linux/kernel/cpuset.c
<<
>>
Prefs
   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/backing-dev.h>
  55#include <linux/sort.h>
  56
  57#include <asm/uaccess.h>
  58#include <linux/atomic.h>
  59#include <linux/mutex.h>
  60#include <linux/workqueue.h>
  61#include <linux/cgroup.h>
  62#include <linux/wait.h>
  63
  64struct static_key cpusets_enabled_key __read_mostly = STATIC_KEY_INIT_FALSE;
  65
  66/* See "Frequency meter" comments, below. */
  67
  68struct fmeter {
  69        int cnt;                /* unprocessed events count */
  70        int val;                /* most recent output value */
  71        time_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
 289/*
 290 * CPU / memory hotplug is handled asynchronously.
 291 */
 292static void cpuset_hotplug_workfn(struct work_struct *work);
 293static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
 294
 295static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
 296
 297/*
 298 * This is ugly, but preserves the userspace API for existing cpuset
 299 * users. If someone tries to mount the "cpuset" filesystem, we
 300 * silently switch it to mount "cgroup" instead
 301 */
 302static struct dentry *cpuset_mount(struct file_system_type *fs_type,
 303                         int flags, const char *unused_dev_name, void *data)
 304{
 305        struct file_system_type *cgroup_fs = get_fs_type("cgroup");
 306        struct dentry *ret = ERR_PTR(-ENODEV);
 307        if (cgroup_fs) {
 308                char mountopts[] =
 309                        "cpuset,noprefix,"
 310                        "release_agent=/sbin/cpuset_release_agent";
 311                ret = cgroup_fs->mount(cgroup_fs, flags,
 312                                           unused_dev_name, mountopts);
 313                put_filesystem(cgroup_fs);
 314        }
 315        return ret;
 316}
 317
 318static struct file_system_type cpuset_fs_type = {
 319        .name = "cpuset",
 320        .mount = cpuset_mount,
 321};
 322
 323/*
 324 * Return in pmask the portion of a cpusets's cpus_allowed that
 325 * are online.  If none are online, walk up the cpuset hierarchy
 326 * until we find one that does have some online cpus.  The top
 327 * cpuset always has some cpus online.
 328 *
 329 * One way or another, we guarantee to return some non-empty subset
 330 * of cpu_online_mask.
 331 *
 332 * Call with callback_lock or cpuset_mutex held.
 333 */
 334static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
 335{
 336        while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask))
 337                cs = parent_cs(cs);
 338        cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
 339}
 340
 341/*
 342 * Return in *pmask the portion of a cpusets's mems_allowed that
 343 * are online, with memory.  If none are online with memory, walk
 344 * up the cpuset hierarchy until we find one that does have some
 345 * online mems.  The top cpuset always has some mems online.
 346 *
 347 * One way or another, we guarantee to return some non-empty subset
 348 * of node_states[N_MEMORY].
 349 *
 350 * Call with callback_lock or cpuset_mutex held.
 351 */
 352static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
 353{
 354        while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
 355                cs = parent_cs(cs);
 356        nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
 357}
 358
 359/*
 360 * update task's spread flag if cpuset's page/slab spread flag is set
 361 *
 362 * Call with callback_lock or cpuset_mutex held.
 363 */
 364static void cpuset_update_task_spread_flag(struct cpuset *cs,
 365                                        struct task_struct *tsk)
 366{
 367        if (is_spread_page(cs))
 368                task_set_spread_page(tsk);
 369        else
 370                task_clear_spread_page(tsk);
 371
 372        if (is_spread_slab(cs))
 373                task_set_spread_slab(tsk);
 374        else
 375                task_clear_spread_slab(tsk);
 376}
 377
 378/*
 379 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
 380 *
 381 * One cpuset is a subset of another if all its allowed CPUs and
 382 * Memory Nodes are a subset of the other, and its exclusive flags
 383 * are only set if the other's are set.  Call holding cpuset_mutex.
 384 */
 385
 386static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
 387{
 388        return  cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
 389                nodes_subset(p->mems_allowed, q->mems_allowed) &&
 390                is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
 391                is_mem_exclusive(p) <= is_mem_exclusive(q);
 392}
 393
 394/**
 395 * alloc_trial_cpuset - allocate a trial cpuset
 396 * @cs: the cpuset that the trial cpuset duplicates
 397 */
 398static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
 399{
 400        struct cpuset *trial;
 401
 402        trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
 403        if (!trial)
 404                return NULL;
 405
 406        if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL))
 407                goto free_cs;
 408        if (!alloc_cpumask_var(&trial->effective_cpus, GFP_KERNEL))
 409                goto free_cpus;
 410
 411        cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
 412        cpumask_copy(trial->effective_cpus, cs->effective_cpus);
 413        return trial;
 414
 415free_cpus:
 416        free_cpumask_var(trial->cpus_allowed);
 417free_cs:
 418        kfree(trial);
 419        return NULL;
 420}
 421
 422/**
 423 * free_trial_cpuset - free the trial cpuset
 424 * @trial: the trial cpuset to be freed
 425 */
 426static void free_trial_cpuset(struct cpuset *trial)
 427{
 428        free_cpumask_var(trial->effective_cpus);
 429        free_cpumask_var(trial->cpus_allowed);
 430        kfree(trial);
 431}
 432
 433/*
 434 * validate_change() - Used to validate that any proposed cpuset change
 435 *                     follows the structural rules for cpusets.
 436 *
 437 * If we replaced the flag and mask values of the current cpuset
 438 * (cur) with those values in the trial cpuset (trial), would
 439 * our various subset and exclusive rules still be valid?  Presumes
 440 * cpuset_mutex held.
 441 *
 442 * 'cur' is the address of an actual, in-use cpuset.  Operations
 443 * such as list traversal that depend on the actual address of the
 444 * cpuset in the list must use cur below, not trial.
 445 *
 446 * 'trial' is the address of bulk structure copy of cur, with
 447 * perhaps one or more of the fields cpus_allowed, mems_allowed,
 448 * or flags changed to new, trial values.
 449 *
 450 * Return 0 if valid, -errno if not.
 451 */
 452
 453static int validate_change(struct cpuset *cur, struct cpuset *trial)
 454{
 455        struct cgroup_subsys_state *css;
 456        struct cpuset *c, *par;
 457        int ret;
 458
 459        rcu_read_lock();
 460
 461        /* Each of our child cpusets must be a subset of us */
 462        ret = -EBUSY;
 463        cpuset_for_each_child(c, css, cur)
 464                if (!is_cpuset_subset(c, trial))
 465                        goto out;
 466
 467        /* Remaining checks don't apply to root cpuset */
 468        ret = 0;
 469        if (cur == &top_cpuset)
 470                goto out;
 471
 472        par = parent_cs(cur);
 473
 474        /* On legacy hiearchy, we must be a subset of our parent cpuset. */
 475        ret = -EACCES;
 476        if (!cgroup_on_dfl(cur->css.cgroup) && !is_cpuset_subset(trial, par))
 477                goto out;
 478
 479        /*
 480         * If either I or some sibling (!= me) is exclusive, we can't
 481         * overlap
 482         */
 483        ret = -EINVAL;
 484        cpuset_for_each_child(c, css, par) {
 485                if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
 486                    c != cur &&
 487                    cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
 488                        goto out;
 489                if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
 490                    c != cur &&
 491                    nodes_intersects(trial->mems_allowed, c->mems_allowed))
 492                        goto out;
 493        }
 494
 495        /*
 496         * Cpusets with tasks - existing or newly being attached - can't
 497         * be changed to have empty cpus_allowed or mems_allowed.
 498         */
 499        ret = -ENOSPC;
 500        if ((cgroup_has_tasks(cur->css.cgroup) || cur->attach_in_progress)) {
 501                if (!cpumask_empty(cur->cpus_allowed) &&
 502                    cpumask_empty(trial->cpus_allowed))
 503                        goto out;
 504                if (!nodes_empty(cur->mems_allowed) &&
 505                    nodes_empty(trial->mems_allowed))
 506                        goto out;
 507        }
 508
 509        /*
 510         * We can't shrink if we won't have enough room for SCHED_DEADLINE
 511         * tasks.
 512         */
 513        ret = -EBUSY;
 514        if (is_cpu_exclusive(cur) &&
 515            !cpuset_cpumask_can_shrink(cur->cpus_allowed,
 516                                       trial->cpus_allowed))
 517                goto out;
 518
 519        ret = 0;
 520out:
 521        rcu_read_unlock();
 522        return ret;
 523}
 524
 525#ifdef CONFIG_SMP
 526/*
 527 * Helper routine for generate_sched_domains().
 528 * Do cpusets a, b have overlapping effective cpus_allowed masks?
 529 */
 530static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
 531{
 532        return cpumask_intersects(a->effective_cpus, b->effective_cpus);
 533}
 534
 535static void
 536update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
 537{
 538        if (dattr->relax_domain_level < c->relax_domain_level)
 539                dattr->relax_domain_level = c->relax_domain_level;
 540        return;
 541}
 542
 543static void update_domain_attr_tree(struct sched_domain_attr *dattr,
 544                                    struct cpuset *root_cs)
 545{
 546        struct cpuset *cp;
 547        struct cgroup_subsys_state *pos_css;
 548
 549        rcu_read_lock();
 550        cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
 551                if (cp == root_cs)
 552                        continue;
 553
 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        struct sched_domain_attr *dattr;  /* attributes for custom domains */
 629        int ndoms = 0;          /* number of sched domains in result */
 630        int nslot;              /* next empty doms[] struct cpumask slot */
 631        struct cgroup_subsys_state *pos_css;
 632
 633        doms = NULL;
 634        dattr = NULL;
 635        csa = NULL;
 636
 637        /* Special case for the 99% of systems with one, full, sched domain */
 638        if (is_sched_load_balance(&top_cpuset)) {
 639                ndoms = 1;
 640                doms = alloc_sched_domains(ndoms);
 641                if (!doms)
 642                        goto done;
 643
 644                dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
 645                if (dattr) {
 646                        *dattr = SD_ATTR_INIT;
 647                        update_domain_attr_tree(dattr, &top_cpuset);
 648                }
 649                cpumask_copy(doms[0], top_cpuset.effective_cpus);
 650
 651                goto done;
 652        }
 653
 654        csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL);
 655        if (!csa)
 656                goto done;
 657        csn = 0;
 658
 659        rcu_read_lock();
 660        cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
 661                if (cp == &top_cpuset)
 662                        continue;
 663                /*
 664                 * Continue traversing beyond @cp iff @cp has some CPUs and
 665                 * isn't load balancing.  The former is obvious.  The
 666                 * latter: All child cpusets contain a subset of the
 667                 * parent's cpus, so just skip them, and then we call
 668                 * update_domain_attr_tree() to calc relax_domain_level of
 669                 * the corresponding sched domain.
