/*

* kernel/cpuset.c

*

* Processor and Memory placement constraints for sets of tasks.

*

* Copyright (C) 2003 BULL SA.

* Copyright (C) 2004-2007 Silicon Graphics, Inc.

* Copyright (C) 2006 Google, Inc

*

* Portions derived from Patrick Mochel's sysfs code.

* sysfs is Copyright (c) 2001-3 Patrick Mochel

*

* 2003-10-10 Written by Simon Derr.

* 2003-10-22 Updates by Stephen Hemminger.

* 2004 May-July Rework by Paul Jackson.

* 2006 Rework by Paul Menage to use generic cgroups

* 2008 Rework of the scheduler domains and CPU hotplug handling

* by Max Krasnyansky

*

* This file is subject to the terms and conditions of the GNU General Public

* License. See the file COPYING in the main directory of the Linux

* distribution for more details.

*/

#include <linux/cpu.h>

#include <linux/cpumask.h>

#include <linux/cpuset.h>

#include <linux/err.h>

#include <linux/errno.h>

#include <linux/file.h>

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/interrupt.h>

#include <linux/kernel.h>

#include <linux/kmod.h>

#include <linux/list.h>

#include <linux/mempolicy.h>

#include <linux/mm.h>

#include <linux/memory.h>

#include <linux/export.h>

#include <linux/mount.h>

#include <linux/namei.h>

#include <linux/pagemap.h>

#include <linux/proc_fs.h>

#include <linux/rcupdate.h>

#include <linux/sched.h>

#include <linux/sched/mm.h>

#include <linux/sched/task.h>

#include <linux/seq_file.h>

#include <linux/security.h>

#include <linux/slab.h>

#include <linux/spinlock.h>

#include <linux/stat.h>

#include <linux/string.h>

#include <linux/time.h>

#include <linux/time64.h>

#include <linux/backing-dev.h>

#include <linux/sort.h>

#include <linux/oom.h>

#include <linux/uaccess.h>

#include <linux/atomic.h>

#include <linux/mutex.h>

#include <linux/cgroup.h>

#include <linux/wait.h>

DEFINE_STATIC_KEY_FALSE(cpusets_pre_enable_key);

DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key);

/* See "Frequency meter" comments, below. */

struct fmeter {

int cnt; /* unprocessed events count */

int val; /* most recent output value */

time64_t time; /* clock (secs) when val computed */

spinlock_t lock; /* guards read or write of above */

};

struct cpuset {

struct cgroup_subsys_state css;

unsigned long flags; /* "unsigned long" so bitops work */

/*

* On default hierarchy:

*

* The user-configured masks can only be changed by writing to

* cpuset.cpus and cpuset.mems, and won't be limited by the

* parent masks.

*

* The effective masks is the real masks that apply to the tasks

* in the cpuset. They may be changed if the configured masks are

* changed or hotplug happens.

*

* effective_mask == configured_mask & parent's effective_mask,

* and if it ends up empty, it will inherit the parent's mask.

*

*

* On legacy hierachy:

*

* The user-configured masks are always the same with effective masks.

*/

/* user-configured CPUs and Memory Nodes allow to tasks */

cpumask_var_t cpus_allowed;

nodemask_t mems_allowed;

/* effective CPUs and Memory Nodes allow to tasks */

cpumask_var_t effective_cpus;

nodemask_t effective_mems;

/*

* This is old Memory Nodes tasks took on.

*

* - top_cpuset.old_mems_allowed is initialized to mems_allowed.

* - A new cpuset's old_mems_allowed is initialized when some

* task is moved into it.

* - old_mems_allowed is used in cpuset_migrate_mm() when we change

* cpuset.mems_allowed and have tasks' nodemask updated, and

* then old_mems_allowed is updated to mems_allowed.

*/

nodemask_t old_mems_allowed;

struct fmeter fmeter; /* memory_pressure filter */

/*

* Tasks are being attached to this cpuset. Used to prevent

* zeroing cpus/mems_allowed between ->can_attach() and ->attach().

