplug_update_tasks(struct cpuset *cs)
2240{
2241        static cpumask_t new_cpus;
2242        static nodemask_t new_mems;
2243        bool cpus_updated;
2244        bool mems_updated;
2245retry:
2246        wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
2247
2248        mutex_lock(&cpuset_mutex);
2249
2250        /*
2251         * We have raced with task attaching. We wait until attaching
2252         * is finished, so we won't attach a task to an empty cpuset.
2253         */
2254        if (cs->attach_in_progress) {
2255                mutex_unlock(&cpuset_mutex);
2256                goto retry;
2257        }
2258
2259        cpumask_and(&new_cpus, cs->cpus_allowed, parent_cs(cs)->effective_cpus);
2260        nodes_and(new_mems, cs->mems_allowed, parent_cs(cs)->effective_mems);
2261
2262        cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
2263        mems_updated = !nodes_equal(new_mems, cs->effective_mems);
2264
2265        if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys))
2266                hotplug_update_tasks(cs, &new_cpus, &new_mems,
2267                                     cpus_updated, mems_updated);
2268        else
2269                hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems,
2270                                            cpus_updated, mems_updated);
2271
2272        mutex_unlock(&cpuset_mutex);
2273}
2274
2275/**
2276 * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
2277 *
2278 * This function is called after either CPU or memory configuration has
2279 * changed and updates cpuset accordingly.  The top_cpuset is always
2280 * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
2281 * order to make cpusets transparent (of no affect) on systems that are
2282 * actively using CPU hotplug but making no active use of cpusets.
2283 *
2284 * Non-root cpusets are only affected by offlining.  If any CPUs or memory
2285 * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
2286 * all descendants.
2287 *
2288 * Note that CPU offlining during suspend is ignored.  We don't modify
2289 * cpusets across suspend/resume cycles at all.
2290 */
2291static void cpuset_hotplug_workfn(struct work_struct *work)
2292{
2293        static cpumask_t new_cpus;
2294        static nodemask_t new_mems;
2295        bool cpus_updated, mems_updated;
2296        bool on_dfl = cgroup_subsys_on_dfl(cpuset_cgrp_subsys);
2297
2298        mutex_lock(&cpuset_mutex);
2299
2300        /* fetch the available cpus/mems and find out which changed how */
2301        cpumask_copy(&new_cpus, cpu_active_mask);
2302        new_mems = node_states[N_MEMORY];
2303
2304        cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
2305        mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
2306
2307        /* synchronize cpus_allowed to cpu_active_mask */
2308        if (cpus_updated) {
2309                spin_lock_irq(&callback_lock);
2310                if (!on_dfl)
2311                        cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
2312                cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
2313                spin_unlock_irq(&callback_lock);
2314                /* we don't mess with cpumasks of tasks in top_cpuset */
2315        }
2316
2317        /* synchronize mems_allowed to N_MEMORY */
2318        if (mems_updated) {
2319                spin_lock_irq(&callback_lock);
2320                if (!on_dfl)
2321                        top_cpuset.mems_allowed = new_mems;
2322                top_cpuset.effective_mems = new_mems;
2323                spin_unlock_irq(&callback_lock);
2324                update_tasks_nodemask(&top_cpuset);
2325        }
2326
2327        mutex_unlock(&cpuset_mutex);
2328
2329        /* if cpus or mems changed, we need to propagate to descendants */
2330        if (cpus_updated || mems_updated) {
2331                struct cpuset *cs;
2332                struct cgroup_subsys_state *pos_css;
2333
2334                rcu_read_lock();
2335                cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
2336                        if (cs == &top_cpuset || !css_tryget_online(&cs->css))
2337                                continue;
2338                        rcu_read_unlock();
2339
2340                        cpuset_hotplug_update_tasks(cs);
2341
2342                        rcu_read_lock();
2343                        css_put(&cs->css);
2344                }
2345                rcu_read_unlock();
2346        }
2347
2348        /* rebuild sched domains if cpus_allowed has changed */
2349        if (cpus_updated)
2350                rebuild_sched_domains();
2351}
2352
2353void cpuset_update_active_cpus(bool cpu_online)
2354{
2355        /*
2356         * We're inside cpu hotplug critical region which usually nests
2357         * inside cgroup synchronization.  Bounce actual hotplug processing
2358         * to a work item to avoid reverse locking order.
2359         *
2360         * We still need to do partition_sched_domains() synchronously;
2361         * otherwise, the scheduler will get confused and put tasks to the
2362         * dead CPU.  Fall back to the default single domain.