 670                 */
 671                if (!cpumask_empty(cp->cpus_allowed) &&
 672                    !is_sched_load_balance(cp))
 673                        continue;
 674
 675                if (is_sched_load_balance(cp))
 676                        csa[csn++] = cp;
 677
 678                /* skip @cp's subtree */
 679                pos_css = css_rightmost_descendant(pos_css);
 680        }
 681        rcu_read_unlock();
 682
 683        for (i = 0; i < csn; i++)
 684                csa[i]->pn = i;
 685        ndoms = csn;
 686
 687restart:
 688        /* Find the best partition (set of sched domains) */
 689        for (i = 0; i < csn; i++) {
 690                struct cpuset *a = csa[i];
 691                int apn = a->pn;
 692
 693                for (j = 0; j < csn; j++) {
 694                        struct cpuset *b = csa[j];
 695                        int bpn = b->pn;
 696
 697                        if (apn != bpn && cpusets_overlap(a, b)) {
 698                                for (k = 0; k < csn; k++) {
 699                                        struct cpuset *c = csa[k];
 700
 701                                        if (c->pn == bpn)
 702                                                c->pn = apn;
 703                                }
 704                                ndoms--;        /* one less element */
 705                                goto restart;
 706                        }
 707                }
 708        }
 709
 710        /*
 711         * Now we know how many domains to create.
 712         * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
 713         */
 714        doms = alloc_sched_domains(ndoms);
 715        if (!doms)
 716                goto done;
 717
 718        /*
 719         * The rest of the code, including the scheduler, can deal with
 720         * dattr==NULL case. No need to abort if alloc fails.
 721         */
 722        dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
 723
 724        for (nslot = 0, i = 0; i < csn; i++) {
 725                struct cpuset *a = csa[i];
 726                struct cpumask *dp;
 727                int apn = a->pn;
 728
 729                if (apn < 0) {
 730                        /* Skip completed partitions */
 731                        continue;
 732                }
 733
 734                dp = doms[nslot];
 735
 736                if (nslot == ndoms) {
 737                        static int warnings = 10;
 738                        if (warnings) {
 739                                pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",
 740                                        nslot, ndoms, csn, i, apn);
 741                                warnings--;
 742                        }
 743                        continue;
 744                }
 745
 746                cpumask_clear(dp);
 747                if (dattr)
 748                        *(dattr + nslot) = SD_ATTR_INIT;
 749                for (j = i; j < csn; j++) {
 750                        struct cpuset *b = csa[j];
 751
 752                        if (apn == b->pn) {
 753                                cpumask_or(dp, dp, b->effective_cpus);
 754                                if (dattr)
 755                                        update_domain_attr_tree(dattr + nslot, b);
 756
 757                                /* Done with this partition */
 758                                b->pn = -1;
 759                        }
 760                }
 761                nslot++;
 762        }
 763        BUG_ON(nslot != ndoms);
 764
 765done:
 766        kfree(csa);
 767
 768        /*
 769         * Fallback to the default domain if kmalloc() failed.
 770         * See comments in partition_sched_domains().
 771         */
 772        if (doms == NULL)
 773                ndoms = 1;
 774
 775        *domains    = doms;
 776        *attributes = dattr;
 777        return ndoms;
 778}
 779
 780/*
 781 * Rebuild scheduler domains.
 782 *
 783 * If the flag 'sched_load_balance' of any cpuset with non-empty
 784 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
 785 * which has that flag enabled, or if any cpuset with a non-empty
 786 * 'cpus' is removed, then call this routine to rebuild the
 787 * scheduler's dynamic sched domains.
 788 *
 789 * Call with cpuset_mutex held.  Takes get_online_cpus().
 790 */
 791static void rebuild_sched_domains_locked(void)
 792{
 793        struct sched_domain_attr *attr;
 794        cpumask_var_t *doms;
 795        int ndoms;
 796
 797        lockdep_assert_held(&cpuset_mutex);
 798        get_online_cpus();
 799
 800        /*
 801         * We have raced with CPU hotplug. Don't do anything to avoid
 802         * passing doms with offlined cpu to partition_sched_domains().
 803         * Anyways, hotplug work item will rebuild sched domains.
 804         */
 805        if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
 806                goto out;
 807
 808        /* Generate domain masks and attrs */
 809        ndoms = generate_sched_domains(&doms, &attr);
 810
 811        /* Have scheduler rebuild the domains */
 812        partition_sched_domains(ndoms, doms, attr);
 813out:
 814        put_online_cpus();
 815}
 816#else /* !CONFIG_SMP */
 817static void rebuild_sched_domains_locked(void)
 818{
 819}
 820#endif /* CONFIG_SMP */
 821
 822void rebuild_sched_domains(void)
 823{
 824        mutex_lock(&cpuset_mutex);
 825        rebuild_sched_domains_locked();
 826        mutex_unlock(&cpuset_mutex);
 827}
 828
 829/**
 830 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
 831 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
 832 *
 833 * Iterate through each task of @cs updating its cpus_allowed to the
 834 * effective cpuset's.  As this function is called with cpuset_mutex held,
 835 * cpuset membership stays stable.
 836 */
 837static void update_tasks_cpumask(struct cpuset *cs)
 838{
 839        struct css_task_iter it;
 840        struct task_struct *task;
 841
 842        css_task_iter_start(&cs->css, &it);
 843        while ((task = css_task_iter_next(&it)))
 844                set_cpus_allowed_ptr(task, cs->effective_cpus);
 845        css_task_iter_end(&it);
 846}
 847
 848/*
 849 * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
 850 * @cs: the cpuset to consider
 851 * @new_cpus: temp variable for calculating new effective_cpus
 852 *
 853 * When congifured cpumask is changed, the effective cpumasks of this cpuset
 854 * and all its descendants need to be updated.
 855 *
 856 * On legacy hierachy, effective_cpus will be the same with cpu_allowed.
 857 *
 858 * Called with cpuset_mutex held
 859 */
 860static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
 861{
 862        struct cpuset *cp;
 863        struct cgroup_subsys_state *pos_css;
 864        bool need_rebuild_sched_domains = false;
 865
 866        rcu_read_lock();
 867        cpuset_for_each_descendant_pre(cp, pos_css, cs) {
 868                struct cpuset *parent = parent_cs(cp);
 869
 870                cpumask_and(new_cpus, cp->cpus_allowed, parent->effective_cpus);
 871
 872                /*
 873                 * If it becomes empty, inherit the effective mask of the
 874                 * parent, which is guaranteed to have some CPUs.
 875                 */
 876                if (cpumask_empty(new_cpus))
 877                        cpumask_copy(new_cpus, parent->effective_cpus);
 878
 879                /* Skip the whole subtree if the cpumask remains the same. */
 880                if (cpumask_equal(new_cpus, cp->effective_cpus)) {
 881                        pos_css = css_rightmost_descendant(pos_css);
 882                        continue;
 883                }
 884
 885                if (!css_tryget_online(&cp->css))
 886                        continue;
 887                rcu_read_unlock();
 888
 889                spin_lock_irq(&callback_lock);
 890                cpumask_copy(cp->effective_cpus, new_cpus);
 891                spin_unlock_irq(&callback_lock);
 892
 893                WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
 894                        !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
 895
 896                update_tasks_cpumask(cp);
 897
 898                /*
 899                 * If the effective cpumask of any non-empty cpuset is changed,
 900                 * we need to rebuild sched domains.
 901                 */
 902                if (!cpumask_empty(cp->cpus_allowed) &&
 903                    is_sched_load_balance(cp))
 904                        need_rebuild_sched_domains = true;
 905
 906                rcu_read_lock();
 907                css_put(&cp->css);
 908        }
 909        rcu_read_unlock();
 910
 911        if (need_rebuild_sched_domains)
 912                rebuild_sched_domains_locked();
 913}
 914
 915/**
 916 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
 917 * @cs: the cpuset to consider
 918 * @trialcs: trial cpuset
 919 * @buf: buffer of cpu numbers written to this cpuset
 920 */
 921static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
 922                          const char *buf)
 923{
 924        int retval;
 925
 926        /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
 927        if (cs == &top_cpuset)
 928                return -EACCES;
 929
 930        /*
 931         * An empty cpus_allowed is ok only if the cpuset has no tasks.
 932         * Since cpulist_parse() fails on an empty mask, we special case
 933         * that parsing.  The validate_change() call ensures that cpusets
 934         * with tasks have cpus.
 935         */
 936        if (!*buf) {
 937                cpumask_clear(trialcs->cpus_allowed);
 938        } else {
 939                retval = cpulist_parse(buf, trialcs->cpus_allowed);
 940                if (retval < 0)
 941                        return retval;
 942
 943                if (!cpumask_subset(trialcs->cpus_allowed,
 944                                    top_cpuset.cpus_allowed))
 945                        return -EINVAL;
 946        }
 947
 948        /* Nothing to do if the cpus didn't change */
 949        if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
 950                return 0;
 951
 952        retval = validate_change(cs, trialcs);
 953        if (retval < 0)
 954                return retval;
 955
 956        spin_lock_irq(&callback_lock);
 957        cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
 958        spin_unlock_irq(&callback_lock);
 959
 960        /* use trialcs->cpus_allowed as a temp variable */
 961        update_cpumasks_hier(cs, trialcs->cpus_allowed);
 962        return 0;
 963}
 964
 965/*
 966 * cpuset_migrate_mm
 967 *
 968 *    Migrate memory region from one set of nodes to another.
