* 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/fs_context.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/deadline.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/sched/isolation.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);
struct fmeter {
int cnt;
int val;
time64_t time;
spinlock_t lock;
};
struct cpuset {
struct cgroup_subsys_state css;
unsigned long flags;
* 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.
*/
cpumask_var_t cpus_allowed;
cpumask_var_t cpus_requested;
nodemask_t mems_allowed;
cpumask_var_t effective_cpus;
nodemask_t effective_mems;
* CPUs allocated to child sub-partitions (default hierarchy only)
* - CPUs granted by the parent = effective_cpus U subparts_cpus
* - effective_cpus and subparts_cpus are mutually exclusive.
*
* effective_cpus contains only onlined CPUs, but subparts_cpus
* may have offlined ones.
*/
cpumask_var_t subparts_cpus;
* 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;
* Tasks are being attached to this cpuset. Used to prevent
* zeroing cpus/mems_allowed between ->can_attach() and ->attach().
*/
int attach_in_progress;
int pn;
int relax_domain_level;
int nr_subparts_cpus;
int partition_root_state;
* Default hierarchy only:
* use_parent_ecpus - set if using parent's effective_cpus
* child_ecpus_count - # of children with use_parent_ecpus set
*/
int use_parent_ecpus;
int child_ecpus_count;
};
* Partition root states:
*
* 0 - not a partition root
*
* 1 - partition root
*
* -1 - invalid partition root
* None of the cpus in cpus_allowed can be put into the parent's
* subparts_cpus. In this case, the cpuset is not a real partition
* root anymore. However, the CPU_EXCLUSIVE bit will still be set
* and the cpuset can be restored back to a partition root if the
* parent cpuset can give more CPUs back to this child cpuset.
*/
#define PRS_DISABLED 0
#define PRS_ENABLED 1
#define PRS_ERROR (-1)
* Temporary cpumasks for working with partitions that are passed among
* functions to avoid memory allocation in inner functions.
*/
struct tmpmasks {
cpumask_var_t addmask, delmask;
cpumask_var_t new_cpus;
};
static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
{
return css ? container_of(css, struct cpuset, css) : NULL;
}
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);
}
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;
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 inline int is_partition_root(const struct cpuset *cs)
{
return cs->partition_root_state > 0;
}
static struct cpuset top_cpuset = {
.flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
.partition_root_state = PRS_ENABLED,
};
* 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);
DEFINE_STATIC_PERCPU_RWSEM(cpuset_rwsem);
void cpuset_read_lock(void)
{
percpu_down_read(&cpuset_rwsem);
}
void cpuset_read_unlock(void)
{
percpu_up_read(&cpuset_rwsem);
}
static DEFINE_SPINLOCK(callback_lock);
static struct workqueue_struct *cpuset_migrate_mm_wq;
* CPU / memory hotplug is handled asynchronously
* for hotplug, synchronously for resume_cpus
*/
static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
* Cgroup v2 behavior is used on the "cpus" and "mems" control files when
* on default hierarchy or when the cpuset_v2_mode flag is set by mounting
* the v1 cpuset cgroup filesystem with the "cpuset_v2_mode" mount option.
* With v2 behavior, "cpus" and "mems" are always what the users have
* requested and won't be changed by hotplug events. Only the effective
* cpus or mems will be affected.
*/
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);
}
* Return in pmask the portion of a task's cpusets's cpus_allowed that
* are online and are capable of running the task. If none are found,
* walk up the cpuset hierarchy until we find one that does have some
* appropriate cpus.
*
* One way or another, we guarantee to return some non-empty subset
* of cpu_active_mask.
*
* Call with callback_lock or cpuset_mutex held.
*/
static void guarantee_online_cpus(struct task_struct *tsk, struct cpumask *pmask)
{
const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
struct cpuset *cs;
if (WARN_ON(!cpumask_and(pmask, possible_mask, cpu_active_mask))) {
cpumask_copy(pmask, cpu_active_mask);
}
rcu_read_lock();
cs = task_cs(tsk);
while (!cpumask_intersects(cs->effective_cpus, pmask)) {
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 be
* identical to cpu_online_mask.
*/
goto out_unlock;
}
}
cpumask_and(pmask, pmask, cs->effective_cpus);
out_unlock:
rcu_read_unlock();
}
* 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_requested, q->cpus_requested) && 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_cpumasks - allocate three cpumasks for cpuset
* @cs: the cpuset that have cpumasks to be allocated.
* @tmp: the tmpmasks structure pointer
* Return: 0 if successful, -ENOMEM otherwise.
*
* Only one of the two input arguments should be non-NULL.
*/
static inline int alloc_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
{
cpumask_var_t *pmask1, *pmask2, *pmask3, *pmask4;
if (cs) {
pmask1 = &cs->cpus_allowed;
pmask2 = &cs->effective_cpus;
pmask3 = &cs->subparts_cpus;
pmask4 = &cs->cpus_requested;
} else {
pmask1 = &tmp->new_cpus;
pmask2 = &tmp->addmask;
pmask3 = &tmp->delmask;
}
if (!zalloc_cpumask_var(pmask1, GFP_KERNEL)) {
return -ENOMEM;
}
if (!zalloc_cpumask_var(pmask2, GFP_KERNEL)) {
goto free_one;
}
if (!zalloc_cpumask_var(pmask3, GFP_KERNEL)) {
goto free_two;
}
if (cs && !zalloc_cpumask_var(pmask4, GFP_KERNEL)) {
goto free_three;
}
if (cs && !zalloc_cpumask_var(&cs->cpus_requested, GFP_KERNEL)) {
goto free_three;
}
return 0;
free_three:
free_cpumask_var(*pmask3);
free_two:
free_cpumask_var(*pmask2);
free_one:
free_cpumask_var(*pmask1);
return -ENOMEM;
}
* free_cpumasks - free cpumasks in a tmpmasks structure
* @cs: the cpuset that have cpumasks to be free.
* @tmp: the tmpmasks structure pointer
*/
static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
{
if (cs) {
free_cpumask_var(cs->cpus_allowed);
free_cpumask_var(cs->cpus_requested);
free_cpumask_var(cs->effective_cpus);
free_cpumask_var(cs->subparts_cpus);
}
if (tmp) {
free_cpumask_var(tmp->new_cpus);
free_cpumask_var(tmp->addmask);
free_cpumask_var(tmp->delmask);
}
}
* 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_cpumasks(trial, NULL)) {
kfree(trial);
return NULL;
}
cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
cpumask_copy(trial->cpus_requested, cs->cpus_requested);
cpumask_copy(trial->effective_cpus, cs->effective_cpus);
return trial;
}
* free_cpuset - free the cpuset
* @cs: the cpuset to be freed
*/
static inline void free_cpuset(struct cpuset *cs)
{
free_cpumasks(cs, NULL);
kfree(cs);
}
* 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();
ret = -EBUSY;
cpuset_for_each_child(c, css, cur) if (!is_cpuset_subset(c, trial)) goto out;
ret = 0;
if (cur == &top_cpuset) {
goto out;
}
par = parent_cs(cur);
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_requested, c->cpus_requested)) {
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) {
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();
}
static inline int nr_cpusets(void)
{
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/admin-guide/cgroup-v1/cpusets.rst
* 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:
* cp - cpuset pointer, used (together with pos_css) to perform a
* top-down scan of all cpusets. 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;
struct cpuset **csa;
int csn;
int i, j, k;
cpumask_var_t *doms;
struct sched_domain_attr *dattr;
int ndoms = 0;
int nslot;
struct cgroup_subsys_state *pos_css;
bool root_load_balance = is_sched_load_balance(&top_cpuset);
doms = NULL;
dattr = NULL;
csa = NULL;
if (root_load_balance && !top_cpuset.nr_subparts_cpus) {
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, housekeeping_cpumask(HK_FLAG_DOMAIN));
goto done;
}
csa = kmalloc_array(nr_cpusets(), sizeof(cp), GFP_KERNEL);
if (!csa) {
goto done;
}
csn = 0;
rcu_read_lock();
if (root_load_balance) {
csa[csn++] = &top_cpuset;
}
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 root is load-balancing, we can skip @cp if it
* is a subset of the root's effective_cpus.