*/

int attach_in_progress;

/* partition number for rebuild_sched_domains() */

int pn;

/* for custom sched domain */

int relax_domain_level;

};

static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)

{

return css ? container_of(css, struct cpuset, css) : NULL;

}

/* Retrieve the cpuset for a task */

static inline struct cpuset *task_cs(struct task_struct *task)

{

return css_cs(task_css(task, cpuset_cgrp_id));

}

static inline struct cpuset *parent_cs(struct cpuset *cs)

{

return css_cs(cs->css.parent);

}

#ifdef CONFIG_NUMA

static inline bool task_has_mempolicy(struct task_struct *task)

{

return task->mempolicy;

}

#else

static inline bool task_has_mempolicy(struct task_struct *task)

{

return false;

}

#endif

/* bits in struct cpuset flags field */

typedef enum {

CS_ONLINE,

CS_CPU_EXCLUSIVE,

CS_MEM_EXCLUSIVE,

CS_MEM_HARDWALL,

CS_MEMORY_MIGRATE,

CS_SCHED_LOAD_BALANCE,

CS_SPREAD_PAGE,

CS_SPREAD_SLAB,

} cpuset_flagbits_t;

/* convenient tests for these bits */

static inline bool is_cpuset_online(struct cpuset *cs)

{

return test_bit(CS_ONLINE, &cs->flags) && !css_is_dying(&cs->css);

}

static inline int is_cpu_exclusive(const struct cpuset *cs)

{

return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);

}

static inline int is_mem_exclusive(const struct cpuset *cs)

{

return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);

}

static inline int is_mem_hardwall(const struct cpuset *cs)

{

return test_bit(CS_MEM_HARDWALL, &cs->flags);

}

static inline int is_sched_load_balance(const struct cpuset *cs)

{

return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);

}

static inline int is_memory_migrate(const struct cpuset *cs)

{

return test_bit(CS_MEMORY_MIGRATE, &cs->flags);

}

static inline int is_spread_page(const struct cpuset *cs)

{

return test_bit(CS_SPREAD_PAGE, &cs->flags);

}

static inline int is_spread_slab(const struct cpuset *cs)

{

return test_bit(CS_SPREAD_SLAB, &cs->flags);

}

static struct cpuset top_cpuset = {

.flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |

(1 << CS_MEM_EXCLUSIVE)),

};

/**

* cpuset_for_each_child - traverse online children of a cpuset

* @child_cs: loop cursor pointing to the current child

* @pos_css: used for iteration

* @parent_cs: target cpuset to walk children of

*

* Walk @child_cs through the online children of @parent_cs. Must be used

* with RCU read locked.

*/

#define cpuset_for_each_child(child_cs, pos_css, parent_cs) \

css_for_each_child((pos_css), &(parent_cs)->css) \

if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))

/**

* cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants

* @des_cs: loop cursor pointing to the current descendant

* @pos_css: used for iteration

* @root_cs: target cpuset to walk ancestor of

*

* Walk @des_cs through the online descendants of @root_cs. Must be used

* with RCU read locked. The caller may modify @pos_css by calling

* css_rightmost_descendant() to skip subtree. @root_cs is included in the

* iteration and the first node to be visited.

*/

#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \

css_for_each_descendant_pre((pos_css), &(root_cs)->css) \

if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))

/*

* There are two global locks guarding cpuset structures - cpuset_mutex and

* callback_lock. We also require taking task_lock() when dereferencing a

* task's cpuset pointer. See "The task_lock() exception", at the end of this

* comment.

*

* A task must hold both locks to modify cpusets. If a task holds

* cpuset_mutex, then it blocks others wanting that mutex, ensuring that it

* is the only task able to also acquire callback_lock and be able to

* modify cpusets. It can perform various checks on the cpuset structure

* first, knowing nothing will change. It can also allocate memory while

* just holding cpuset_mutex. While it is performing these checks, various

* callback routines can briefly acquire callback_lock to query cpusets.

* Once it is ready to make the changes, it takes callback_lock, blocking

* everyone else.

*

* Calls to the kernel memory allocator can not be made while holding

* callback_lock, as that would risk double tripping on callback_lock

* from one of the callbacks into the cpuset code from within

* __alloc_pages().