 969 *
 970 *    Temporarilly set tasks mems_allowed to target nodes of migration,
 971 *    so that the migration code can allocate pages on these nodes.
 972 *
 973 *    While the mm_struct we are migrating is typically from some
 974 *    other task, the task_struct mems_allowed that we are hacking
 975 *    is for our current task, which must allocate new pages for that
 976 *    migrating memory region.
 977 */
 978
 979static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
 980                                                        const nodemask_t *to)
 981{
 982        struct task_struct *tsk = current;
 983
 984        tsk->mems_allowed = *to;
 985
 986        do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
 987
 988        rcu_read_lock();
 989        guarantee_online_mems(task_cs(tsk), &tsk->mems_allowed);
 990        rcu_read_unlock();
 991}
 992
 993/*
 994 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
 995 * @tsk: the task to change
 996 * @newmems: new nodes that the task will be set
 997 *
 998 * In order to avoid seeing no nodes if the old and new nodes are disjoint,
 999 * we structure updates as setting all new allowed nodes, then clearing newly
1000 * disallowed ones.
1001 */
1002static void cpuset_change_task_nodemask(struct task_struct *tsk,
1003                                        nodemask_t *newmems)
1004{
1005        bool need_loop;
1006
1007        /*
1008         * Allow tasks that have access to memory reserves because they have
1009         * been OOM killed to get memory anywhere.
1010         */
1011        if (unlikely(test_thread_flag(TIF_MEMDIE)))
1012                return;
1013        if (current->flags & PF_EXITING) /* Let dying task have memory */
1014                return;
1015
1016        task_lock(tsk);
1017        /*
1018         * Determine if a loop is necessary if another thread is doing
1019         * read_mems_allowed_begin().  If at least one node remains unchanged and
1020         * tsk does not have a mempolicy, then an empty nodemask will not be
1021         * possible when mems_allowed is larger than a word.
1022         */
1023        need_loop = task_has_mempolicy(tsk) ||
1024                        !nodes_intersects(*newmems, tsk->mems_allowed);
1025
1026        if (need_loop) {
1027                local_irq_disable();
1028                write_seqcount_begin(&tsk->mems_allowed_seq);
1029        }
1030
1031        nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
1032        mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
1033
1034        mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
1035        tsk->mems_allowed = *newmems;
1036
1037        if (need_loop) {
1038                write_seqcount_end(&tsk->mems_allowed_seq);
1039                local_irq_enable();
1040        }
1041
1042        task_unlock(tsk);
1043}
1044
1045static void *cpuset_being_rebound;
1046
1047/**
1048 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1049 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1050 *
1051 * Iterate through each task of @cs updating its mems_allowed to the
1052 * effective cpuset's.  As this function is called with cpuset_mutex held,
1053 * cpuset membership stays stable.
1054 */
1055static void update_tasks_nodemask(struct cpuset *cs)
1056{
1057        static nodemask_t newmems;      /* protected by cpuset_mutex */
1058        struct css_task_iter it;
1059        struct task_struct *task;
1060
1061        cpuset_being_rebound = cs;              /* causes mpol_dup() rebind */
1062
1063        guarantee_online_mems(cs, &newmems);
1064
1065        /*
1066         * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
1067         * take while holding tasklist_lock.  Forks can happen - the
1068         * mpol_dup() cpuset_being_rebound check will catch such forks,
1069         * and rebind their vma mempolicies too.  Because we still hold
1070         * the global cpuset_mutex, we know that no other rebind effort
1071         * will be contending for the global variable cpuset_being_rebound.
1072         * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1073         * is idempotent.  Also migrate pages in each mm to new nodes.
1074         */
1075        css_task_iter_start(&cs->css, &it);
1076        while ((task = css_task_iter_next(&it))) {
1077                struct mm_struct *mm;
1078                bool migrate;
1079
1080                cpuset_change_task_nodemask(task, &newmems);
1081
1082                mm = get_task_mm(task);
1083                if (!mm)
1084                        continue;
1085
1086                migrate = is_memory_migrate(cs);
1087
1088                mpol_rebind_mm(mm, &cs->mems_allowed);
1089                if (migrate)
1090                        cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
1091                mmput(mm);
1092        }
1093        css_task_iter_end(&it);
1094
1095        /*
1096         * All the tasks' nodemasks have been updated, update
1097         * cs->old_mems_allowed.
1098         */
1099        cs->old_mems_allowed = newmems;
1100
1101        /* We're done rebinding vmas to this cpuset's new mems_allowed. */
1102        cpuset_being_rebound = NULL;
1103}
1104
1105/*
1106 * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree
1107 * @cs: the cpuset to consider
1108 * @new_mems: a temp variable for calculating new effective_mems
1109 *
1110 * When configured nodemask is changed, the effective nodemasks of this cpuset
1111 * and all its descendants need to be updated.
1112 *
1113 * On legacy hiearchy, effective_mems will be the same with mems_allowed.
1114 *
1115 * Called with cpuset_mutex held
1116 */
1117static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
1118{
1119        struct cpuset *cp;
1120        struct cgroup_subsys_state *pos_css;
1121
1122        rcu_read_lock();
1123        cpuset_for_each_descendant_pre(cp, pos_css, cs) {
1124                struct cpuset *parent = parent_cs(cp);
1125
1126                nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
1127
1128                /*
1129                 * If it becomes empty, inherit the effective mask of the
1130                 * parent, which is guaranteed to have some MEMs.
1131                 */
1132                if (nodes_empty(*new_mems))
1133                        *new_mems = parent->effective_mems;
1134
1135                /* Skip the whole subtree if the nodemask remains the same. */
1136                if (nodes_equal(*new_mems, cp->effective_mems)) {
1137                        pos_css = css_rightmost_descendant(pos_css);
1138                        continue;
1139                }
1140
1141                if (!css_tryget_online(&cp->css))
1142                        continue;
1143                rcu_read_unlock();
1144
1145                spin_lock_irq(&callback_lock);
1146                cp->effective_mems = *new_mems;
1147                spin_unlock_irq(&callback_lock);
1148
1149                WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
1150                        !nodes_equal(cp->mems_allowed, cp->effective_mems));
1151
1152                update_tasks_nodemask(cp);
1153
1154                rcu_read_lock();
1155                css_put(&cp->css);
1156        }
1157        rcu_read_unlock();
1158}
1159
1160/*
1161 * Handle user request to change the 'mems' memory placement
1162 * of a cpuset.  Needs to validate the request, update the
1163 * cpusets mems_allowed, and for each task in the cpuset,
1164 * update mems_allowed and rebind task's mempolicy and any vma
1165 * mempolicies and if the cpuset is marked 'memory_migrate',
1166 * migrate the tasks pages to the new memory.
1167 *
1168 * Call with cpuset_mutex held. May take callback_lock during call.
1169 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1170 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
1171 * their mempolicies to the cpusets new mems_allowed.
1172 */
1173static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
1174                           const char *buf)
1175{
1176        int retval;
1177
1178        /*
1179         * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
1180         * it's read-only
1181         */
1182        if (cs == &top_cpuset) {
1183                retval = -EACCES;
1184                goto done;
1185        }
1186
1187        /*
1188         * An empty mems_allowed is ok iff there are no tasks in the cpuset.
1189         * Since nodelist_parse() fails on an empty mask, we special case
1190         * that parsing.  The validate_change() call ensures that cpusets
1191         * with tasks have memory.
1192         */
1193        if (!*buf) {
1194                nodes_clear(trialcs->mems_allowed);
1195        } else {
1196                retval = nodelist_parse(buf, trialcs->mems_allowed);
1197                if (retval < 0)
1198                        goto done;
1199
1200                if (!nodes_subset(trialcs->mems_allowed,
1201                                  top_cpuset.mems_allowed)) {
1202                        retval = -EINVAL;
1203                        goto done;
1204                }
1205        }
1206
1207        if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
1208                retval = 0;             /* Too easy - nothing to do */
1209                goto done;
1210        }
1211        retval = validate_change(cs, trialcs);
1212        if (retval < 0)
1213                goto done;
1214
1215        spin_lock_irq(&callback_lock);
1216        cs->mems_allowed = trialcs->mems_allowed;
1217        spin_unlock_irq(&callback_lock);
1218
1219        /* use trialcs->mems_allowed as a temp variable */
1220        update_nodemasks_hier(cs, &cs->mems_allowed);
1221done:
1222        return retval;
1223}
1224
1225int current_cpuset_is_being_rebound(void)
1226{
1227        int ret;
1228
1229        rcu_read_lock();
1230        ret = task_cs(current) == cpuset_being_rebound;
1231        rcu_read_unlock();
1232
1233        return ret;
1234}
1235
1236static int update_relax_domain_level(struct cpuset *cs, s64 val)
1237{
1238#ifdef CONFIG_SMP
1239        if (val < -1 || val >= sched_domain_level_max)
1240                return -EINVAL;
1241#endif
1242
1243        if (val != cs->relax_domain_level) {
1244                cs->relax_domain_level = val;
1245                if (!cpumask_empty(cs->cpus_allowed) &&
1246                    is_sched_load_balance(cs))
1247                        rebuild_sched_domains_locked();
1248        }
1249
1250        return 0;
1251}
1252
1253/**
1254 * update_tasks_flags - update the spread flags of tasks in the cpuset.
1255 * @cs: the cpuset in which each task's spread flags needs to be changed
1256 *
1257 * Iterate through each task of @cs updating its spread flags.  As this
1258 * function is called with cpuset_mutex held, cpuset membership stays
1259 * stable.
1260 */
1261static void update_tasks_flags(struct cpuset *cs)
1262{
1263        struct css_task_iter it;
1264        struct task_struct *task;
1265
1266        css_task_iter_start(&cs->css, &it);
1267        while ((task = css_task_iter_next(&it)))
1268                cpuset_update_task_spread_flag(cs, task);
1269        css_task_iter_end(&it);
1270}
1271
1272/*
1273 * update_flag - read a 0 or a 1 in a file and update associated flag
1274 * bit:         the bit to update (see cpuset_flagbits_t)
1275 * cs:          the cpuset to update
1276 * turning_on:  whether the flag is being set or cleared
1277 *
1278 * Call with cpuset_mutex held.