*/
if (!cpumask_empty(cp->cpus_allowed) &&
!(is_sched_load_balance(cp) &&
cpumask_intersects(cp->cpus_allowed, housekeeping_cpumask(HK_FLAG_DOMAIN)))) {
continue;
}
if (root_load_balance && cpumask_subset(cp->cpus_allowed, top_cpuset.effective_cpus)) {
continue;
}
if (is_sched_load_balance(cp) && !cpumask_empty(cp->effective_cpus)) {
csa[csn++] = cp;
}
if (!is_partition_root(cp)) {
pos_css = css_rightmost_descendant(pos_css);
}
}
rcu_read_unlock();
for (i = 0; i < csn; i++) {
csa[i]->pn = i;
}
ndoms = csn;
restart:
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--;
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_array(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) {
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, housekeeping_cpumask(HK_FLAG_DOMAIN));
if (dattr) {
update_domain_attr_tree(dattr + nslot, b);
}
b->pn = -1;
}
}
nslot++;
}
BUG_ON(nslot != ndoms);
done:
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;
}
static void update_tasks_root_domain(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))) {
dl_add_task_root_domain(task);
}
css_task_iter_end(&it);
}
static void rebuild_root_domains(void)
{
struct cpuset *cs = NULL;
struct cgroup_subsys_state *pos_css;
lockdep_assert_held(&cpuset_mutex);
lockdep_assert_cpus_held();
lockdep_assert_held(&sched_domains_mutex);
rcu_read_lock();
* Clear default root domain DL accounting, it will be computed again
* if a task belongs to it.
*/
dl_clear_root_domain(&def_root_domain);
cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
if (cpumask_empty(cs->effective_cpus)) {
pos_css = css_rightmost_descendant(pos_css);
continue;
}
css_get(&cs->css);
rcu_read_unlock();
update_tasks_root_domain(cs);
rcu_read_lock();
css_put(&cs->css);
}
rcu_read_unlock();
}
static void partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
struct sched_domain_attr *dattr_new)
{
mutex_lock(&sched_domains_mutex);
partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
rebuild_root_domains();
mutex_unlock(&sched_domains_mutex);
}
* 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 cgroup_subsys_state *pos_css;
struct sched_domain_attr *attr;
cpumask_var_t *doms;
struct cpuset *cs;
int ndoms;
lockdep_assert_held(&cpuset_mutex);
* If we have raced with CPU hotplug, return early to avoid
* passing doms with offlined cpu to partition_sched_domains().
* Anyways, cpuset_hotplug_workfn() will rebuild sched domains.
*
* With no CPUs in any subpartitions, top_cpuset's effective CPUs
* should be the same as the active CPUs, so checking only top_cpuset
* is enough to detect racing CPU offlines.
*/
if (!top_cpuset.nr_subparts_cpus && !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) {
return;
}
* With subpartition CPUs, however, the effective CPUs of a partition
* root should be only a subset of the active CPUs. Since a CPU in any
* partition root could be offlined, all must be checked.
*/
if (top_cpuset.nr_subparts_cpus) {
rcu_read_lock();
cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
if (!is_partition_root(cs)) {
pos_css = css_rightmost_descendant(pos_css);
continue;
}
if (!cpumask_subset(cs->effective_cpus, cpu_active_mask)) {
rcu_read_unlock();
return;
}
}
rcu_read_unlock();
}
ndoms = generate_sched_domains(&doms, &attr);
partition_and_rebuild_sched_domains(ndoms, doms, attr);
}
#else
static void rebuild_sched_domains_locked(void)
{
}
#endif
void rebuild_sched_domains(void)
{
get_online_cpus();
mutex_lock(&cpuset_mutex);
rebuild_sched_domains_locked();
mutex_unlock(&cpuset_mutex);
put_online_cpus();
}
static int update_cpus_allowed(struct cpuset *cs, struct task_struct *p, const struct cpumask *new_mask)
{
return set_cpus_allowed_ptr(p, new_mask);
}
* 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))) {
update_cpus_allowed(cs, task, cs->effective_cpus);
}
css_task_iter_end(&it);
}
* compute_effective_cpumask - Compute the effective cpumask of the cpuset
* @new_cpus: the temp variable for the new effective_cpus mask
* @cs: the cpuset the need to recompute the new effective_cpus mask
* @parent: the parent cpuset
*
* If the parent has subpartition CPUs, include them in the list of
* allowable CPUs in computing the new effective_cpus mask. Since offlined
* CPUs are not removed from subparts_cpus, we have to use cpu_active_mask
* to mask those out.
*/
static void compute_effective_cpumask(struct cpumask *new_cpus, struct cpuset *cs, struct cpuset *parent)
{
if (parent->nr_subparts_cpus) {
cpumask_or(new_cpus, parent->effective_cpus, parent->subparts_cpus);
cpumask_and(new_cpus, new_cpus, cs->cpus_requested);
cpumask_and(new_cpus, new_cpus, cpu_active_mask);
} else {
cpumask_and(new_cpus, cs->cpus_requested, parent_cs(cs)->effective_cpus);
}
}
* Commands for update_parent_subparts_cpumask
*/
enum subparts_cmd {
partcmd_enable,
partcmd_disable,
partcmd_update,
};
* update_parent_subparts_cpumask - update subparts_cpus mask of parent cpuset
* @cpuset: The cpuset that requests change in partition root state
* @cmd: Partition root state change command
* @newmask: Optional new cpumask for partcmd_update
* @tmp: Temporary addmask and delmask
* Return: 0, 1 or an error code
*
* For partcmd_enable, the cpuset is being transformed from a non-partition
* root to a partition root. The cpus_allowed mask of the given cpuset will
* be put into parent's subparts_cpus and taken away from parent's
* effective_cpus. The function will return 0 if all the CPUs listed in
* cpus_allowed can be granted or an error code will be returned.
*
* For partcmd_disable, the cpuset is being transofrmed from a partition
* root back to a non-partition root. Any CPUs in cpus_allowed that are in
* parent's subparts_cpus will be taken away from that cpumask and put back
* into parent's effective_cpus. 0 should always be returned.
*
* For partcmd_update, if the optional newmask is specified, the cpu
* list is to be changed from cpus_allowed to newmask. Otherwise,
* cpus_allowed is assumed to remain the same. The cpuset should either
* be a partition root or an invalid partition root. The partition root
* state may change if newmask is NULL and none of the requested CPUs can
* be granted by the parent. The function will return 1 if changes to
* parent's subparts_cpus and effective_cpus happen or 0 otherwise.
* Error code should only be returned when newmask is non-NULL.
*
* The partcmd_enable and partcmd_disable commands are used by
* update_prstate(). The partcmd_update command is used by
* update_cpumasks_hier() with newmask NULL and update_cpumask() with
* newmask set.
*
* The checking is more strict when enabling partition root than the
* other two commands.
*
* Because of the implicit cpu exclusive nature of a partition root,
* cpumask changes that violates the cpu exclusivity rule will not be
* permitted when checked by validate_change(). The validate_change()
* function will also prevent any changes to the cpu list if it is not
* a superset of children's cpu lists.
*/
static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, struct cpumask *newmask, struct tmpmasks *tmp)
{
struct cpuset *parent = parent_cs(cpuset);
int adding;
int deleting;
int new_prs;
bool part_error = false;
lockdep_assert_held(&cpuset_mutex);
* The parent must be a partition root.