*

* If a task is only holding callback_lock, then it has read-only

* access to cpusets.

*

* Now, the task_struct fields mems_allowed and mempolicy may be changed

* by other task, we use alloc_lock in the task_struct fields to protect

* them.

*

* The cpuset_common_file_read() handlers only hold callback_lock across

* small pieces of code, such as when reading out possibly multi-word

* cpumasks and nodemasks.

*

* Accessing a task's cpuset should be done in accordance with the

* guidelines for accessing subsystem state in kernel/cgroup.c

*/

static DEFINE_MUTEX(cpuset_mutex);

static DEFINE_SPINLOCK(callback_lock);

static struct workqueue_struct *cpuset_migrate_mm_wq;

/*

* CPU / memory hotplug is handled asynchronously.

*/

static void cpuset_hotplug_workfn(struct work_struct *work);

static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);

static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);

/*

* Cgroup v2 behavior is used when on default hierarchy or the

* cgroup_v2_mode flag is set.

*/

static inline bool is_in_v2_mode(void)

{

return cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||

(cpuset_cgrp_subsys.root->flags & CGRP_ROOT_CPUSET_V2_MODE);

}

/*

* This is ugly, but preserves the userspace API for existing cpuset

* users. If someone tries to mount the "cpuset" filesystem, we

* silently switch it to mount "cgroup" instead

*/

static struct dentry *cpuset_mount(struct file_system_type *fs_type,

int flags, const char *unused_dev_name, void *data)

{

struct file_system_type *cgroup_fs = get_fs_type("cgroup");

struct dentry *ret = ERR_PTR(-ENODEV);

if (cgroup_fs) {

char mountopts[] =

"cpuset,noprefix,"

"release_agent=/sbin/cpuset_release_agent";

ret = cgroup_fs->mount(cgroup_fs, flags,

unused_dev_name, mountopts);

put_filesystem(cgroup_fs);

}

return ret;

}

static struct file_system_type cpuset_fs_type = {

.name = "cpuset",

.mount = cpuset_mount,

};

/*

* Return in pmask the portion of a cpusets's cpus_allowed that

* are online. If none are online, walk up the cpuset hierarchy

* until we find one that does have some online cpus.

*

* One way or another, we guarantee to return some non-empty subset

* of cpu_online_mask.

*

* Call with callback_lock or cpuset_mutex held.

*/

static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)

{

while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) {

cs = parent_cs(cs);

if (unlikely(!cs)) {

/*

* The top cpuset doesn't have any online cpu as a

* consequence of a race between cpuset_hotplug_work

* and cpu hotplug notifier. But we know the top

* cpuset's effective_cpus is on its way to to be

* identical to cpu_online_mask.

*/

cpumask_copy(pmask, cpu_online_mask);

return;

}

}

cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);

}

/*

* Return in *pmask the portion of a cpusets's mems_allowed that

* are online, with memory. If none are online with memory, walk

* up the cpuset hierarchy until we find one that does have some

* online mems. The top cpuset always has some mems online.

*

* One way or another, we guarantee to return some non-empty subset

* of node_states[N_MEMORY].

*

* Call with callback_lock or cpuset_mutex held.

*/

static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)

{

while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))

cs = parent_cs(cs);

nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);

}

/*

* update task's spread flag if cpuset's page/slab spread flag is set

*

* Call with callback_lock or cpuset_mutex held.

*/

static void cpuset_update_task_spread_flag(struct cpuset *cs,

struct task_struct *tsk)

{

if (is_spread_page(cs))

task_set_spread_page(tsk);

else

task_clear_spread_page(tsk);

if (is_spread_slab(cs))

task_set_spread_slab(tsk);

else

task_clear_spread_slab(tsk);

}

/*

* is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?

*

* One cpuset is a subset of another if all its allowed CPUs and

* Memory Nodes are a subset of the other, and its exclusive flags

* are only set if the other's are set. Call holding cpuset_mutex.