1279 */
1280
1281static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1282                       int turning_on)
1283{
1284        struct cpuset *trialcs;
1285        int balance_flag_changed;
1286        int spread_flag_changed;
1287        int err;
1288
1289        trialcs = alloc_trial_cpuset(cs);
1290        if (!trialcs)
1291                return -ENOMEM;
1292
1293        if (turning_on)
1294                set_bit(bit, &trialcs->flags);
1295        else
1296                clear_bit(bit, &trialcs->flags);
1297
1298        err = validate_change(cs, trialcs);
1299        if (err < 0)
1300                goto out;
1301
1302        balance_flag_changed = (is_sched_load_balance(cs) !=
1303                                is_sched_load_balance(trialcs));
1304
1305        spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
1306                        || (is_spread_page(cs) != is_spread_page(trialcs)));
1307
1308        spin_lock_irq(&callback_lock);
1309        cs->flags = trialcs->flags;
1310        spin_unlock_irq(&callback_lock);
1311
1312        if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1313                rebuild_sched_domains_locked();
1314
1315        if (spread_flag_changed)
1316                update_tasks_flags(cs);
1317out:
1318        free_trial_cpuset(trialcs);
1319        return err;
1320}
1321
1322/*
1323 * Frequency meter - How fast is some event occurring?
1324 *
1325 * These routines manage a digitally filtered, constant time based,
1326 * event frequency meter.  There are four routines:
1327 *   fmeter_init() - initialize a frequency meter.
1328 *   fmeter_markevent() - called each time the event happens.
1329 *   fmeter_getrate() - returns the recent rate of such events.
1330 *   fmeter_update() - internal routine used to update fmeter.
1331 *
1332 * A common data structure is passed to each of these routines,
1333 * which is used to keep track of the state required to manage the
1334 * frequency meter and its digital filter.
1335 *
1336 * The filter works on the number of events marked per unit time.
1337 * The filter is single-pole low-pass recursive (IIR).  The time unit
1338 * is 1 second.  Arithmetic is done using 32-bit integers scaled to
1339 * simulate 3 decimal digits of precision (multiplied by 1000).
1340 *
1341 * With an FM_COEF of 933, and a time base of 1 second, the filter
1342 * has a half-life of 10 seconds, meaning that if the events quit
1343 * happening, then the rate returned from the fmeter_getrate()
1344 * will be cut in half each 10 seconds, until it converges to zero.
1345 *
1346 * It is not worth doing a real infinitely recursive filter.  If more
1347 * than FM_MAXTICKS ticks have elapsed since the last filter event,
1348 * just compute FM_MAXTICKS ticks worth, by which point the level
1349 * will be stable.
1350 *
1351 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
1352 * arithmetic overflow in the fmeter_update() routine.
1353 *
1354 * Given the simple 32 bit integer arithmetic used, this meter works
1355 * best for reporting rates between one per millisecond (msec) and
1356 * one per 32 (approx) seconds.  At constant rates faster than one
1357 * per msec it maxes out at values just under 1,000,000.  At constant
1358 * rates between one per msec, and one per second it will stabilize
1359 * to a value N*1000, where N is the rate of events per second.
1360 * At constant rates between one per second and one per 32 seconds,
1361 * it will be choppy, moving up on the seconds that have an event,
1362 * and then decaying until the next event.  At rates slower than
1363 * about one in 32 seconds, it decays all the way back to zero between
1364 * each event.
1365 */
1366
1367#define FM_COEF 933             /* coefficient for half-life of 10 secs */
1368#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
1369#define FM_MAXCNT 1000000       /* limit cnt to avoid overflow */
1370#define FM_SCALE 1000           /* faux fixed point scale */
1371
1372/* Initialize a frequency meter */
1373static void fmeter_init(struct fmeter *fmp)
1374{
1375        fmp->cnt = 0;
1376        fmp->val = 0;
1377        fmp->time = 0;
1378        spin_lock_init(&fmp->lock);
1379}
1380
1381/* Internal meter update - process cnt events and update value */
1382static void fmeter_update(struct fmeter *fmp)
1383{
1384        time_t now = get_seconds();
1385        time_t ticks = now - fmp->time;
1386
1387        if (ticks == 0)
1388                return;
1389
1390        ticks = min(FM_MAXTICKS, ticks);
1391        while (ticks-- > 0)
1392                fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
1393        fmp->time = now;
1394
1395        fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
1396        fmp->cnt = 0;
1397}
1398
1399/* Process any previous ticks, then bump cnt by one (times scale). */
1400static void fmeter_markevent(struct fmeter *fmp)
1401{
1402        spin_lock(&fmp->lock);
1403        fmeter_update(fmp);
1404        fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
1405        spin_unlock(&fmp->lock);
1406}
1407
1408/* Process any previous ticks, then return current value. */
1409static int fmeter_getrate(struct fmeter *fmp)
1410{
1411        int val;
1412
1413        spin_lock(&fmp->lock);
1414        fmeter_update(fmp);
1415        val = fmp->val;
1416        spin_unlock(&fmp->lock);
1417        return val;
1418}
1419
1420static struct cpuset *cpuset_attach_old_cs;
1421
1422/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
1423static int cpuset_can_attach(struct cgroup_subsys_state *css,
1424                             struct cgroup_taskset *tset)
1425{
1426        struct cpuset *cs = css_cs(css);
1427        struct task_struct *task;
1428        int ret;
1429
1430        /* used later by cpuset_attach() */
1431        cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset));
1432
1433        mutex_lock(&cpuset_mutex);
1434
1435        /* allow moving tasks into an empty cpuset if on default hierarchy */
1436        ret = -ENOSPC;
1437        if (!cgroup_on_dfl(css->cgroup) &&
1438            (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
1439                goto out_unlock;
1440
1441        cgroup_taskset_for_each(task, tset) {
1442                ret = task_can_attach(task, cs->cpus_allowed);
1443                if (ret)
1444                        goto out_unlock;
1445                ret = security_task_setscheduler(task);
1446                if (ret)
1447                        goto out_unlock;
1448        }
1449
1450        /*
1451         * Mark attach is in progress.  This makes validate_change() fail
1452         * changes which zero cpus/mems_allowed.
1453         */
1454        cs->attach_in_progress++;
1455        ret = 0;
1456out_unlock:
1457        mutex_unlock(&cpuset_mutex);
1458        return ret;
1459}
1460
1461static void cpuset_cancel_attach(struct cgroup_subsys_state *css,
1462                                 struct cgroup_taskset *tset)
1463{
1464        mutex_lock(&cpuset_mutex);
1465        css_cs(css)->attach_in_progress--;
1466        mutex_unlock(&cpuset_mutex);
1467}
1468
1469/*
1470 * Protected by cpuset_mutex.  cpus_attach is used only by cpuset_attach()
1471 * but we can't allocate it dynamically there.  Define it global and
1472 * allocate from cpuset_init().
1473 */
1474static cpumask_var_t cpus_attach;
1475
1476static void cpuset_attach(struct cgroup_subsys_state *css,
1477                          struct cgroup_taskset *tset)
1478{
1479        /* static buf protected by cpuset_mutex */
1480        static nodemask_t cpuset_attach_nodemask_to;
1481        struct mm_struct *mm;
1482        struct task_struct *task;
1483        struct task_struct *leader = cgroup_taskset_first(tset);
1484        struct cpuset *cs = css_cs(css);
1485        struct cpuset *oldcs = cpuset_attach_old_cs;
1486
1487        mutex_lock(&cpuset_mutex);
1488
1489        /* prepare for attach */
1490        if (cs == &top_cpuset)
1491                cpumask_copy(cpus_attach, cpu_possible_mask);
1492        else
1493                guarantee_online_cpus(cs, cpus_attach);
1494
1495        guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
1496
1497        cgroup_taskset_for_each(task, tset) {
1498                /*
1499                 * can_attach beforehand should guarantee that this doesn't
1500                 * fail.  TODO: have a better way to handle failure here
1501                 */
1502                WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
1503
1504                cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
1505                cpuset_update_task_spread_flag(cs, task);
1506        }
1507
1508        /*
1509         * Change mm, possibly for multiple threads in a threadgroup. This is
1510         * expensive and may sleep.
1511         */
1512        cpuset_attach_nodemask_to = cs->effective_mems;
1513        mm = get_task_mm(leader);
1514        if (mm) {
1515                mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
1516
1517                /*
1518                 * old_mems_allowed is the same with mems_allowed here, except
1519                 * if this task is being moved automatically due to hotplug.
1520                 * In that case @mems_allowed has been updated and is empty,
1521                 * so @old_mems_allowed is the right nodesets that we migrate
1522                 * mm from.