* The new cpumask, if present, or the current cpus_allowed must
* not be empty.
*/
if (!is_partition_root(parent) || (newmask && cpumask_empty(newmask)) ||
(!newmask && cpumask_empty(cpuset->cpus_allowed))) {
return -EINVAL;
}
* Enabling/disabling partition root is not allowed if there are
* online children.
*/
if ((cmd != partcmd_update) && css_has_online_children(&cpuset->css)) {
return -EBUSY;
}
* Enabling partition root is not allowed if not all the CPUs
* can be granted from parent's effective_cpus or at least one
* CPU will be left after that.
*/
if ((cmd == partcmd_enable) && (!cpumask_subset(cpuset->cpus_allowed, parent->effective_cpus) ||
cpumask_equal(cpuset->cpus_allowed, parent->effective_cpus))) {
return -EINVAL;
}
* A cpumask update cannot make parent's effective_cpus become empty.
*/
adding = deleting = false;
new_prs = cpuset->partition_root_state;
if (cmd == partcmd_enable) {
cpumask_copy(tmp->addmask, cpuset->cpus_allowed);
adding = true;
} else if (cmd == partcmd_disable) {
deleting = cpumask_and(tmp->delmask, cpuset->cpus_allowed, parent->subparts_cpus);
} else if (newmask) {
* partcmd_update with newmask:
*
* delmask = cpus_allowed & ~newmask & parent->subparts_cpus
* addmask = newmask & parent->effective_cpus
* & ~parent->subparts_cpus
*/
cpumask_andnot(tmp->delmask, cpuset->cpus_allowed, newmask);
deleting = cpumask_and(tmp->delmask, tmp->delmask, parent->subparts_cpus);
cpumask_and(tmp->addmask, newmask, parent->effective_cpus);
adding = cpumask_andnot(tmp->addmask, tmp->addmask, parent->subparts_cpus);
* Return error if the new effective_cpus could become empty.
*/
if (adding && cpumask_equal(parent->effective_cpus, tmp->addmask)) {
if (!deleting) {
return -EINVAL;
}
* As some of the CPUs in subparts_cpus might have
* been offlined, we need to compute the real delmask
* to confirm that.
*/
if (!cpumask_and(tmp->addmask, tmp->delmask, cpu_active_mask)) {
return -EINVAL;
}
cpumask_copy(tmp->addmask, parent->effective_cpus);
}
} else {
* partcmd_update w/o newmask:
*
* addmask = cpus_allowed & parent->effective_cpus
*
* Note that parent's subparts_cpus may have been
* pre-shrunk in case there is a change in the cpu list.
* So no deletion is needed.
*/
adding = cpumask_and(tmp->addmask, cpuset->cpus_allowed, parent->effective_cpus);
part_error = cpumask_equal(tmp->addmask, parent->effective_cpus);
}
if (cmd == partcmd_update) {
int prev_prs = cpuset->partition_root_state;
* Check for possible transition between PRS_ENABLED
* and PRS_ERROR.
*/
switch (cpuset->partition_root_state) {
case PRS_ENABLED:
if (part_error) {
new_prs = PRS_ERROR;
}
break;
case PRS_ERROR:
if (!part_error) {
new_prs = PRS_ENABLED;
}
break;
default:
break;
}
* Set part_error if previously in invalid state.
*/
part_error = (prev_prs == PRS_ERROR);
}
if (!part_error && (new_prs == PRS_ERROR)) {
return 0;
}
if (new_prs == PRS_ERROR) {
* Remove all its cpus from parent's subparts_cpus.
*/
adding = false;
deleting = cpumask_and(tmp->delmask, cpuset->cpus_allowed, parent->subparts_cpus);
}
if (!adding && !deleting && (new_prs == cpuset->partition_root_state)) {
return 0;
}
* Change the parent's subparts_cpus.
* Newly added CPUs will be removed from effective_cpus and
* newly deleted ones will be added back to effective_cpus.
*/
spin_lock_irq(&callback_lock);
if (adding) {
cpumask_or(parent->subparts_cpus, parent->subparts_cpus, tmp->addmask);
cpumask_andnot(parent->effective_cpus, parent->effective_cpus, tmp->addmask);
}
if (deleting) {
cpumask_andnot(parent->subparts_cpus, parent->subparts_cpus, tmp->delmask);
* Some of the CPUs in subparts_cpus might have been offlined.
*/
cpumask_and(tmp->delmask, tmp->delmask, cpu_active_mask);
cpumask_or(parent->effective_cpus, parent->effective_cpus, tmp->delmask);
}
parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus);
if (cpuset->partition_root_state != new_prs) {
cpuset->partition_root_state = new_prs;
}
spin_unlock_irq(&callback_lock);
return cmd == partcmd_update;
}
* update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
* @cs: the cpuset to consider
* @tmp: temp variables for calculating effective_cpus & partition setup
*
* 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 tmpmasks *tmp)
{
struct cpuset *cp;
struct cgroup_subsys_state *pos_css;
bool need_rebuild_sched_domains = false;
int new_prs;
rcu_read_lock();
cpuset_for_each_descendant_pre(cp, pos_css, cs) {
struct cpuset *parent = parent_cs(cp);
compute_effective_cpumask(tmp->new_cpus, cp, parent);
* 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(tmp->new_cpus)) {
cpumask_copy(tmp->new_cpus, parent->effective_cpus);
if (!cp->use_parent_ecpus) {
cp->use_parent_ecpus = true;
parent->child_ecpus_count++;
}
} else if (cp->use_parent_ecpus) {
cp->use_parent_ecpus = false;
WARN_ON_ONCE(!parent->child_ecpus_count);
parent->child_ecpus_count--;
}
* Skip the whole subtree if the cpumask remains the same
* and has no partition root state.
*/
if (!cp->partition_root_state && cpumask_equal(tmp->new_cpus, cp->effective_cpus)) {
pos_css = css_rightmost_descendant(pos_css);
continue;
}
* update_parent_subparts_cpumask() should have been called
* for cs already in update_cpumask(). We should also call
* update_tasks_cpumask() again for tasks in the parent
* cpuset if the parent's subparts_cpus changes.
*/
new_prs = cp->partition_root_state;
if ((cp != cs) && new_prs) {
switch (parent->partition_root_state) {
case PRS_DISABLED:
* If parent is not a partition root or an
* invalid partition root, clear its state
* and its CS_CPU_EXCLUSIVE flag.
*/
WARN_ON_ONCE(cp->partition_root_state != PRS_ERROR);
new_prs = PRS_DISABLED;
* clear_bit() is an atomic operation and
* readers aren't interested in the state
* of CS_CPU_EXCLUSIVE anyway. So we can
* just update the flag without holding
* the callback_lock.
*/
clear_bit(CS_CPU_EXCLUSIVE, &cp->flags);
break;
case PRS_ENABLED:
if (update_parent_subparts_cpumask(cp, partcmd_update, NULL, tmp)) {
update_tasks_cpumask(parent);
}
break;
case PRS_ERROR:
* When parent is invalid, it has to be too.
*/
new_prs = PRS_ERROR;
break;
}
}
if (!css_tryget_online(&cp->css)) {
continue;
}
rcu_read_unlock();
spin_lock_irq(&callback_lock);
cpumask_copy(cp->effective_cpus, tmp->new_cpus);
if (cp->nr_subparts_cpus && (new_prs != PRS_ENABLED)) {
cp->nr_subparts_cpus = 0;
cpumask_clear(cp->subparts_cpus);
} else if (cp->nr_subparts_cpus) {
* Make sure that effective_cpus & subparts_cpus
* are mutually exclusive.
*
* In the unlikely event that effective_cpus
* becomes empty. we clear cp->nr_subparts_cpus and
* let its child partition roots to compete for
* CPUs again.