*/

static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)

{

return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&

nodes_subset(p->mems_allowed, q->mems_allowed) &&

is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&

is_mem_exclusive(p) <= is_mem_exclusive(q);

}

/**

* alloc_trial_cpuset - allocate a trial cpuset

* @cs: the cpuset that the trial cpuset duplicates

*/

static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)

{

struct cpuset *trial;

trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);

if (!trial)

return NULL;

if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL))

goto free_cs;

if (!alloc_cpumask_var(&trial->effective_cpus, GFP_KERNEL))

goto free_cpus;

cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);

cpumask_copy(trial->effective_cpus, cs->effective_cpus);

return trial;

free_cpus:

free_cpumask_var(trial->cpus_allowed);

free_cs:

kfree(trial);

return NULL;

}

/**

* free_trial_cpuset - free the trial cpuset

* @trial: the trial cpuset to be freed

*/

static void free_trial_cpuset(struct cpuset *trial)

{

free_cpumask_var(trial->effective_cpus);

free_cpumask_var(trial->cpus_allowed);

kfree(trial);

}

/*

* validate_change() - Used to validate that any proposed cpuset change

* follows the structural rules for cpusets.

*

* If we replaced the flag and mask values of the current cpuset

* (cur) with those values in the trial cpuset (trial), would

* our various subset and exclusive rules still be valid? Presumes

* cpuset_mutex held.

*

* 'cur' is the address of an actual, in-use cpuset. Operations

* such as list traversal that depend on the actual address of the

* cpuset in the list must use cur below, not trial.

*

* 'trial' is the address of bulk structure copy of cur, with

* perhaps one or more of the fields cpus_allowed, mems_allowed,

* or flags changed to new, trial values.

*

* Return 0 if valid, -errno if not.

*/

static int validate_change(struct cpuset *cur, struct cpuset *trial)

{

struct cgroup_subsys_state *css;

struct cpuset *c, *par;

int ret;

rcu_read_lock();

/* Each of our child cpusets must be a subset of us */

ret = -EBUSY;

cpuset_for_each_child(c, css, cur)

if (!is_cpuset_subset(c, trial))

goto out;

/* Remaining checks don't apply to root cpuset */

ret = 0;

if (cur == &top_cpuset)

goto out;

par = parent_cs(cur);

/* On legacy hiearchy, we must be a subset of our parent cpuset. */

ret = -EACCES;

if (!is_in_v2_mode() && !is_cpuset_subset(trial, par))

goto out;

/*

* If either I or some sibling (!= me) is exclusive, we can't

* overlap

*/

ret = -EINVAL;

cpuset_for_each_child(c, css, par) {

if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&

c != cur &&

cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))

goto out;

if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&

c != cur &&

nodes_intersects(trial->mems_allowed, c->mems_allowed))

goto out;

}

/*

* Cpusets with tasks - existing or newly being attached - can't

* be changed to have empty cpus_allowed or mems_allowed.

*/

ret = -ENOSPC;

if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) {

if (!cpumask_empty(cur->cpus_allowed) &&

cpumask_empty(trial->cpus_allowed))

goto out;

if (!nodes_empty(cur->mems_allowed) &&

nodes_empty(trial->mems_allowed))

goto out;

}

/*

* We can't shrink if we won't have enough room for SCHED_DEADLINE

* tasks.

*/

ret = -EBUSY;

if (is_cpu_exclusive(cur) &&

!cpuset_cpumask_can_shrink(cur->cpus_allowed,

trial->cpus_allowed))

goto out;

ret = 0;

out:

rcu_read_unlock();

return ret;

}

#ifdef CONFIG_SMP

/*

* Helper routine for generate_sched_domains().

* Do cpusets a, b have overlapping effective cpus_allowed masks?