2363         * cpuset_hotplug_workfn() will rebuild it as necessary.
2364         */
2365        partition_sched_domains(1, NULL, NULL);
2366        schedule_work(&cpuset_hotplug_work);
2367}
2368
2369/*
2370 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
2371 * Call this routine anytime after node_states[N_MEMORY] changes.
2372 * See cpuset_update_active_cpus() for CPU hotplug handling.
2373 */
2374static int cpuset_track_online_nodes(struct notifier_block *self,
2375                                unsigned long action, void *arg)
2376{
2377        schedule_work(&cpuset_hotplug_work);
2378        return NOTIFY_OK;
2379}
2380
2381static struct notifier_block cpuset_track_online_nodes_nb = {
2382        .notifier_call = cpuset_track_online_nodes,
2383        .priority = 10,         /* ??! */
2384};
2385
2386/**
2387 * cpuset_init_smp - initialize cpus_allowed
2388 *
2389 * Description: Finish top cpuset after cpu, node maps are initialized
2390 */
2391void __init cpuset_init_smp(void)
2392{
2393        cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2394        top_cpuset.mems_allowed = node_states[N_MEMORY];
2395        top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
2396
2397        cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
2398        top_cpuset.effective_mems = node_states[N_MEMORY];
2399
2400        register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
2401
2402        cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0);
2403        BUG_ON(!cpuset_migrate_mm_wq);
2404}
2405
2406/**
2407 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
2408 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2409 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
2410 *
2411 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
2412 * attached to the specified @tsk.  Guaranteed to return some non-empty
2413 * subset of cpu_online_mask, even if this means going outside the
2414 * tasks cpuset.
2415 **/
2416
2417void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
2418{
2419        unsigned long flags;
2420
2421        spin_lock_irqsave(&callback_lock, flags);
2422        rcu_read_lock();
2423        guarantee_online_cpus(task_cs(tsk), pmask);
2424        rcu_read_unlock();
2425        spin_unlock_irqrestore(&callback_lock, flags);
2426}
2427
2428void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
2429{
2430        rcu_read_lock();
2431        do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
2432        rcu_read_unlock();
2433
2434        /*
2435         * We own tsk->cpus_allowed, nobody can change it under us.
2436         *
2437         * But we used cs && cs->cpus_allowed lockless and thus can
2438         * race with cgroup_attach_task() or update_cpumask() and get
2439         * the wrong tsk->cpus_allowed. However, both cases imply the
2440         * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
2441         * which takes task_rq_lock().
2442         *
2443         * If we are called after it dropped the lock we must see all
2444         * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
2445         * set any mask even if it is not right from task_cs() pov,
2446         * the pending set_cpus_allowed_ptr() will fix things.
2447         *
2448         * select_fallback_rq() will fix things ups and set cpu_possible_mask
2449         * if required.
2450         */
2451}
2452
2453void __init cpuset_init_current_mems_allowed(void)
2454{
2455        nodes_setall(current->mems_allowed);
2456}
2457
2458/**
2459 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
2460 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
2461 *
2462 * Description: Returns the nodemask_t mems_allowed of the cpuset
2463 * attached to the specified @tsk.  Guaranteed to return some non-empty
2464 * subset of node_states[N_MEMORY], even if this means going outside the
2465 * tasks cpuset.
2466 **/
2467
2468nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
2469{
2470        nodemask_t mask;
2471        unsigned long flags;
2472
2473        spin_lock_irqsave(&callback_lock, flags);
2474        rcu_read_lock();
2475        guarantee_online_mems(task_cs(tsk), &mask);
2476        rcu_read_unlock();
2477        spin_unlock_irqrestore(&callback_lock, flags);
2478
2479        return mask;
2480}
2481
2482/**
2483 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
2484 * @nodemask: the nodemask to be checked
2485 *
2486 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
2487 */
2488int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
2489{
2490        return nodes_intersects(*nodemask, current->mems_allowed);
2491}
2492
2493/*
2494 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
2495 * mem_hardwall ancestor to the specified cpuset.  Call holding
2496 * callback_lock.  If no ancestor is mem_exclusive or mem_hardwall
2497 * (an unusual configuration), then returns the root cpuset.
2498 */
2499static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
2500{
2501        while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
2502                cs = parent_cs(cs);
2503        return cs;
2504}
2505
2506/**
2507 * cpuset_node_allowed - Can we allocate on a memory node?
2508 * @node: is this an allowed node?