*/
cpumask_andnot(cp->effective_cpus, cp->effective_cpus, cp->subparts_cpus);
if (cpumask_empty(cp->effective_cpus)) {
cpumask_copy(cp->effective_cpus, tmp->new_cpus);
cpumask_clear(cp->subparts_cpus);
cp->nr_subparts_cpus = 0;
} else if (!cpumask_subset(cp->subparts_cpus, tmp->new_cpus)) {
cpumask_andnot(cp->subparts_cpus, cp->subparts_cpus, tmp->new_cpus);
cp->nr_subparts_cpus = cpumask_weight(cp->subparts_cpus);
}
}
if (new_prs != cp->partition_root_state) {
cp->partition_root_state = new_prs;
}
spin_unlock_irq(&callback_lock);
WARN_ON(!is_in_v2_mode() && !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
update_tasks_cpumask(cp);
* On legacy hierarchy, if the effective cpumask of any non-
* empty cpuset is changed, we need to rebuild sched domains.
* On default hierarchy, the cpuset needs to be a partition
* root as well.
*/
if (!cpumask_empty(cp->cpus_allowed) && is_sched_load_balance(cp) &&
(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) || is_partition_root(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_sibling_cpumasks - Update siblings cpumasks
* @parent: Parent cpuset
* @cs: Current cpuset
* @tmp: Temp variables
*/
static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs, struct tmpmasks *tmp)
{
struct cpuset *sibling;
struct cgroup_subsys_state *pos_css;
percpu_rwsem_assert_held(&cpuset_rwsem);
* Check all its siblings and call update_cpumasks_hier()
* if their use_parent_ecpus flag is set in order for them
* to use the right effective_cpus value.
*/
rcu_read_lock();
cpuset_for_each_child(sibling, pos_css, parent) {
if (sibling == cs) {
continue;
}
if (!sibling->use_parent_ecpus) {
continue;
}
if (!css_tryget_online(&sibling->css)) {
continue;
}
rcu_read_unlock();
update_cpumasks_hier(sibling, tmp);
rcu_read_lock();
css_put(&sibling->css);
}
rcu_read_unlock();
}
* 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;
struct tmpmasks tmp;
if (cs == &top_cpuset) {
return -EACCES;
}
* An empty cpus_requested 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_requested);
} else {
retval = cpulist_parse(buf, trialcs->cpus_requested);
if (retval < 0) {
return retval;
}
}
if (!cpumask_subset(trialcs->cpus_requested, cpu_present_mask)) {
return -EINVAL;
}
cpumask_and(trialcs->cpus_allowed, trialcs->cpus_requested, cpu_active_mask);
if (cpumask_equal(cs->cpus_requested, trialcs->cpus_requested)) {
return 0;
}
retval = validate_change(cs, trialcs);
if (retval < 0) {
return retval;
}
#ifdef CONFIG_CPUMASK_OFFSTACK
* Use the cpumasks in trialcs for tmpmasks when they are pointers
* to allocated cpumasks.
*/
tmp.addmask = trialcs->subparts_cpus;
tmp.delmask = trialcs->effective_cpus;
tmp.new_cpus = trialcs->cpus_allowed;
#endif
if (cs->partition_root_state) {
if (cpumask_empty(trialcs->cpus_allowed)) {
return -EINVAL;
}
if (update_parent_subparts_cpumask(cs, partcmd_update, trialcs->cpus_allowed, &tmp) < 0) {
return -EINVAL;
}
}
spin_lock_irq(&callback_lock);
cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
cpumask_copy(cs->cpus_requested, trialcs->cpus_requested);
* Make sure that subparts_cpus is a subset of cpus_allowed.
*/
if (cs->nr_subparts_cpus) {
cpumask_and(cs->subparts_cpus, cs->subparts_cpus, cs->cpus_allowed);
cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus);
}
spin_unlock_irq(&callback_lock);
update_cpumasks_hier(cs, &tmp);
if (cs->partition_root_state) {
struct cpuset *parent = parent_cs(cs);
* For partition root, update the cpumasks of sibling
* cpusets if they use parent's effective_cpus.
*/
if (parent->child_ecpus_count) {
update_sibling_cpumasks(parent, cs, &tmp);
}
}
return 0;
}
* Migrate memory region from one set of nodes to another. This is
* performed asynchronously as it can be called from process migration path
* holding locks involved in process management. All mm migrations are
* performed in the queued order and can be waited for by flushing
* cpuset_migrate_mm_wq.
*/
struct cpuset_migrate_mm_work {
struct work_struct work;
struct mm_struct *mm;
nodemask_t from;
nodemask_t to;
};
static void cpuset_migrate_mm_workfn(struct work_struct *work)
{
struct cpuset_migrate_mm_work *mwork = container_of(work, struct cpuset_migrate_mm_work, work);
do_migrate_pages(mwork->mm, &mwork->from, &mwork->to, MPOL_MF_MOVE_ALL);
mmput(mwork->mm);
kfree(mwork);
}
static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, const nodemask_t *to)
{
struct cpuset_migrate_mm_work *mwork;
mwork = kzalloc(sizeof(*mwork), GFP_KERNEL);
if (mwork) {
mwork->mm = mm;
mwork->from = *from;
mwork->to = *to;
INIT_WORK(&mwork->work, cpuset_migrate_mm_workfn);
queue_work(cpuset_migrate_mm_wq, &mwork->work);
} else {
mmput(mm);
}
}
static void cpuset_post_attach(void)
{
flush_workqueue(cpuset_migrate_mm_wq);
}
* cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
* @tsk: the task to change
* @newmems: new nodes that the task will be set
*
* We use the mems_allowed_seq seqlock to safely update both tsk->mems_allowed
* and rebind an eventual tasks' mempolicy. If the task is allocating in
* parallel, it might temporarily see an empty intersection, which results in
* a seqlock check and retry before OOM or allocation failure.
*/
static void cpuset_change_task_nodemask(struct task_struct *tsk, nodemask_t *newmems)
{
task_lock(tsk);
local_irq_disable();
write_seqcount_begin(&tsk->mems_allowed_seq);
nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
mpol_rebind_task(tsk, newmems);
tsk->mems_allowed = *newmems;
write_seqcount_end(&tsk->mems_allowed_seq);
local_irq_enable();
task_unlock(tsk);
}
static void *cpuset_being_rebound;
* update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
* @cs: the cpuset in which each task's mems_allowed mask needs to be changed
*
* Iterate through each task of @cs updating its mems_allowed to the
* effective cpuset's. As this function is called with cpuset_mutex held,
* cpuset membership stays stable.
*/
static void update_tasks_nodemask(struct cpuset *cs)
{
static nodemask_t newmems;
struct css_task_iter it;
struct task_struct *task;
cpuset_being_rebound = cs;
guarantee_online_mems(cs, &newmems);
* The mpol_rebind_mm() call takes mmap_lock, which we couldn't
* take while holding tasklist_lock. Forks can happen - the
* mpol_dup() cpuset_being_rebound check will catch such forks,
* and rebind their vma mempolicies too. Because we still hold
* the global cpuset_mutex, we know that no other rebind effort
* will be contending for the global variable cpuset_being_rebound.
* It's ok if we rebind the same mm twice; mpol_rebind_mm()
* is idempotent. Also migrate pages in each mm to new nodes.
*/
css_task_iter_start(&cs->css, 0, &it);
while ((task = css_task_iter_next(&it))) {
struct mm_struct *mm;
bool migrate;
cpuset_change_task_nodemask(task, &newmems);
mm = get_task_mm(task);
if (!mm) {
continue;
}
migrate = is_memory_migrate(cs);
mpol_rebind_mm(mm, &cs->mems_allowed);
if (migrate) {
cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
} else {
mmput(mm);
}
}
css_task_iter_end(&it);
* All the tasks' nodemasks have been updated, update
* cs->old_mems_allowed.