1523                 */
1524                if (is_memory_migrate(cs)) {
1525                        cpuset_migrate_mm(mm, &oldcs->old_mems_allowed,
1526                                          &cpuset_attach_nodemask_to);
1527                }
1528                mmput(mm);
1529        }
1530
1531        cs->old_mems_allowed = cpuset_attach_nodemask_to;
1532
1533        cs->attach_in_progress--;
1534        if (!cs->attach_in_progress)
1535                wake_up(&cpuset_attach_wq);
1536
1537        mutex_unlock(&cpuset_mutex);
1538}
1539
1540/* The various types of files and directories in a cpuset file system */
1541
1542typedef enum {
1543        FILE_MEMORY_MIGRATE,
1544        FILE_CPULIST,
1545        FILE_MEMLIST,
1546        FILE_EFFECTIVE_CPULIST,
1547        FILE_EFFECTIVE_MEMLIST,
1548        FILE_CPU_EXCLUSIVE,
1549        FILE_MEM_EXCLUSIVE,
1550        FILE_MEM_HARDWALL,
1551        FILE_SCHED_LOAD_BALANCE,
1552        FILE_SCHED_RELAX_DOMAIN_LEVEL,
1553        FILE_MEMORY_PRESSURE_ENABLED,
1554        FILE_MEMORY_PRESSURE,
1555        FILE_SPREAD_PAGE,
1556        FILE_SPREAD_SLAB,
1557} cpuset_filetype_t;
1558
1559static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
1560                            u64 val)
1561{
1562        struct cpuset *cs = css_cs(css);
1563        cpuset_filetype_t type = cft->private;
1564        int retval = 0;
1565
1566        mutex_lock(&cpuset_mutex);
1567        if (!is_cpuset_online(cs)) {
1568                retval = -ENODEV;
1569                goto out_unlock;
1570        }
1571
1572        switch (type) {
1573        case FILE_CPU_EXCLUSIVE:
1574                retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
1575                break;
1576        case FILE_MEM_EXCLUSIVE:
1577                retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
1578                break;
1579        case FILE_MEM_HARDWALL:
1580                retval = update_flag(CS_MEM_HARDWALL, cs, val);
1581                break;
1582        case FILE_SCHED_LOAD_BALANCE:
1583                retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1584                break;
1585        case FILE_MEMORY_MIGRATE:
1586                retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1587                break;
1588        case FILE_MEMORY_PRESSURE_ENABLED:
1589                cpuset_memory_pressure_enabled = !!val;
1590                break;
1591        case FILE_MEMORY_PRESSURE:
1592                retval = -EACCES;
1593                break;
1594        case FILE_SPREAD_PAGE:
1595                retval = update_flag(CS_SPREAD_PAGE, cs, val);
1596                break;
1597        case FILE_SPREAD_SLAB:
1598                retval = update_flag(CS_SPREAD_SLAB, cs, val);
1599                break;
1600        default:
1601                retval = -EINVAL;
1602                break;
1603        }
1604out_unlock:
1605        mutex_unlock(&cpuset_mutex);
1606        return retval;
1607}
1608
1609static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
1610                            s64 val)
1611{
1612        struct cpuset *cs = css_cs(css);
1613        cpuset_filetype_t type = cft->private;
1614        int retval = -ENODEV;
1615
1616        mutex_lock(&cpuset_mutex);
1617        if (!is_cpuset_online(cs))
1618                goto out_unlock;
1619
1620        switch (type) {
1621        case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1622                retval = update_relax_domain_level(cs, val);
1623                break;
1624        default:
1625                retval = -EINVAL;
1626                break;
1627        }
1628out_unlock:
1629        mutex_unlock(&cpuset_mutex);
1630        return retval;
1631}
1632
1633/*
1634 * Common handling for a write to a "cpus" or "mems" file.
1635 */
1636static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
1637                                    char *buf, size_t nbytes, loff_t off)
1638{
1639        struct cpuset *cs = css_cs(of_css(of));
1640        struct cpuset *trialcs;
1641        int retval = -ENODEV;
1642
1643        buf = strstrip(buf);
1644
1645        /*
1646         * CPU or memory hotunplug may leave @cs w/o any execution
1647         * resources, in which case the hotplug code asynchronously updates
1648         * configuration and transfers all tasks to the nearest ancestor
1649         * which can execute.
1650         *
1651         * As writes to "cpus" or "mems" may restore @cs's execution
1652         * resources, wait for the previously scheduled operations before
1653         * proceeding, so that we don't end up keep removing tasks added
1654         * after execution capability is restored.
1655         *
1656         * cpuset_hotplug_work calls back into cgroup core via
1657         * cgroup_transfer_tasks() and waiting for it from a cgroupfs
1658         * operation like this one can lead to a deadlock through kernfs
1659         * active_ref protection.  Let's break the protection.  Losing the
1660         * protection is okay as we check whether @cs is online after
1661         * grabbing cpuset_mutex anyway.  This only happens on the legacy
1662         * hierarchies.
1663         */
1664        css_get(&cs->css);
1665        kernfs_break_active_protection(of->kn);
1666        flush_work(&cpuset_hotplug_work);
1667
1668        mutex_lock(&cpuset_mutex);
1669        if (!is_cpuset_online(cs))
1670                goto out_unlock;
1671
1672        trialcs = alloc_trial_cpuset(cs);
1673        if (!trialcs) {
1674                retval = -ENOMEM;
1675                goto out_unlock;
1676        }
1677
1678        switch (of_cft(of)->private) {
1679        case FILE_CPULIST:
1680                retval = update_cpumask(cs, trialcs, buf);
1681                break;
1682        case FILE_MEMLIST:
1683                retval = update_nodemask(cs, trialcs, buf);
1684                break;
1685        default:
1686                retval = -EINVAL;
1687                break;
1688        }
1689
1690        free_trial_cpuset(trialcs);
1691out_unlock:
1692        mutex_unlock(&cpuset_mutex);
1693        kernfs_unbreak_active_protection(of->kn);
1694        css_put(&cs->css);
1695        return retval ?: nbytes;
1696}
1697
1698/*
1699 * These ascii lists should be read in a single call, by using a user
1700 * buffer large enough to hold the entire map.  If read in smaller
1701 * chunks, there is no guarantee of atomicity.  Since the display format
1702 * used, list of ranges of sequential numbers, is variable length,
1703 * and since these maps can change value dynamically, one could read
1704 * gibberish by doing partial reads while a list was changing.
1705 */
1706static int cpuset_common_seq_show(struct seq_file *sf, void *v)
1707{
1708        struct cpuset *cs = css_cs(seq_css(sf));
1709        cpuset_filetype_t type = seq_cft(sf)->private;
1710        ssize_t count;
1711        char *buf, *s;
1712        int ret = 0;
1713
1714        count = seq_get_buf(sf, &buf);
1715        s = buf;
1716
1717        spin_lock_irq(&callback_lock);
1718
1719        switch (type) {
1720        case FILE_CPULIST:
1721                s += cpulist_scnprintf(s, count, cs->cpus_allowed);
1722                break;
1723        case FILE_MEMLIST:
1724                s += nodelist_scnprintf(s, count, cs->mems_allowed);
1725                break;
1726        case FILE_EFFECTIVE_CPULIST:
1727                s += cpulist_scnprintf(s, count, cs->effective_cpus);
1728                break;
1729        case FILE_EFFECTIVE_MEMLIST:
1730                s += nodelist_scnprintf(s, count, cs->effective_mems);
1731                break;
1732        default:
1733                ret = -EINVAL;
1734                goto out_unlock;
1735        }
1736
1737        if (s < buf + count - 1) {
1738                *s++ = '\n';
1739                seq_commit(sf, s - buf);
1740        } else {
1741                seq_commit(sf, -1);
1742        }
1743out_unlock:
1744        spin_unlock_irq(&callback_lock);
1745        return ret;
1746}
1747
1748static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
1749{
1750        struct cpuset *cs = css_cs(css);
1751        cpuset_filetype_t type = cft->private;
1752        switch (type) {
1753        case FILE_CPU_EXCLUSIVE:
1754                return is_cpu_exclusive(cs);
1755        case FILE_MEM_EXCLUSIVE:
1756                return is_mem_exclusive(cs);
1757        case FILE_MEM_HARDWALL:
1758                return is_mem_hardwall(cs);
1759        case FILE_SCHED_LOAD_BALANCE:
1760                return is_sched_load_balance(cs);
1761        case FILE_MEMORY_MIGRATE:
1762                return is_memory_migrate(cs);
1763        case FILE_MEMORY_PRESSURE_ENABLED:
1764                return cpuset_memory_pressure_enabled;
1765        case FILE_MEMORY_PRESSURE:
1766                return fmeter_getrate(&cs->fmeter);
1767        case FILE_SPREAD_PAGE:
1768                return is_spread_page(cs);
1769        case FILE_SPREAD_SLAB:
1770                return is_spread_slab(cs);
1771        default:
1772                BUG();
1773        }
1774
1775        /* Unreachable but makes gcc happy */
1776        return 0;
1777}
1778
1779static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
1780{
1781        struct cpuset *cs = css_cs(css);
1782        cpuset_filetype_t type = cft->private;
1783        switch (type) {
1784        case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1785                return cs->relax_domain_level;
1786        default:
1787                BUG();
1788        }
1789
1790        /* Unrechable but makes gcc happy */
1791        return 0;
1792}
1793
1794
1795/*
1796 * for the common functions, 'private' gives the type of file
1797 */
1798
1799static struct cftype files[] = {
1800        {
1801                .name = "cpus",
1802                .seq_show = cpuset_common_seq_show,
1803                .write = cpuset_write_resmask,
1804                .max_write_len = (100U + 6 * NR_CPUS),
1805                .private = FILE_CPULIST,
1806        },
1807
1808        {
1809                .name = "mems",
1810                .seq_show = cpuset_common_seq_show,
1811                .write = cpuset_write_resmask,
1812                .max_write_len = (100U + 6 * MAX_NUMNODES),
1813                .private = FILE_MEMLIST,
1814        },
1815
1816        {
1817                .name = "effective_cpus",
1818                .seq_show = cpuset_common_seq_show,
1819                .private = FILE_EFFECTIVE_CPULIST,
1820        },
1821
1822        {
1823                .name = "effective_mems",
1824                .seq_show = cpuset_common_seq_show,
1825                .private = FILE_EFFECTIVE_MEMLIST,
1826        },
1827
1828        {
1829                .name = "cpu_exclusive",
1830                .read_u64 = cpuset_read_u64,
1831                .write_u64 = cpuset_write_u64,
1832                .private = FILE_CPU_EXCLUSIVE,
1833        },
1834
1835        {
1836                .name = "mem_exclusive",
1837                .read_u64 = cpuset_read_u64,
1838                .write_u64 = cpuset_write_u64,
1839                .private = FILE_MEM_EXCLUSIVE,
1840        },
1841
1842        {