*/

static int cpusets_overlap(struct cpuset *a, struct cpuset *b)

{

return cpumask_intersects(a->effective_cpus, b->effective_cpus);

}

static void

update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)

{

if (dattr->relax_domain_level < c->relax_domain_level)

dattr->relax_domain_level = c->relax_domain_level;

return;

}

static void update_domain_attr_tree(struct sched_domain_attr *dattr,

struct cpuset *root_cs)

{

struct cpuset *cp;

struct cgroup_subsys_state *pos_css;

rcu_read_lock();

cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {

/* skip the whole subtree if @cp doesn't have any CPU */

if (cpumask_empty(cp->cpus_allowed)) {

pos_css = css_rightmost_descendant(pos_css);

continue;

}

if (is_sched_load_balance(cp))

update_domain_attr(dattr, cp);

}

rcu_read_unlock();

}

/* Must be called with cpuset_mutex held. */

static inline int nr_cpusets(void)

{

/* jump label reference count + the top-level cpuset */

return static_key_count(&cpusets_enabled_key.key) + 1;

}

/*

* generate_sched_domains()

*

* This function builds a partial partition of the systems CPUs

* A 'partial partition' is a set of non-overlapping subsets whose

* union is a subset of that set.

* The output of this function needs to be passed to kernel/sched/core.c

* partition_sched_domains() routine, which will rebuild the scheduler's

* load balancing domains (sched domains) as specified by that partial

* partition.

*

* See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt

* for a background explanation of this.

*

* Does not return errors, on the theory that the callers of this

* routine would rather not worry about failures to rebuild sched

* domains when operating in the severe memory shortage situations

* that could cause allocation failures below.

*

* Must be called with cpuset_mutex held.

*

* The three key local variables below are:

* q - a linked-list queue of cpuset pointers, used to implement a

* top-down scan of all cpusets. This scan loads a pointer

* to each cpuset marked is_sched_load_balance into the

* array 'csa'. For our purposes, rebuilding the schedulers

* sched domains, we can ignore !is_sched_load_balance cpusets.

* csa - (for CpuSet Array) Array of pointers to all the cpusets

* that need to be load balanced, for convenient iterative

* access by the subsequent code that finds the best partition,

* i.e the set of domains (subsets) of CPUs such that the

* cpus_allowed of every cpuset marked is_sched_load_balance

* is a subset of one of these domains, while there are as

* many such domains as possible, each as small as possible.

* doms - Conversion of 'csa' to an array of cpumasks, for passing to

* the kernel/sched/core.c routine partition_sched_domains() in a

* convenient format, that can be easily compared to the prior

* value to determine what partition elements (sched domains)

* were changed (added or removed.)

*

* Finding the best partition (set of domains):

* The triple nested loops below over i, j, k scan over the

* load balanced cpusets (using the array of cpuset pointers in

* csa[]) looking for pairs of cpusets that have overlapping

* cpus_allowed, but which don't have the same 'pn' partition

* number and gives them in the same partition number. It keeps

* looping on the 'restart' label until it can no longer find

* any such pairs.

*

* The union of the cpus_allowed masks from the set of

* all cpusets having the same 'pn' value then form the one

* element of the partition (one sched domain) to be passed to

* partition_sched_domains().

*/

static int generate_sched_domains(cpumask_var_t **domains,

struct sched_domain_attr **attributes)

{

struct cpuset *cp; /* scans q */

struct cpuset **csa; /* array of all cpuset ptrs */

int csn; /* how many cpuset ptrs in csa so far */

int i, j, k; /* indices for partition finding loops */

cpumask_var_t *doms; /* resulting partition; i.e. sched domains */

cpumask_var_t non_isolated_cpus; /* load balanced CPUs */

struct sched_domain_attr *dattr; /* attributes for custom domains */

int ndoms = 0; /* number of sched domains in result */

int nslot; /* next empty doms[] struct cpumask slot */

struct cgroup_subsys_state *pos_css;

doms = NULL;

dattr = NULL;

csa = NULL;

if (!alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL))

goto done;

cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);

/* Special case for the 99% of systems with one, full, sched domain */

if (is_sched_load_balance(&top_cpuset)) {

ndoms = 1;

doms = alloc_sched_domains(ndoms);

if (!doms)

goto done;

dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);

if (dattr) {

*dattr = SD_ATTR_INIT;

update_domain_attr_tree(dattr, &top_cpuset);

}

cpumask_and(doms[0], top_cpuset.effective_cpus,

non_isolated_cpus);

goto done;

}

csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL);

if (!csa)

goto done;

csn = 0;

rcu_read_lock();

cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {

if (cp == &top_cpuset)

continue;

/*

* Continue traversing beyond @cp iff @cp has some CPUs and

* isn't load balancing. The former is obvious. The

* latter: All child cpusets contain a subset of the

* parent's cpus, so just skip them, and then we call

* update_domain_attr_tree() to calc relax_domain_level of

* the corresponding sched domain.