*/
cs->old_mems_allowed = newmems;
cpuset_being_rebound = NULL;
}
* update_nodemasks_hier - Update effective nodemasks and tasks in the subtree
* @cs: the cpuset to consider
* @new_mems: a temp variable for calculating new effective_mems
*
* When configured nodemask is changed, the effective nodemasks of this cpuset
* and all its descendants need to be updated.
*
* On legacy hiearchy, effective_mems will be the same with mems_allowed.
*
* Called with cpuset_mutex held
*/
static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
{
struct cpuset *cp;
struct cgroup_subsys_state *pos_css;
rcu_read_lock();
cpuset_for_each_descendant_pre(cp, pos_css, cs) {
struct cpuset *parent = parent_cs(cp);
nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
* If it becomes empty, inherit the effective mask of the
* parent, which is guaranteed to have some MEMs.
*/
if (is_in_v2_mode() && nodes_empty(*new_mems)) {
*new_mems = parent->effective_mems;
}
if (nodes_equal(*new_mems, cp->effective_mems)) {
pos_css = css_rightmost_descendant(pos_css);
continue;
}
if (!css_tryget_online(&cp->css)) {
continue;
}
rcu_read_unlock();
spin_lock_irq(&callback_lock);
cp->effective_mems = *new_mems;
spin_unlock_irq(&callback_lock);
WARN_ON(!is_in_v2_mode() && !nodes_equal(cp->mems_allowed, cp->effective_mems));
update_tasks_nodemask(cp);
rcu_read_lock();
css_put(&cp->css);
}
rcu_read_unlock();
}
* Handle user request to change the 'mems' memory placement
* of a cpuset. Needs to validate the request, update the
* cpusets mems_allowed, and for each task in the cpuset,
* update mems_allowed and rebind task's mempolicy and any vma
* mempolicies and if the cpuset is marked 'memory_migrate',
* migrate the tasks pages to the new memory.
*
* Call with cpuset_mutex held. May take callback_lock during call.
* Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
* lock each such tasks mm->mmap_lock, scan its vma's and rebind
* their mempolicies to the cpusets new mems_allowed.
*/
static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, const char *buf)
{
int retval;
* top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
* it's read-only
*/
if (cs == &top_cpuset) {
retval = -EACCES;
goto done;
}
* An empty mems_allowed is ok iff there are no tasks in the cpuset.
* Since nodelist_parse() fails on an empty mask, we special case
* that parsing. The validate_change() call ensures that cpusets
* with tasks have memory.
*/
if (!*buf) {
nodes_clear(trialcs->mems_allowed);
} else {
retval = nodelist_parse(buf, trialcs->mems_allowed);
if (retval < 0) {
goto done;
}
if (!nodes_subset(trialcs->mems_allowed, top_cpuset.mems_allowed)) {
retval = -EINVAL;
goto done;
}
}
if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
retval = 0;
goto done;
}
retval = validate_change(cs, trialcs);
if (retval < 0) {
goto done;
}
spin_lock_irq(&callback_lock);
cs->mems_allowed = trialcs->mems_allowed;
spin_unlock_irq(&callback_lock);
update_nodemasks_hier(cs, &trialcs->mems_allowed);
done:
return retval;
}
bool current_cpuset_is_being_rebound(void)
{
bool ret;
rcu_read_lock();
ret = task_cs(current) == cpuset_being_rebound;
rcu_read_unlock();
return ret;
}
static int update_relax_domain_level(struct cpuset *cs, s64 val)
{
#ifdef CONFIG_SMP
if (val < -1 || val >= sched_domain_level_max) {
return -EINVAL;
}
#endif
if (val != cs->relax_domain_level) {
cs->relax_domain_level = val;
if (!cpumask_empty(cs->cpus_allowed) && is_sched_load_balance(cs)) {
rebuild_sched_domains_locked();
}
}
return 0;
}
* update_tasks_flags - update the spread flags of tasks in the cpuset.
* @cs: the cpuset in which each task's spread flags needs to be changed
*
* Iterate through each task of @cs updating its spread flags. As this
* function is called with cpuset_mutex held, cpuset membership stays
* stable.
*/
static void update_tasks_flags(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))) {
cpuset_update_task_spread_flag(cs, task);
}
css_task_iter_end(&it);
}
* update_flag - read a 0 or a 1 in a file and update associated flag
* bit: the bit to update (see cpuset_flagbits_t)
* cs: the cpuset to update
* turning_on: whether the flag is being set or cleared
*
* Call with cpuset_mutex held.
*/
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, int turning_on)
{
struct cpuset *trialcs;
int balance_flag_changed;
int spread_flag_changed;
int err;
trialcs = alloc_trial_cpuset(cs);
if (!trialcs) {
return -ENOMEM;
}
if (turning_on) {
set_bit(bit, &trialcs->flags);
} else {
clear_bit(bit, &trialcs->flags);
}
err = validate_change(cs, trialcs);
if (err < 0) {
goto out;
}
balance_flag_changed = (is_sched_load_balance(cs) != is_sched_load_balance(trialcs));
spread_flag_changed =
((is_spread_slab(cs) != is_spread_slab(trialcs)) || (is_spread_page(cs) != is_spread_page(trialcs)));
spin_lock_irq(&callback_lock);
cs->flags = trialcs->flags;
spin_unlock_irq(&callback_lock);
if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed) {
rebuild_sched_domains_locked();
}
if (spread_flag_changed) {
update_tasks_flags(cs);
}
out:
free_cpuset(trialcs);
return err;
}
* update_prstate - update partititon_root_state
* cs: the cpuset to update
* new_prs: new partition root state
*
* Call with cpuset_mutex held.
*/
static int update_prstate(struct cpuset *cs, int new_prs)
{
int err, old_prs = cs->partition_root_state;
struct cpuset *parent = parent_cs(cs);
struct tmpmasks tmpmask;
if (old_prs == new_prs) {
return 0;
}
* Cannot force a partial or invalid partition root to a full
* partition root.
*/
if (new_prs && (old_prs == PRS_ERROR)) {
return -EINVAL;
}
if (alloc_cpumasks(NULL, &tmpmask)) {
return -ENOMEM;
}
err = -EINVAL;
if (!old_prs) {
* Turning on partition root requires setting the
* CS_CPU_EXCLUSIVE bit implicitly as well and cpus_allowed
* cannot be NULL.
*/
if (cpumask_empty(cs->cpus_allowed)) {
goto out;
}
err = update_flag(CS_CPU_EXCLUSIVE, cs, 1);
if (err) {
goto out;
}
err = update_parent_subparts_cpumask(cs, partcmd_enable, NULL, &tmpmask);
if (err) {
update_flag(CS_CPU_EXCLUSIVE, cs, 0);
goto out;
}
} else {
* Turning off partition root will clear the
* CS_CPU_EXCLUSIVE bit.
*/
if (old_prs == PRS_ERROR) {
update_flag(CS_CPU_EXCLUSIVE, cs, 0);
err = 0;
goto out;
}
err = update_parent_subparts_cpumask(cs, partcmd_disable, NULL, &tmpmask);
if (err) {
goto out;
}
update_flag(CS_CPU_EXCLUSIVE, cs, 0);
}
* Update cpumask of parent's tasks except when it is the top
* cpuset as some system daemons cannot be mapped to other CPUs.
*/
if (parent != &top_cpuset) {
update_tasks_cpumask(parent);
}
if (parent->child_ecpus_count) {
update_sibling_cpumasks(parent, cs, &tmpmask);
}
rebuild_sched_domains_locked();
out:
if (!err) {
spin_lock_irq(&callback_lock);
cs->partition_root_state = new_prs;
spin_unlock_irq(&callback_lock);
}
free_cpumasks(NULL, &tmpmask);
return err;
}
* Frequency meter - How fast is some event occurring?