1843                .name = "mem_hardwall",
1844                .read_u64 = cpuset_read_u64,
1845                .write_u64 = cpuset_write_u64,
1846                .private = FILE_MEM_HARDWALL,
1847        },
1848
1849        {
1850                .name = "sched_load_balance",
1851                .read_u64 = cpuset_read_u64,
1852                .write_u64 = cpuset_write_u64,
1853                .private = FILE_SCHED_LOAD_BALANCE,
1854        },
1855
1856        {
1857                .name = "sched_relax_domain_level",
1858                .read_s64 = cpuset_read_s64,
1859                .write_s64 = cpuset_write_s64,
1860                .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
1861        },
1862
1863        {
1864                .name = "memory_migrate",
1865                .read_u64 = cpuset_read_u64,
1866                .write_u64 = cpuset_write_u64,
1867                .private = FILE_MEMORY_MIGRATE,
1868        },
1869
1870        {
1871                .name = "memory_pressure",
1872                .read_u64 = cpuset_read_u64,
1873                .write_u64 = cpuset_write_u64,
1874                .private = FILE_MEMORY_PRESSURE,
1875                .mode = S_IRUGO,
1876        },
1877
1878        {
1879                .name = "memory_spread_page",
1880                .read_u64 = cpuset_read_u64,
1881                .write_u64 = cpuset_write_u64,
1882                .private = FILE_SPREAD_PAGE,
1883        },
1884
1885        {
1886                .name = "memory_spread_slab",
1887                .read_u64 = cpuset_read_u64,
1888                .write_u64 = cpuset_write_u64,
1889                .private = FILE_SPREAD_SLAB,
1890        },
1891
1892        {
1893                .name = "memory_pressure_enabled",
1894                .flags = CFTYPE_ONLY_ON_ROOT,
1895                .read_u64 = cpuset_read_u64,
1896                .write_u64 = cpuset_write_u64,
1897                .private = FILE_MEMORY_PRESSURE_ENABLED,
1898        },
1899
1900        { }     /* terminate */
1901};
1902
1903/*
1904 *      cpuset_css_alloc - allocate a cpuset css
1905 *      cgrp:   control group that the new cpuset will be part of
1906 */
1907
1908static struct cgroup_subsys_state *
1909cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
1910{
1911        struct cpuset *cs;
1912
1913        if (!parent_css)
1914                return &top_cpuset.css;
1915
1916        cs = kzalloc(sizeof(*cs), GFP_KERNEL);
1917        if (!cs)
1918                return ERR_PTR(-ENOMEM);
1919        if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL))
1920                goto free_cs;
1921        if (!alloc_cpumask_var(&cs->effective_cpus, GFP_KERNEL))
1922                goto free_cpus;
1923
1924        set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1925        cpumask_clear(cs->cpus_allowed);
1926        nodes_clear(cs->mems_allowed);
1927        cpumask_clear(cs->effective_cpus);
1928        nodes_clear(cs->effective_mems);
1929        fmeter_init(&cs->fmeter);
1930        cs->relax_domain_level = -1;
1931
1932        return &cs->css;
1933
1934free_cpus:
1935        free_cpumask_var(cs->cpus_allowed);
1936free_cs:
1937        kfree(cs);
1938        return ERR_PTR(-ENOMEM);
1939}
1940
1941static int cpuset_css_online(struct cgroup_subsys_state *css)
1942{
1943        struct cpuset *cs = css_cs(css);
1944        struct cpuset *parent = parent_cs(cs);
1945        struct cpuset *tmp_cs;
1946        struct cgroup_subsys_state *pos_css;
1947
1948        if (!parent)
1949                return 0;
1950
1951        mutex_lock(&cpuset_mutex);
1952
1953        set_bit(CS_ONLINE, &cs->flags);
1954        if (is_spread_page(parent))
1955                set_bit(CS_SPREAD_PAGE, &cs->flags);
1956        if (is_spread_slab(parent))
1957                set_bit(CS_SPREAD_SLAB, &cs->flags);
1958
1959        cpuset_inc();
1960
1961        spin_lock_irq(&callback_lock);
1962        if (cgroup_on_dfl(cs->css.cgroup)) {
1963                cpumask_copy(cs->effective_cpus, parent->effective_cpus);
1964                cs->effective_mems = parent->effective_mems;
1965        }
1966        spin_unlock_irq(&callback_lock);
1967
1968        if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
1969                goto out_unlock;
1970
1971        /*
1972         * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
1973         * set.  This flag handling is implemented in cgroup core for
1974         * histrical reasons - the flag may be specified during mount.
1975         *
1976         * Currently, if any sibling cpusets have exclusive cpus or mem, we
1977         * refuse to clone the configuration - thereby refusing the task to
1978         * be entered, and as a result refusing the sys_unshare() or
1979         * clone() which initiated it.  If this becomes a problem for some
1980         * users who wish to allow that scenario, then this could be
1981         * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1982         * (and likewise for mems) to the new cgroup.
1983         */
1984        rcu_read_lock();
1985        cpuset_for_each_child(tmp_cs, pos_css, parent) {
1986                if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
1987                        rcu_read_unlock();
1988                        goto out_unlock;
1989                }
1990        }
1991        rcu_read_unlock();
1992
1993        spin_lock_irq(&callback_lock);
1994        cs->mems_allowed = parent->mems_allowed;
1995        cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
1996        spin_unlock_irq(&callback_lock);
1997out_unlock:
1998        mutex_unlock(&cpuset_mutex);
1999        return 0;
2000}
2001
2002/*
2003 * If the cpuset being removed has its flag 'sched_load_balance'
2004 * enabled, then simulate turning sched_load_balance off, which
2005 * will call rebuild_sched_domains_locked().
2006 */
2007
2008static void cpuset_css_offline(struct cgroup_subsys_state *css)
2009{
2010        struct cpuset *cs = css_cs(css);
2011
2012        mutex_lock(&cpuset_mutex);
2013
2014        if (is_sched_load_balance(cs))
2015                update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
2016
2017        cpuset_dec();
2018        clear_bit(CS_ONLINE, &cs->flags);
2019
2020        mutex_unlock(&cpuset_mutex);
2021}
2022
2023static void cpuset_css_free(struct cgroup_subsys_state *css)
2024{
2025        struct cpuset *cs = css_cs(css);
2026
2027        free_cpumask_var(cs->effective_cpus);
2028        free_cpumask_var(cs->cpus_allowed);
2029        kfree(cs);
2030}
2031
2032static void cpuset_bind(struct cgroup_subsys_state *root_css)
2033{
2034        mutex_lock(&cpuset_mutex);
2035        spin_lock_irq(&callback_lock);
2036
2037        if (cgroup_on_dfl(root_css->cgroup)) {
2038                cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
2039                top_cpuset.mems_allowed = node_possible_map;
2040        } else {
2041                cpumask_copy(top_cpuset.cpus_allowed,
2042                             top_cpuset.effective_cpus);
2043                top_cpuset.mems_allowed = top_cpuset.effective_mems;
2044        }
2045
2046        spin_unlock_irq(&callback_lock);
2047        mutex_unlock(&cpuset_mutex);
2048}
2049
2050struct cgroup_subsys cpuset_cgrp_subsys = {
2051        .css_alloc      = cpuset_css_alloc,
2052        .css_online     = cpuset_css_online,
2053        .css_offline    = cpuset_css_offline,
2054        .css_free       = cpuset_css_free,
2055        .can_attach     = cpuset_can_attach,
2056        .cancel_attach  = cpuset_cancel_attach,
2057        .attach         = cpuset_attach,
2058        .bind           = cpuset_bind,
2059        .legacy_cftypes = files,
2060        .early_init     = 1,
2061};
2062
2063/**
2064 * cpuset_init - initialize cpusets at system boot
2065 *
2066 * Description: Initialize top_cpuset and the cpuset internal file system,
2067 **/
2068
2069int __init cpuset_init(void)
2070{
2071        int err = 0;
2072
2073        if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
2074                BUG();
2075        if (!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL))
2076                BUG();
2077
2078        cpumask_setall(top_cpuset.cpus_allowed);
2079        nodes_setall(top_cpuset.mems_allowed);
2080        cpumask_setall(top_cpuset.effective_cpus);
2081        nodes_setall(top_cpuset.effective_mems);
2082
2083        fmeter_init(&top_cpuset.fmeter);
2084        set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
2085        top_cpuset.relax_domain_level = -1;
2086
2087        err = register_filesystem(&cpuset_fs_type);
2088        if (err < 0)
2089                return err;
2090
2091        if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
2092                BUG();
2093
2094        return 0;
2095}
2096
2097/*
2098 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
2099 * or memory nodes, we need to walk over the cpuset hierarchy,
2100 * removing that CPU or node from all cpusets.  If this removes the
2101 * last CPU or node from a cpuset, then move the tasks in the empty
2102 * cpuset to its next-highest non-empty parent.
2103 */
2104static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
2105{
2106        struct cpuset *parent;
2107
2108        /*
2109         * Find its next-highest non-empty parent, (top cpuset
2110         * has online cpus, so can't be empty).
2111         */
2112        parent = parent_cs(cs);
2113        while (cpumask_empty(parent->cpus_allowed) ||
2114                        nodes_empty(parent->mems_allowed))
2115                parent = parent_cs(parent);
2116
2117        if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
2118                pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
2119                pr_cont_cgroup_name(cs->css.cgroup);
2120                pr_cont("\n");
2121        }
2122}
2123
2124static void
2125hotplug_update_tasks_legacy(struct cpuset *cs,
2126                            struct cpumask *new_cpus, nodemask_t *new_mems,
2127                            bool cpus_updated, bool mems_updated)
2128{
2129        bool is_empty;
2130
2131        spin_lock_irq(&callback_lock);
2132        cpumask_copy(cs->cpus_allowed, new_cpus);
2133        cpumask_copy(cs->effective_cpus, new_cpus);
2134        cs->mems_allowed = *new_mems;
2135        cs->effective_mems = *new_mems;
2136        spin_unlock_irq(&callback_lock);
2137
2138        /*
2139         * Don't call update_tasks_cpumask() if the cpuset becomes empty,
2140         * as the tasks will be migratecd to an ancestor.
2141         */
2142        if (cpus_updated && !cpumask_empty(cs->cpus_allowed))
2143                update_tasks_cpumask(cs);
2144        if (mems_updated && !nodes_empty(cs->mems_allowed))
2145                update_tasks_nodemask(cs);
2146
2147        is_empty = cpumask_empty(cs->cpus_allowed) ||
2148                   nodes_empty(cs->mems_allowed);
2149
2150        mutex_unlock(&cpuset_mutex);
2151
2152        /*
2153         * Move tasks to the nearest ancestor with execution resources,
2154         * This is full cgroup operation which will also call back into
2155         * cpuset. Should be done outside any lock.