2509 * @gfp_mask: memory allocation flags
2510 *
2511 * If we're in interrupt, yes, we can always allocate.  If @node is set in
2512 * current's mems_allowed, yes.  If it's not a __GFP_HARDWALL request and this
2513 * node is set in the nearest hardwalled cpuset ancestor to current's cpuset,
2514 * yes.  If current has access to memory reserves due to TIF_MEMDIE, yes.
2515 * Otherwise, no.
2516 *
2517 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2518 * and do not allow allocations outside the current tasks cpuset
2519 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2520 * GFP_KERNEL allocations are not so marked, so can escape to the
2521 * nearest enclosing hardwalled ancestor cpuset.
2522 *
2523 * Scanning up parent cpusets requires callback_lock.  The
2524 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
2525 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
2526 * current tasks mems_allowed came up empty on the first pass over
2527 * the zonelist.  So only GFP_KERNEL allocations, if all nodes in the
2528 * cpuset are short of memory, might require taking the callback_lock.
2529 *
2530 * The first call here from mm/page_alloc:get_page_from_freelist()
2531 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
2532 * so no allocation on a node outside the cpuset is allowed (unless
2533 * in interrupt, of course).
2534 *
2535 * The second pass through get_page_from_freelist() doesn't even call
2536 * here for GFP_ATOMIC calls.  For those calls, the __alloc_pages()
2537 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
2538 * in alloc_flags.  That logic and the checks below have the combined
2539 * affect that:
2540 *      in_interrupt - any node ok (current task context irrelevant)
2541 *      GFP_ATOMIC   - any node ok
2542 *      TIF_MEMDIE   - any node ok
2543 *      GFP_KERNEL   - any node in enclosing hardwalled cpuset ok
2544 *      GFP_USER     - only nodes in current tasks mems allowed ok.
2545 */
2546bool __cpuset_node_allowed(int node, gfp_t gfp_mask)
2547{
2548        struct cpuset *cs;              /* current cpuset ancestors */
2549        int allowed;                    /* is allocation in zone z allowed? */
2550        unsigned long flags;
2551
2552        if (in_interrupt())
2553                return true;
2554        if (node_isset(node, current->mems_allowed))
2555                return true;
2556        /*
2557         * Allow tasks that have access to memory reserves because they have
2558         * been OOM killed to get memory anywhere.
2559         */
2560        if (unlikely(test_thread_flag(TIF_MEMDIE)))
2561                return true;
2562        if (gfp_mask & __GFP_HARDWALL)  /* If hardwall request, stop here */
2563                return false;
2564
2565        if (current->flags & PF_EXITING) /* Let dying task have memory */
2566                return true;
2567
2568        /* Not hardwall and node outside mems_allowed: scan up cpusets */
2569        spin_lock_irqsave(&callback_lock, flags);
2570
2571        rcu_read_lock();
2572        cs = nearest_hardwall_ancestor(task_cs(current));
2573        allowed = node_isset(node, cs->mems_allowed);
2574        rcu_read_unlock();
2575
2576        spin_unlock_irqrestore(&callback_lock, flags);
2577        return allowed;
2578}
2579
2580/**
2581 * cpuset_mem_spread_node() - On which node to begin search for a file page
2582 * cpuset_slab_spread_node() - On which node to begin search for a slab page
2583 *
2584 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
2585 * tasks in a cpuset with is_spread_page or is_spread_slab set),
2586 * and if the memory allocation used cpuset_mem_spread_node()
2587 * to determine on which node to start looking, as it will for
2588 * certain page cache or slab cache pages such as used for file
2589 * system buffers and inode caches, then instead of starting on the
2590 * local node to look for a free page, rather spread the starting
2591 * node around the tasks mems_allowed nodes.
2592 *
2593 * We don't have to worry about the returned node being offline
2594 * because "it can't happen", and even if it did, it would be ok.
2595 *
2596 * The routines calling guarantee_online_mems() are careful to
2597 * only set nodes in task->mems_allowed that are online.  So it
2598 * should not be possible for the following code to return an
2599 * offline node.  But if it did, that would be ok, as this routine
2600 * is not returning the node where the allocation must be, only
2601 * the node where the search should start.  The zonelist passed to
2602 * __alloc_pages() will include all nodes.  If the slab allocator
2603 * is passed an offline node, it will fall back to the local node.
2604 * See kmem_cache_alloc_node().