*
* These routines manage a digitally filtered, constant time based,
* event frequency meter. There are four routines:
* fmeter_init() - initialize a frequency meter.
* fmeter_markevent() - called each time the event happens.
* fmeter_getrate() - returns the recent rate of such events.
* fmeter_update() - internal routine used to update fmeter.
*
* A common data structure is passed to each of these routines,
* which is used to keep track of the state required to manage the
* frequency meter and its digital filter.
*
* The filter works on the number of events marked per unit time.
* The filter is single-pole low-pass recursive (IIR). The time unit
* is 1 second. Arithmetic is done using 32-bit integers scaled to
* simulate 3 decimal digits of precision (multiplied by 1000).
*
* With an FM_COEF of 933, and a time base of 1 second, the filter
* has a half-life of 10 seconds, meaning that if the events quit
* happening, then the rate returned from the fmeter_getrate()
* will be cut in half each 10 seconds, until it converges to zero.
*
* It is not worth doing a real infinitely recursive filter. If more
* than FM_MAXTICKS ticks have elapsed since the last filter event,
* just compute FM_MAXTICKS ticks worth, by which point the level
* will be stable.
*
* Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
* arithmetic overflow in the fmeter_update() routine.
*
* Given the simple 32 bit integer arithmetic used, this meter works
* best for reporting rates between one per millisecond (msec) and
* one per 32 (approx) seconds. At constant rates faster than one
* per msec it maxes out at values just under 1,000,000. At constant
* rates between one per msec, and one per second it will stabilize
* to a value N*1000, where N is the rate of events per second.
* At constant rates between one per second and one per 32 seconds,
* it will be choppy, moving up on the seconds that have an event,
* and then decaying until the next event. At rates slower than
* about one in 32 seconds, it decays all the way back to zero between
* each event.
*/
#define FM_COEF 933
#define FM_MAXTICKS ((u32)99)
#define FM_MAXCNT 1000000
#define FM_SCALE 1000
static void fmeter_init(struct fmeter *fmp)
{
fmp->cnt = 0;
fmp->val = 0;
fmp->time = 0;
spin_lock_init(&fmp->lock);
}
static void fmeter_update(struct fmeter *fmp)
{
time64_t now;
u32 ticks;
now = ktime_get_seconds();
ticks = now - fmp->time;
if (ticks == 0) {
return;
}
ticks = min(FM_MAXTICKS, ticks);
while (ticks-- > 0) {
fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
}
fmp->time = now;
fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
fmp->cnt = 0;
}
static void fmeter_markevent(struct fmeter *fmp)
{
spin_lock(&fmp->lock);
fmeter_update(fmp);
fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
spin_unlock(&fmp->lock);
}
static int fmeter_getrate(struct fmeter *fmp)
{
int val;
spin_lock(&fmp->lock);
fmeter_update(fmp);
val = fmp->val;
spin_unlock(&fmp->lock);
return val;
}
static struct cpuset *cpuset_attach_old_cs;
static int cpuset_can_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
struct cpuset *cs;
struct task_struct *task;
int ret;
cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
cs = css_cs(css);
mutex_lock(&cpuset_mutex);
ret = -ENOSPC;
if (!is_in_v2_mode() && (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))) {
goto out_unlock;
}
cgroup_taskset_for_each(task, css, tset)
{
ret = task_can_attach(task, cs->effective_cpus);
if (ret) {
goto out_unlock;
}
ret = security_task_setscheduler(task);
if (ret) {
goto out_unlock;
}
}
* Mark attach is in progress. This makes validate_change() fail
* changes which zero cpus/mems_allowed.
*/
cs->attach_in_progress++;
ret = 0;
out_unlock:
mutex_unlock(&cpuset_mutex);
return ret;
}
static void cpuset_cancel_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
cgroup_taskset_first(tset, &css);
mutex_lock(&cpuset_mutex);
css_cs(css)->attach_in_progress--;
mutex_unlock(&cpuset_mutex);
}
* Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach()
* but we can't allocate it dynamically there. Define it global and
* allocate from cpuset_init().
*/
static cpumask_var_t cpus_attach;
static void cpuset_attach(struct cgroup_taskset *tset)
{
static nodemask_t cpuset_attach_nodemask_to;
struct task_struct *task;
struct task_struct *leader;
struct cgroup_subsys_state *css;
struct cpuset *cs;
struct cpuset *oldcs = cpuset_attach_old_cs;
cgroup_taskset_first(tset, &css);
cs = css_cs(css);
mutex_lock(&cpuset_mutex);
guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
cgroup_taskset_for_each(task, css, tset)
{
if (cs != &top_cpuset) {
guarantee_online_cpus(task, cpus_attach);
} else {
cpumask_copy(cpus_attach, task_cpu_possible_mask(task));
}
* can_attach beforehand should guarantee that this doesn't
* fail. have a better way to handle failure here
*/
WARN_ON_ONCE(update_cpus_allowed(cs, task, cpus_attach));
cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
cpuset_update_task_spread_flag(cs, task);
}
* Change mm for all threadgroup leaders. This is expensive and may
* sleep and should be moved outside migration path proper.
*/
cpuset_attach_nodemask_to = cs->effective_mems;
cgroup_taskset_for_each_leader(leader, css, tset)
{
struct mm_struct *mm = get_task_mm(leader);
if (mm) {
mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
* old_mems_allowed is the same with mems_allowed
* here, except if this task is being moved
* automatically due to hotplug. In that case
* @mems_allowed has been updated and is empty, so
* @old_mems_allowed is the right nodesets that we
* migrate mm from.
*/
if (is_memory_migrate(cs)) {
cpuset_migrate_mm(mm, &oldcs->old_mems_allowed, &cpuset_attach_nodemask_to);
} else {
mmput(mm);
}
}
}
cs->old_mems_allowed = cpuset_attach_nodemask_to;
cs->attach_in_progress--;
if (!cs->attach_in_progress) {
wake_up(&cpuset_attach_wq);
}
mutex_unlock(&cpuset_mutex);
}
typedef enum {
FILE_MEMORY_MIGRATE,
FILE_CPULIST,
FILE_MEMLIST,
FILE_EFFECTIVE_CPULIST,
FILE_EFFECTIVE_MEMLIST,
FILE_SUBPARTS_CPULIST,
FILE_CPU_EXCLUSIVE,
FILE_MEM_EXCLUSIVE,
FILE_MEM_HARDWALL,
FILE_SCHED_LOAD_BALANCE,
FILE_PARTITION_ROOT,
FILE_SCHED_RELAX_DOMAIN_LEVEL,
FILE_MEMORY_PRESSURE_ENABLED,
FILE_MEMORY_PRESSURE,
FILE_SPREAD_PAGE,
FILE_SPREAD_SLAB,
} cpuset_filetype_t;
static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft, u64 val)
{
struct cpuset *cs = css_cs(css);
cpuset_filetype_t type = cft->private;
int retval = 0;
get_online_cpus();
mutex_lock(&cpuset_mutex);
if (!is_cpuset_online(cs)) {
retval = -ENODEV;
goto out_unlock;
}
switch (type) {
case FILE_CPU_EXCLUSIVE:
retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
break;
case FILE_MEM_EXCLUSIVE:
retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
break;
case FILE_MEM_HARDWALL:
retval = update_flag(CS_MEM_HARDWALL, cs, val);
break;
case FILE_SCHED_LOAD_BALANCE:
retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
break;
case FILE_MEMORY_MIGRATE:
retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
break;
case FILE_MEMORY_PRESSURE_ENABLED:
cpuset_memory_pressure_enabled = !!val;
break;
case FILE_SPREAD_PAGE:
retval = update_flag(CS_SPREAD_PAGE, cs, val);
break;
case FILE_SPREAD_SLAB:
retval = update_flag(CS_SPREAD_SLAB, cs, val);
break;
default:
retval = -EINVAL;
break;
}
out_unlock:
mutex_unlock(&cpuset_mutex);
put_online_cpus();
return retval;
}
static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft, s64 val)
{
struct cpuset *cs = css_cs(css);
cpuset_filetype_t type = cft->private;
int retval = -ENODEV;
get_online_cpus();
mutex_lock(&cpuset_mutex);
if (!is_cpuset_online(cs)) {
goto out_unlock;
}
switch (type) {
case FILE_SCHED_RELAX_DOMAIN_LEVEL:
retval = update_relax_domain_level(cs, val);
break;
default:
retval = -EINVAL;
break;
}
out_unlock:
mutex_unlock(&cpuset_mutex);
put_online_cpus();
return retval;
}
* Common handling for a write to a "cpus" or "mems" file.