2156         */
2157        if (is_empty)
2158                remove_tasks_in_empty_cpuset(cs);
2159
2160        mutex_lock(&cpuset_mutex);
2161}
2162
2163static void
2164hotplug_update_tasks(struct cpuset *cs,
2165                     struct cpumask *new_cpus, nodemask_t *new_mems,
2166                     bool cpus_updated, bool mems_updated)
2167{
2168        if (cpumask_empty(new_cpus))
2169                cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
2170        if (nodes_empty(*new_mems))
2171                *new_mems = parent_cs(cs)->effective_mems;
2172
2173        spin_lock_irq(&callback_lock);
2174        cpumask_copy(cs->effective_cpus, new_cpus);
2175        cs->effective_mems = *new_mems;
2176        spin_unlock_irq(&callback_lock);
2177
2178        if (cpus_updated)
2179                update_tasks_cpumask(cs);
2180        if (mems_updated)
2181                update_tasks_nodemask(cs);
2182}
2183
2184/**
2185 * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
2186 * @cs: cpuset in interest
2187 *
2188 * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
2189 * offline, update @cs accordingly.  If @cs ends up with no CPU or memory,
2190 * all its tasks are moved to the nearest ancestor with both resources.
2191 */
2192static void cpuset_hotplug_update_tasks(struct cpuset *cs)
2193{
2194        static cpumask_t new_cpus;
2195        static nodemask_t new_mems;
2196        bool cpus_updated;
2197        bool mems_updated;
2198retry:
2199        wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
2200
2201        mutex_lock(&cpuset_mutex);
2202
2203        /*
2204         * We have raced with task attaching. We wait until attaching
2205         * is finished, so we won't attach a task to an empty cpuset.
2206         */
2207        if (cs->attach_in_progress) {
2208                mutex_unlock(&cpuset_mutex);
2209                goto retry;
2210        }
2211
2212        cpumask_and(&new_cpus, cs->cpus_allowed, parent_cs(cs)->effective_cpus);
2213        nodes_and(new_mems, cs->mems_allowed, parent_cs(cs)->effective_mems);
2214
2215        cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
2216        mems_updated = !nodes_equal(new_mems, cs->effective_mems);
2217
2218        if (cgroup_on_dfl(cs->css.cgroup))
2219                hotplug_update_tasks(cs, &new_cpus, &new_mems,
2220                                     cpus_updated, mems_updated);
2221        else
2222                hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems,
2223                                            cpus_updated, mems_updated);
2224
2225        mutex_unlock(&cpuset_mutex);
2226}
2227
2228/**
2229 * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
2230 *
2231 * This function is called after either CPU or memory configuration has
2232 * changed and updates cpuset accordingly.  The top_cpuset is always
2233 * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
2234 * order to make cpusets transparent (of no affect) on systems that are
2235 * actively using CPU hotplug but making no active use of cpusets.
2236 *
2237 * Non-root cpusets are only affected by offlining.  If any CPUs or memory
2238 * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
2239 * all descendants.
2240 *
2241 * Note that CPU offlining during suspend is ignored.  We don't modify
2242 * cpusets across suspend/resume cycles at all.
2243 */
2244static void cpuset_hotplug_workfn(struct work_struct *work)
2245{
2246        static cpumask_t new_cpus;
2247        static nodemask_t new_mems;
2248        bool cpus_updated, mems_updated;
2249        bool on_dfl = cgroup_on_dfl(top_cpuset.css.cgroup);
2250
2251        mutex_lock(&cpuset_mutex);
2252
2253        /* fetch the available cpus/mems and find out which changed how */
2254        cpumask_copy(&new_cpus, cpu_active_mask);
2255        new_mems = node_states[N_MEMORY];
2256
2257        cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
2258        mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
2259
2260        /* synchronize cpus_allowed to cpu_active_mask */
2261        if (cpus_updated) {
2262                spin_lock_irq(&callback_lock);
2263                if (!on_dfl)
2264                        cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
2265                cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
2266                spin_unlock_irq(&callback_lock);
2267                /* we don't mess with cpumasks of tasks in top_cpuset */
2268        }
2269
2270        /* synchronize mems_allowed to N_MEMORY */
2271        if (mems_updated) {
2272                spin_lock_irq(&callback_lock);
2273                if (!on_dfl)
2274                        top_cpuset.mems_allowed = new_mems;
2275                top_cpuset.effective_mems = new_mems;
2276                spin_unlock_irq(&callback_lock);
2277                update_tasks_nodemask(&top_cpuset);
2278        }
2279
2280        mutex_unlock(&cpuset_mutex);
2281
2282        /* if cpus or mems changed, we need to propagate to descendants */
2283        if (cpus_updated || mems_updated) {
2284                struct cpuset *cs;
2285                struct cgroup_subsys_state *pos_css;
2286
2287                rcu_read_lock();
2288                cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
2289                        if (cs == &top_cpuset || !css_tryget_online(&cs->css))
2290                                continue;
2291                        rcu_read_unlock();
2292
2293                        cpuset_hotplug_update_tasks(cs);
2294
2295                        rcu_read_lock();
2296                        css_put(&cs->css);
2297                }
2298                rcu_read_unlock();
2299        }
2300
2301        /* rebuild sched domains if cpus_allowed has changed */
2302        if (cpus_updated)
2303                rebuild_sched_domains();
2304}
2305
2306void cpuset_update_active_cpus(bool cpu_online)
2307{
2308        /*
2309         * We're inside cpu hotplug critical region which usually nests
2310         * inside cgroup synchronization.  Bounce actual hotplug processing
2311         * to a work item to avoid reverse locking order.
2312         *
2313         * We still need to do partition_sched_domains() synchronously;
2314         * otherwise, the scheduler will get confused and put tasks to the
2315         * dead CPU.  Fall back to the default single domain.
2316         * cpuset_hotplug_workfn() will rebuild it as necessary.
2317         */
2318        partition_sched_domains(1, NULL, NULL);
2319        schedule_work(&cpuset_hotplug_work);
2320}
2321
2322/*
2323 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
2324 * Call this routine anytime after node_states[N_MEMORY] changes.
2325 * See cpuset_update_active_cpus() for CPU hotplug handling.
2326 */
2327static int cpuset_track_online_nodes(struct notifier_block *self,
2328                                unsigned long action, void *arg)
2329{
2330        schedule_work(&cpuset_hotplug_work);
2331        return NOTIFY_OK;
2332}
2333
2334static struct notifier_block cpuset_track_online_nodes_nb = {
2335        .notifier_call = cpuset_track_online_nodes,
2336        .priority = 10,         /* ??! */
2337};
2338
2339/**
2340 * cpuset_init_smp - initialize cpus_allowed
2341 *
2342 * Description: Finish top cpuset after cpu, node maps are initialized
2343 */
2344void __init cpuset_init_smp(void)
2345{
2346        cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2347        top_cpuset.mems_allowed = node_states[N_MEMORY];
2348        top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
2349
2350        cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
2351        top_cpuset.effective_mems = node_states[N_MEMORY];
2352
2353        register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
2354}
2355
2356/**
2357 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
2358 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2359 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
2360 *
2361 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
2362 * attached to the specified @tsk.  Guaranteed to return some non-empty
2363 * subset of cpu_online_mask, even if this means going outside the
2364 * tasks cpuset.
2365 **/
2366
2367void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
2368{
2369        unsigned long flags;
2370
2371        spin_lock_irqsave(&callback_lock, flags);
2372        rcu_read_lock();
2373        guarantee_online_cpus(task_cs(tsk), pmask);
2374        rcu_read_unlock();
2375        spin_unlock_irqrestore(&callback_lock, flags);
2376}
2377
2378void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
2379{
2380        rcu_read_lock();
2381        do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
2382        rcu_read_unlock();
2383
2384        /*
2385         * We own tsk->cpus_allowed, nobody can change it under us.
2386         *
2387         * But we used cs && cs->cpus_allowed lockless and thus can
2388         * race with cgroup_attach_task() or update_cpumask() and get
2389         * the wrong tsk->cpus_allowed. However, both cases imply the
2390         * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
2391         * which takes task_rq_lock().
2392         *
2393         * If we are called after it dropped the lock we must see all
2394         * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
2395         * set any mask even if it is not right from task_cs() pov,
2396         * the pending set_cpus_allowed_ptr() will fix things.
2397         *
2398         * select_fallback_rq() will fix things ups and set cpu_possible_mask
2399         * if required.
2400         */
2401}
2402
2403void cpuset_init_current_mems_allowed(void)
2404{
2405        nodes_setall(current->mems_allowed);
2406}
2407
2408/**
2409 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
2410 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
2411 *
2412 * Description: Returns the nodemask_t mems_allowed of the cpuset
2413 * attached to the specified @tsk.  Guaranteed to return some non-empty
2414 * subset of node_states[N_MEMORY], even if this means going outside the
2415 * tasks cpuset.
2416 **/
2417
2418nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
2419{
2420        nodemask_t mask;
2421        unsigned long flags;
2422
2423        spin_lock_irqsave(&callback_lock, flags);
2424        rcu_read_lock();
2425        guarantee_online_mems(task_cs(tsk), &mask);
2426        rcu_read_unlock();
2427        spin_unlock_irqrestore(&callback_lock, flags);
2428
2429        return mask;
2430}
2431
2432/**
2433 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
2434 * @nodemask: the nodemask to be checked
2435 *
2436 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
2437 */
2438int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
2439{
2440        return nodes_intersects(*nodemask, current->mems_allowed);
2441}
2442
2443/*
2444 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
2445 * mem_hardwall ancestor to the specified cpuset.  Call holding
2446 * callback_lock.  If no ancestor is mem_exclusive or mem_hardwall
2447 * (an unusual configuration), then returns the root cpuset.
2448 */
2449static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
2450{
2451        while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
2452                cs = parent_cs(cs);
2453        return cs;
2454}
2455
2456/**
2457 * cpuset_node_allowed - Can we allocate on a memory node?
2458 * @node: is this an allowed node?