*/

if (!cpumask_empty(cp->cpus_allowed) &&

!(is_sched_load_balance(cp) &&

cpumask_intersects(cp->cpus_allowed, non_isolated_cpus)))

continue;

if (is_sched_load_balance(cp))

csa[csn++] = cp;

/* skip @cp's subtree */

pos_css = css_rightmost_descendant(pos_css);

}

rcu_read_unlock();

for (i = 0; i < csn; i++)

csa[i]->pn = i;

ndoms = csn;

restart:

/* Find the best partition (set of sched domains) */

for (i = 0; i < csn; i++) {

struct cpuset *a = csa[i];

int apn = a->pn;

for (j = 0; j < csn; j++) {

struct cpuset *b = csa[j];

int bpn = b->pn;

if (apn != bpn && cpusets_overlap(a, b)) {

for (k = 0; k < csn; k++) {

struct cpuset *c = csa[k];

if (c->pn == bpn)

c->pn = apn;

}

ndoms--; /* one less element */

goto restart;

}

}

}

/*

* Now we know how many domains to create.

* Convert <csn, csa> to <ndoms, doms> and populate cpu masks.

*/

doms = alloc_sched_domains(ndoms);

if (!doms)

goto done;

/*

* The rest of the code, including the scheduler, can deal with

* dattr==NULL case. No need to abort if alloc fails.

*/

dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);

for (nslot = 0, i = 0; i < csn; i++) {

struct cpuset *a = csa[i];

struct cpumask *dp;

int apn = a->pn;

if (apn < 0) {

/* Skip completed partitions */

continue;

}

dp = doms[nslot];

if (nslot == ndoms) {

static int warnings = 10;

if (warnings) {

pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",

nslot, ndoms, csn, i, apn);

warnings--;

}

continue;

}

cpumask_clear(dp);

if (dattr)

*(dattr + nslot) = SD_ATTR_INIT;

for (j = i; j < csn; j++) {

struct cpuset *b = csa[j];

if (apn == b->pn) {

cpumask_or(dp, dp, b->effective_cpus);

cpumask_and(dp, dp, non_isolated_cpus);

if (dattr)

update_domain_attr_tree(dattr + nslot, b);

/* Done with this partition */

b->pn = -1;

}

}

nslot++;

}

BUG_ON(nslot != ndoms);

done:

free_cpumask_var(non_isolated_cpus);

kfree(csa);

/*

* Fallback to the default domain if kmalloc() failed.

* See comments in partition_sched_domains().

*/

if (doms == NULL)

ndoms = 1;

*domains = doms;

*attributes = dattr;

return ndoms;

}

/*

* Rebuild scheduler domains.

*

* If the flag 'sched_load_balance' of any cpuset with non-empty

* 'cpus' changes, or if the 'cpus' allowed changes in any cpuset

* which has that flag enabled, or if any cpuset with a non-empty

* 'cpus' is removed, then call this routine to rebuild the

* scheduler's dynamic sched domains.

*

* Call with cpuset_mutex held. Takes get_online_cpus().

*/

static void rebuild_sched_domains_locked(void)

{

struct sched_domain_attr *attr;

cpumask_var_t *doms;

int ndoms;

lockdep_assert_held(&cpuset_mutex);

get_online_cpus();

/*

* We have raced with CPU hotplug. Don't do anything to avoid

* passing doms with offlined cpu to partition_sched_domains().

* Anyways, hotplug work item will rebuild sched domains.