*/
static ssize_t cpuset_write_resmask(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off)
{
struct cpuset *cs = css_cs(of_css(of));
struct cpuset *trialcs;
int retval = -ENODEV;
buf = strstrip(buf);
* CPU or memory hotunplug may leave @cs w/o any execution
* resources, in which case the hotplug code asynchronously updates
* configuration and transfers all tasks to the nearest ancestor
* which can execute.
*
* As writes to "cpus" or "mems" may restore @cs's execution
* resources, wait for the previously scheduled operations before
* proceeding, so that we don't end up keep removing tasks added
* after execution capability is restored.
*
* cpuset_hotplug_work calls back into cgroup core via
* cgroup_transfer_tasks() and waiting for it from a cgroupfs
* operation like this one can lead to a deadlock through kernfs
* active_ref protection. Let's break the protection. Losing the
* protection is okay as we check whether @cs is online after
* grabbing cpuset_mutex anyway. This only happens on the legacy
* hierarchies.
*/
css_get(&cs->css);
kernfs_break_active_protection(of->kn);
flush_work(&cpuset_hotplug_work);
get_online_cpus();
mutex_lock(&cpuset_mutex);
if (!is_cpuset_online(cs)) {
goto out_unlock;
}
trialcs = alloc_trial_cpuset(cs);
if (!trialcs) {
retval = -ENOMEM;
goto out_unlock;
}
switch (of_cft(of)->private) {
case FILE_CPULIST:
retval = update_cpumask(cs, trialcs, buf);
break;
case FILE_MEMLIST:
retval = update_nodemask(cs, trialcs, buf);
break;
default:
retval = -EINVAL;
break;
}
free_cpuset(trialcs);
out_unlock:
mutex_unlock(&cpuset_mutex);
put_online_cpus();
kernfs_unbreak_active_protection(of->kn);
css_put(&cs->css);
flush_workqueue(cpuset_migrate_mm_wq);
return retval ?: nbytes;
}
* These ascii lists should be read in a single call, by using a user
* buffer large enough to hold the entire map. If read in smaller
* chunks, there is no guarantee of atomicity. Since the display format
* used, list of ranges of sequential numbers, is variable length,
* and since these maps can change value dynamically, one could read
* gibberish by doing partial reads while a list was changing.
*/
static int cpuset_common_seq_show(struct seq_file *sf, void *v)
{
struct cpuset *cs = css_cs(seq_css(sf));
cpuset_filetype_t type = seq_cft(sf)->private;
int ret = 0;
spin_lock_irq(&callback_lock);
switch (type) {
case FILE_CPULIST:
seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_requested));
break;
case FILE_MEMLIST:
seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed));
break;
case FILE_EFFECTIVE_CPULIST:
seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus));
break;
case FILE_EFFECTIVE_MEMLIST:
seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems));
break;
case FILE_SUBPARTS_CPULIST:
seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->subparts_cpus));
break;
default:
ret = -EINVAL;
}
spin_unlock_irq(&callback_lock);
return ret;
}
static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
{
struct cpuset *cs = css_cs(css);
cpuset_filetype_t type = cft->private;
switch (type) {
case FILE_CPU_EXCLUSIVE:
return is_cpu_exclusive(cs);
case FILE_MEM_EXCLUSIVE:
return is_mem_exclusive(cs);
case FILE_MEM_HARDWALL:
return is_mem_hardwall(cs);
case FILE_SCHED_LOAD_BALANCE:
return is_sched_load_balance(cs);
case FILE_MEMORY_MIGRATE:
return is_memory_migrate(cs);
case FILE_MEMORY_PRESSURE_ENABLED:
return cpuset_memory_pressure_enabled;
case FILE_MEMORY_PRESSURE:
return fmeter_getrate(&cs->fmeter);
case FILE_SPREAD_PAGE:
return is_spread_page(cs);
case FILE_SPREAD_SLAB:
return is_spread_slab(cs);
default:
BUG();
}
return 0;
}
static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
{
struct cpuset *cs = css_cs(css);
cpuset_filetype_t type = cft->private;
switch (type) {
case FILE_SCHED_RELAX_DOMAIN_LEVEL:
return cs->relax_domain_level;
default:
BUG();
}
return 0;
}
static int sched_partition_show(struct seq_file *seq, void *v)
{
struct cpuset *cs = css_cs(seq_css(seq));
switch (cs->partition_root_state) {
case PRS_ENABLED:
seq_puts(seq, "root\n");
break;
case PRS_DISABLED:
seq_puts(seq, "member\n");
break;
case PRS_ERROR:
seq_puts(seq, "root invalid\n");
break;
default:
break;
}
return 0;
}
static ssize_t sched_partition_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off)
{
struct cpuset *cs = css_cs(of_css(of));
int val;
int retval = -ENODEV;
buf = strstrip(buf);
* Convert "root" to ENABLED, and convert "member" to DISABLED.
*/
if (!strcmp(buf, "root")) {
val = PRS_ENABLED;
} else if (!strcmp(buf, "member")) {
val = PRS_DISABLED;
} else {
return -EINVAL;
}
css_get(&cs->css);
get_online_cpus();
mutex_lock(&cpuset_mutex);
if (!is_cpuset_online(cs)) {
goto out_unlock;
}
retval = update_prstate(cs, val);
out_unlock:
mutex_unlock(&cpuset_mutex);
put_online_cpus();
css_put(&cs->css);
return retval ?: nbytes;
}
* for the common functions, 'private' gives the type of file
*/
static struct cftype legacy_files[] = {
{
.name = "cpus",
.seq_show = cpuset_common_seq_show,
.write = cpuset_write_resmask,
.max_write_len = (100U + 6 * NR_CPUS),
.private = FILE_CPULIST,
},
{
.name = "mems",
.seq_show = cpuset_common_seq_show,
.write = cpuset_write_resmask,
.max_write_len = (100U + 6 * MAX_NUMNODES),
.private = FILE_MEMLIST,
},
{
.name = "effective_cpus",
.seq_show = cpuset_common_seq_show,
.private = FILE_EFFECTIVE_CPULIST,
},
{
.name = "effective_mems",
.seq_show = cpuset_common_seq_show,
.private = FILE_EFFECTIVE_MEMLIST,
},
{
.name = "cpu_exclusive",
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
.private = FILE_CPU_EXCLUSIVE,
},
{
.name = "mem_exclusive",
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
.private = FILE_MEM_EXCLUSIVE,
},
{
.name = "mem_hardwall",
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
.private = FILE_MEM_HARDWALL,
},
{
.name = "sched_load_balance",
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
.private = FILE_SCHED_LOAD_BALANCE,
},
{
.name = "sched_relax_domain_level",
.read_s64 = cpuset_read_s64,
.write_s64 = cpuset_write_s64,
.private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
},
{
.name = "memory_migrate",
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
.private = FILE_MEMORY_MIGRATE,
},
{
.name = "memory_pressure",
.read_u64 = cpuset_read_u64,
.private = FILE_MEMORY_PRESSURE,
},
{
.name = "memory_spread_page",
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
.private = FILE_SPREAD_PAGE,
},
{
.name = "memory_spread_slab",
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
.private = FILE_SPREAD_SLAB,
},
{
.name = "memory_pressure_enabled",
.flags = CFTYPE_ONLY_ON_ROOT,
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
.private = FILE_MEMORY_PRESSURE_ENABLED,
},
{}
};
* This is currently a minimal set for the default hierarchy. It can be
* expanded later on by migrating more features and control files from v1.