2459 * @gfp_mask: memory allocation flags
2460 *
2461 * If we're in interrupt, yes, we can always allocate.  If __GFP_THISNODE is
2462 * set, yes, we can always allocate.  If node is in our task's mems_allowed,
2463 * yes.  If it's not a __GFP_HARDWALL request and this node is in the nearest
2464 * hardwalled cpuset ancestor to this task's cpuset, yes.  If the task has been
2465 * OOM killed and has access to memory reserves as specified by the TIF_MEMDIE
2466 * flag, yes.
2467 * Otherwise, no.
2468 *
2469 * The __GFP_THISNODE placement logic is really handled elsewhere,
2470 * by forcibly using a zonelist starting at a specified node, and by
2471 * (in get_page_from_freelist()) refusing to consider the zones for
2472 * any node on the zonelist except the first.  By the time any such
2473 * calls get to this routine, we should just shut up and say 'yes'.
2474 *
2475 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2476 * and do not allow allocations outside the current tasks cpuset
2477 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2478 * GFP_KERNEL allocations are not so marked, so can escape to the
2479 * nearest enclosing hardwalled ancestor cpuset.
2480 *
2481 * Scanning up parent cpusets requires callback_lock.  The
2482 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
2483 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
2484 * current tasks mems_allowed came up empty on the first pass over
2485 * the zonelist.  So only GFP_KERNEL allocations, if all nodes in the
2486 * cpuset are short of memory, might require taking the callback_lock.
2487 *
2488 * The first call here from mm/page_alloc:get_page_from_freelist()
2489 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
2490 * so no allocation on a node outside the cpuset is allowed (unless
2491 * in interrupt, of course).
2492 *
2493 * The second pass through get_page_from_freelist() doesn't even call
2494 * here for GFP_ATOMIC calls.  For those calls, the __alloc_pages()
2495 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
2496 * in alloc_flags.  That logic and the checks below have the combined
2497 * affect that:
2498 *      in_interrupt - any node ok (current task context irrelevant)
2499 *      GFP_ATOMIC   - any node ok
2500 *      TIF_MEMDIE   - any node ok
2501 *      GFP_KERNEL   - any node in enclosing hardwalled cpuset ok
2502 *      GFP_USER     - only nodes in current tasks mems allowed ok.
2503 */
2504int __cpuset_node_allowed(int node, gfp_t gfp_mask)
2505{
2506        struct cpuset *cs;              /* current cpuset ancestors */
2507        int allowed;                    /* is allocation in zone z allowed? */
2508        unsigned long flags;
2509
2510        if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2511                return 1;
2512        if (node_isset(node, current->mems_allowed))
2513                return 1;
2514        /*
2515         * Allow tasks that have access to memory reserves because they have
2516         * been OOM killed to get memory anywhere.
2517         */
2518        if (unlikely(test_thread_flag(TIF_MEMDIE)))
2519                return 1;
2520        if (gfp_mask & __GFP_HARDWALL)  /* If hardwall request, stop here */
2521                return 0;
2522
2523        if (current->flags & PF_EXITING) /* Let dying task have memory */
2524                return 1;
2525
2526        /* Not hardwall and node outside mems_allowed: scan up cpusets */
2527        spin_lock_irqsave(&callback_lock, flags);
2528
2529        rcu_read_lock();
2530        cs = nearest_hardwall_ancestor(task_cs(current));
2531        allowed = node_isset(node, cs->mems_allowed);
2532        rcu_read_unlock();
2533
2534        spin_unlock_irqrestore(&callback_lock, flags);
2535        return allowed;
2536}
2537
2538/**
2539 * cpuset_mem_spread_node() - On which node to begin search for a file page
2540 * cpuset_slab_spread_node() - On which node to begin search for a slab page
2541 *
2542 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
2543 * tasks in a cpuset with is_spread_page or is_spread_slab set),
2544 * and if the memory allocation used cpuset_mem_spread_node()
2545 * to determine on which node to start looking, as it will for
2546 * certain page cache or slab cache pages such as used for file
2547 * system buffers and inode caches, then instead of starting on the
2548 * local node to look for a free page, rather spread the starting
2549 * node around the tasks mems_allowed nodes.
2550 *
2551 * We don't have to worry about the returned node being offline
2552 * because "it can't happen", and even if it did, it would be ok.
2553 *
2554 * The routines calling guarantee_online_mems() are careful to
2555 * only set nodes in task->mems_allowed that are online.  So it
2556 * should not be possible for the following code to return an
2557 * offline node.  But if it did, that would be ok, as this routine
2558 * is not returning the node where the allocation must be, only
2559 * the node where the search should start.  The zonelist passed to
2560 * __alloc_pages() will include all nodes.  If the slab allocator
2561 * is passed an offline node, it will fall back to the local node.
2562 * See kmem_cache_alloc_node().
2563 */
2564
2565static int cpuset_spread_node(int *rotor)
2566{
2567        int node;
2568
2569        node = next_node(*rotor, current->mems_allowed);
2570        if (node == MAX_NUMNODES)
2571                node = first_node(current->mems_allowed);
2572        *rotor = node;
2573        return node;
2574}
2575
2576int cpuset_mem_spread_node(void)
2577{
2578        if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
2579                current->cpuset_mem_spread_rotor =
2580                        node_random(&current->mems_allowed);
2581
2582        return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
2583}
2584
2585int cpuset_slab_spread_node(void)
2586{
2587        if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
2588                current->cpuset_slab_spread_rotor =
2589                        node_random(&current->mems_allowed);
2590
2591        return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
2592}
2593
2594EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
2595
2596/**
2597 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
2598 * @tsk1: pointer to task_struct of some task.
2599 * @tsk2: pointer to task_struct of some other task.
2600 *
2601 * Description: Return true if @tsk1's mems_allowed intersects the
2602 * mems_allowed of @tsk2.  Used by the OOM killer to determine if
2603 * one of the task's memory usage might impact the memory available
2604 * to the other.
2605 **/
2606
2607int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
2608                                   const struct task_struct *tsk2)
2609{
2610        return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2611}
2612
2613#define CPUSET_NODELIST_LEN     (256)
2614
2615/**
2616 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
2617 * @tsk: pointer to task_struct of some task.
2618 *
2619 * Description: Prints @task's name, cpuset name, and cached copy of its
2620 * mems_allowed to the kernel log.
2621 */
2622void cpuset_print_task_mems_allowed(struct task_struct *tsk)
2623{
2624         /* Statically allocated to prevent using excess stack. */
2625        static char cpuset_nodelist[CPUSET_NODELIST_LEN];
2626        static DEFINE_SPINLOCK(cpuset_buffer_lock);
2627        struct cgroup *cgrp;
2628
2629        spin_lock(&cpuset_buffer_lock);
2630        rcu_read_lock();
2631
2632        cgrp = task_cs(tsk)->css.cgroup;
2633        nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
2634                           tsk->mems_allowed);
2635        pr_info("%s cpuset=", tsk->comm);
2636        pr_cont_cgroup_name(cgrp);
2637        pr_cont(" mems_allowed=%s\n", cpuset_nodelist);
2638
2639        rcu_read_unlock();
2640        spin_unlock(&cpuset_buffer_lock);
2641}
2642
2643/*
2644 * Collection of memory_pressure is suppressed unless
2645 * this flag is enabled by writing "1" to the special
2646 * cpuset file 'memory_pressure_enabled' in the root cpuset.
2647 */
2648
2649int cpuset_memory_pressure_enabled __read_mostly;
2650
2651/**
2652 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
2653 *
2654 * Keep a running average of the rate of synchronous (direct)
2655 * page reclaim efforts initiated by tasks in each cpuset.
2656 *
2657 * This represents the rate at which some task in the cpuset
2658 * ran low on memory on all nodes it was allowed to use, and
2659 * had to enter the kernels page reclaim code in an effort to
2660 * create more free memory by tossing clean pages or swapping
2661 * or writing dirty pages.
2662 *
2663 * Display to user space in the per-cpuset read-only file
2664 * "memory_pressure".  Value displayed is an integer
2665 * representing the recent rate of entry into the synchronous
2666 * (direct) page reclaim by any task attached to the cpuset.
2667 **/
2668
2669void __cpuset_memory_pressure_bump(void)
2670{
2671        rcu_read_lock();
2672        fmeter_markevent(&task_cs(current)->fmeter);
2673        rcu_read_unlock();
2674}
2675
2676#ifdef CONFIG_PROC_PID_CPUSET
2677/*
2678 * proc_cpuset_show()
2679 *  - Print tasks cpuset path into seq_file.
2680 *  - Used for /proc/<pid>/cpuset.
2681 *  - No need to task_lock(tsk) on this tsk->cpuset reference, as it
2682 *    doesn't really matter if tsk->cpuset changes after we read it,
2683 *    and we take cpuset_mutex, keeping cpuset_attach() from changing it
2684 *    anyway.
2685 */
2686int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
2687                     struct pid *pid, struct task_struct *tsk)
2688{
2689        char *buf, *p;
2690        struct cgroup_subsys_state *css;
2691        int retval;
2692
2693        retval = -ENOMEM;
2694        buf = kmalloc(PATH_MAX, GFP_KERNEL);
2695        if (!buf)
2696                goto out;
2697
2698        retval = -ENAMETOOLONG;
2699        rcu_read_lock();
2700        css = task_css(tsk, cpuset_cgrp_id);
2701        p = cgroup_path(css->cgroup, buf, PATH_MAX);
2702        rcu_read_unlock();
2703        if (!p)
2704                goto out_free;
2705        seq_puts(m, p);
2706        seq_putc(m, '\n');
2707        retval = 0;
2708out_free:
2709        kfree(buf);
2710out:
2711        return retval;
2712}
2713#endif /* CONFIG_PROC_PID_CPUSET */
2714
2715/* Display task mems_allowed in /proc/<pid>/status file. */
2716void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
2717{
2718        seq_puts(m, "Mems_allowed:\t");
2719        seq_nodemask(m, &task->mems_allowed);
2720        seq_puts(m, "\n");
2721        seq_puts(m, "Mems_allowed_list:\t");
2722        seq_nodemask_list(m, &task->mems_allowed);
2723        seq_puts(m, "\n");
2724}
2725
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.