2605 */
2606
2607static int cpuset_spread_node(int *rotor)
2608{
2609        return *rotor = next_node_in(*rotor, current->mems_allowed);
2610}
2611
2612int cpuset_mem_spread_node(void)
2613{
2614        if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
2615                current->cpuset_mem_spread_rotor =
2616                        node_random(&current->mems_allowed);
2617
2618        return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
2619}
2620
2621int cpuset_slab_spread_node(void)
2622{
2623        if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
2624                current->cpuset_slab_spread_rotor =
2625                        node_random(&current->mems_allowed);
2626
2627        return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
2628}
2629
2630EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
2631
2632/**
2633 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
2634 * @tsk1: pointer to task_struct of some task.
2635 * @tsk2: pointer to task_struct of some other task.
2636 *
2637 * Description: Return true if @tsk1's mems_allowed intersects the
2638 * mems_allowed of @tsk2.  Used by the OOM killer to determine if
2639 * one of the task's memory usage might impact the memory available
2640 * to the other.
2641 **/
2642
2643int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
2644                                   const struct task_struct *tsk2)
2645{
2646        return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2647}
2648
2649/**
2650 * cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed
2651 *
2652 * Description: Prints current's name, cpuset name, and cached copy of its
2653 * mems_allowed to the kernel log.
2654 */
2655void cpuset_print_current_mems_allowed(void)
2656{
2657        struct cgroup *cgrp;
2658
2659        rcu_read_lock();
2660
2661        cgrp = task_cs(current)->css.cgroup;
2662        pr_info("%s cpuset=", current->comm);
2663        pr_cont_cgroup_name(cgrp);
2664        pr_cont(" mems_allowed=%*pbl\n",
2665                nodemask_pr_args(&current->mems_allowed));
2666
2667        rcu_read_unlock();
2668}
2669
2670/*
2671 * Collection of memory_pressure is suppressed unless
2672 * this flag is enabled by writing "1" to the special
2673 * cpuset file 'memory_pressure_enabled' in the root cpuset.
2674 */
2675
2676int cpuset_memory_pressure_enabled __read_mostly;
2677
2678/**
2679 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
2680 *
2681 * Keep a running average of the rate of synchronous (direct)
2682 * page reclaim efforts initiated by tasks in each cpuset.
2683 *
2684 * This represents the rate at which some task in the cpuset
2685 * ran low on memory on all nodes it was allowed to use, and
2686 * had to enter the kernels page reclaim code in an effort to
2687 * create more free memory by tossing clean pages or swapping
2688 * or writing dirty pages.
2689 *
2690 * Display to user space in the per-cpuset read-only file
2691 * "memory_pressure".  Value displayed is an integer
2692 * representing the recent rate of entry into the synchronous
2693 * (direct) page reclaim by any task attached to the cpuset.
2694 **/
2695
2696void __cpuset_memory_pressure_bump(void)
2697{
2698        rcu_read_lock();
2699        fmeter_markevent(&task_cs(current)->fmeter);
2700        rcu_read_unlock();
2701}
2702
2703#ifdef CONFIG_PROC_PID_CPUSET
2704/*
2705 * proc_cpuset_show()
2706 *  - Print tasks cpuset path into seq_file.
2707 *  - Used for /proc/<pid>/cpuset.
2708 *  - No need to task_lock(tsk) on this tsk->cpuset reference, as it
2709 *    doesn't really matter if tsk->cpuset changes after we read it,
2710 *    and we take cpuset_mutex, keeping cpuset_attach() from changing it
2711 *    anyway.
2712 */
2713int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
2714                     struct pid *pid, struct task_struct *tsk)
2715{
2716        char *buf, *p;
2717        struct cgroup_subsys_state *css;
2718        int retval;
2719
2720        retval = -ENOMEM;
2721        buf = kmalloc(PATH_MAX, GFP_KERNEL);
2722        if (!buf)
2723                goto out;
2724
2725        retval = -ENAMETOOLONG;
2726        css = task_get_css(tsk, cpuset_cgrp_id);
2727        p = cgroup_path_ns(css->cgroup, buf, PATH_MAX,
2728                           current->nsproxy->cgroup_ns);
2729        css_put(css);
2730        if (!p)
2731                goto out_free;
2732        seq_puts(m, p);
2733        seq_putc(m, '\n');
2734        retval = 0;
2735out_free:
2736        kfree(buf);
2737out:
2738        return retval;
2739}
2740#endif /* CONFIG_PROC_PID_CPUSET */
2741
2742/* Display task mems_allowed in /proc/<pid>/status file. */
2743void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
2744{
2745        seq_printf(m, "Mems_allowed:\t%*pb\n",
2746                   nodemask_pr_args(&task->mems_allowed));
2747        seq_printf(m, "Mems_allowed_list:\t%*pbl\n",
2748                   nodemask_pr_args(&task->mems_allowed));
2749}
2750
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