*/

if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))

goto out;

/* Generate domain masks and attrs */

ndoms = generate_sched_domains(&doms, &attr);

/* Have scheduler rebuild the domains */

partition_sched_domains(ndoms, doms, attr);

out:

put_online_cpus();

}

#else /* !CONFIG_SMP */

static void rebuild_sched_domains_locked(void)

{

}

#endif /* CONFIG_SMP */

void rebuild_sched_domains(void)

{

mutex_lock(&cpuset_mutex);

rebuild_sched_domains_locked();

mutex_unlock(&cpuset_mutex);

}

/**

* update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.

* @cs: the cpuset in which each task's cpus_allowed mask needs to be changed

*

* Iterate through each task of @cs updating its cpus_allowed to the

* effective cpuset's. As this function is called with cpuset_mutex held,

* cpuset membership stays stable.

*/

static void update_tasks_cpumask(struct cpuset *cs)

{

struct css_task_iter it;

struct task_struct *task;

css_task_iter_start(&cs->css, 0, &it);

while ((task = css_task_iter_next(&it)))

set_cpus_allowed_ptr(task, cs->effective_cpus);

css_task_iter_end(&it);

}

/*

* update_cpumasks_hier - Update effective cpumasks and tasks in the subtree

* @cs: the cpuset to consider

* @new_cpus: temp variable for calculating new effective_cpus

*

* When congifured cpumask is changed, the effective cpumasks of this cpuset

* and all its descendants need to be updated.

*

* On legacy hierachy, effective_cpus will be the same with cpu_allowed.

*

* Called with cpuset_mutex held

*/

static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)

{

struct cpuset *cp;

struct cgroup_subsys_state *pos_css;

bool need_rebuild_sched_domains = false;

rcu_read_lock();

cpuset_for_each_descendant_pre(cp, pos_css, cs) {

struct cpuset *parent = parent_cs(cp);

cpumask_and(new_cpus, cp->cpus_allowed, parent->effective_cpus);

/*

* If it becomes empty, inherit the effective mask of the

* parent, which is guaranteed to have some CPUs.

*/

if (is_in_v2_mode() && cpumask_empty(new_cpus))

cpumask_copy(new_cpus, parent->effective_cpus);

/* Skip the whole subtree if the cpumask remains the same. */

if (cpumask_equal(new_cpus, cp->effective_cpus)) {

pos_css = css_rightmost_descendant(pos_css);

continue;

}

if (!css_tryget_online(&cp->css))

continue;

rcu_read_unlock();

spin_lock_irq(&callback_lock);

cpumask_copy(cp->effective_cpus, new_cpus);

spin_unlock_irq(&callback_lock);

WARN_ON(!is_in_v2_mode() &&

!cpumask_equal(cp->cpus_allowed, cp->effective_cpus));

update_tasks_cpumask(cp);

/*

* If the effective cpumask of any non-empty cpuset is changed,

* we need to rebuild sched domains.

*/

if (!cpumask_empty(cp->cpus_allowed) &&

is_sched_load_balance(cp))

need_rebuild_sched_domains = true;

rcu_read_lock();

css_put(&cp->css);

}

rcu_read_unlock();

if (need_rebuild_sched_domains)

rebuild_sched_domains_locked();

}

/**

* update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it

* @cs: the cpuset to consider

* @trialcs: trial cpuset

* @buf: buffer of cpu numbers written to this cpuset

*/

static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,

const char *buf)

{

int retval;

/* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */

if (cs == &top_cpuset)

return -EACCES;

/*

* An empty cpus_allowed is ok only if the cpuset has no tasks.

* Since cpulist_parse() fails on an empty mask, we special case

* that parsing. The validate_change() call ensures that cpusets

* with tasks have cpus.

*/

if (!*buf) {

cpumask_clear(trialcs->cpus_allowed);

} else {

retval = cpulist_parse(buf, trialcs->cpus_allowed);

if (retval < 0)

return retval;

if (!cpumask_subset(trialcs->cpus_allowed,

top_cpuset.cpus_allowed))

return -EINVAL;

}

/* Nothing to do if the cpus didn't change */

if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))

return 0;

retval = validate_change(cs, trialcs);

if (retval < 0)

return retval;

spin_lock_irq(&callback_lock);

cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);

spin_unlock_irq(&callback_lock);

/* use trialcs->cpus_allowed as a temp variable */