*/
static struct cftype dfl_files[] = {
{
.name = "cpus",
.seq_show = cpuset_common_seq_show,
.write = cpuset_write_resmask,
.max_write_len = (100U + 6 * NR_CPUS),
.private = FILE_CPULIST,
.flags = CFTYPE_NOT_ON_ROOT,
},
{
.name = "mems",
.seq_show = cpuset_common_seq_show,
.write = cpuset_write_resmask,
.max_write_len = (100U + 6 * MAX_NUMNODES),
.private = FILE_MEMLIST,
.flags = CFTYPE_NOT_ON_ROOT,
},
{
.name = "cpus.effective",
.seq_show = cpuset_common_seq_show,
.private = FILE_EFFECTIVE_CPULIST,
},
{
.name = "mems.effective",
.seq_show = cpuset_common_seq_show,
.private = FILE_EFFECTIVE_MEMLIST,
},
{
.name = "cpus.partition",
.seq_show = sched_partition_show,
.write = sched_partition_write,
.private = FILE_PARTITION_ROOT,
.flags = CFTYPE_NOT_ON_ROOT,
},
{
.name = "cpus.subpartitions",
.seq_show = cpuset_common_seq_show,
.private = FILE_SUBPARTS_CPULIST,
.flags = CFTYPE_DEBUG,
},
{}
};
* cpuset_css_alloc - allocate a cpuset css
* cgrp: control group that the new cpuset will be part of
*/
static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
{
struct cpuset *cs;
if (!parent_css) {
return &top_cpuset.css;
}
cs = kzalloc(sizeof(*cs), GFP_KERNEL);
if (!cs) {
return ERR_PTR(-ENOMEM);
}
if (alloc_cpumasks(cs, NULL)) {
kfree(cs);
return ERR_PTR(-ENOMEM);
}
set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
nodes_clear(cs->mems_allowed);
nodes_clear(cs->effective_mems);
fmeter_init(&cs->fmeter);
cs->relax_domain_level = -1;
return &cs->css;
}
static int cpuset_css_online(struct cgroup_subsys_state *css)
{
struct cpuset *cs = css_cs(css);
struct cpuset *parent = parent_cs(cs);
struct cpuset *tmp_cs;
struct cgroup_subsys_state *pos_css;
if (!parent) {
return 0;
}
get_online_cpus();
mutex_lock(&cpuset_mutex);
set_bit(CS_ONLINE, &cs->flags);
if (is_spread_page(parent)) {
set_bit(CS_SPREAD_PAGE, &cs->flags);
}
if (is_spread_slab(parent)) {
set_bit(CS_SPREAD_SLAB, &cs->flags);
}
cpuset_inc();
spin_lock_irq(&callback_lock);
if (is_in_v2_mode()) {
cpumask_copy(cs->effective_cpus, parent->effective_cpus);
cs->effective_mems = parent->effective_mems;
cs->use_parent_ecpus = true;
parent->child_ecpus_count++;
}
spin_unlock_irq(&callback_lock);
if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags)) {
goto out_unlock;
}
* Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
* set. This flag handling is implemented in cgroup core for
* histrical reasons - the flag may be specified during mount.
*
* Currently, if any sibling cpusets have exclusive cpus or mem, we
* refuse to clone the configuration - thereby refusing the task to
* be entered, and as a result refusing the sys_unshare() or
* clone() which initiated it. If this becomes a problem for some
* users who wish to allow that scenario, then this could be
* changed to grant parent->cpus_allowed-sibling_cpus_exclusive
* (and likewise for mems) to the new cgroup.
*/
rcu_read_lock();
cpuset_for_each_child(tmp_cs, pos_css, parent) {
if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
rcu_read_unlock();
goto out_unlock;
}
}
rcu_read_unlock();
spin_lock_irq(&callback_lock);
cs->mems_allowed = parent->mems_allowed;
cs->effective_mems = parent->mems_allowed;
cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
cpumask_copy(cs->cpus_requested, parent->cpus_requested);
cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
spin_unlock_irq(&callback_lock);
out_unlock:
mutex_unlock(&cpuset_mutex);
put_online_cpus();
return 0;
}
* If the cpuset being removed has its flag 'sched_load_balance'
* enabled, then simulate turning sched_load_balance off, which
* will call rebuild_sched_domains_locked(). That is not needed
* in the default hierarchy where only changes in partition
* will cause repartitioning.
*
* If the cpuset has the 'sched.partition' flag enabled, simulate
* turning 'sched.partition" off.
*/
static void cpuset_css_offline(struct cgroup_subsys_state *css)
{
struct cpuset *cs = css_cs(css);
get_online_cpus();
mutex_lock(&cpuset_mutex);
if (is_partition_root(cs)) {
update_prstate(cs, 0);
}
if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && is_sched_load_balance(cs)) {
update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
}
if (cs->use_parent_ecpus) {
struct cpuset *parent = parent_cs(cs);
cs->use_parent_ecpus = false;
parent->child_ecpus_count--;
}
cpuset_dec();
clear_bit(CS_ONLINE, &cs->flags);
mutex_unlock(&cpuset_mutex);
put_online_cpus();
}
static void cpuset_css_free(struct cgroup_subsys_state *css)
{
struct cpuset *cs = css_cs(css);
free_cpuset(cs);
}
static void cpuset_bind(struct cgroup_subsys_state *root_css)
{
mutex_lock(&cpuset_mutex);
spin_lock_irq(&callback_lock);
if (is_in_v2_mode()) {
cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
top_cpuset.mems_allowed = node_possible_map;
} else {
cpumask_copy(top_cpuset.cpus_allowed, top_cpuset.effective_cpus);
top_cpuset.mems_allowed = top_cpuset.effective_mems;
}
spin_unlock_irq(&callback_lock);
mutex_unlock(&cpuset_mutex);
}
* Make sure the new task conform to the current state of its parent,
* which could have been changed by cpuset just after it inherits the
* state from the parent and before it sits on the cgroup's task list.
*/
static void cpuset_fork(struct task_struct *task)
{
int inherit_cpus = 0;
if (task_css_is_root(task, cpuset_cgrp_id)) {
return;
}
task->mems_allowed = current->mems_allowed;
}
struct cgroup_subsys cpuset_cgrp_subsys = {
.css_alloc = cpuset_css_alloc,
.css_online = cpuset_css_online,
.css_offline = cpuset_css_offline,
.css_free = cpuset_css_free,
.can_attach = cpuset_can_attach,
.cancel_attach = cpuset_cancel_attach,
.attach = cpuset_attach,
.post_attach = cpuset_post_attach,
.bind = cpuset_bind,
.fork = cpuset_fork,
.legacy_cftypes = legacy_files,
.dfl_cftypes = dfl_files,
.early_init = true,
.threaded = true,
};
* cpuset_init - initialize cpusets at system boot
*
* Description: Initialize top_cpuset
**/
int __init cpuset_init(void)
{
BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_requested, GFP_KERNEL));
BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));
cpumask_setall(top_cpuset.cpus_allowed);
cpumask_setall(top_cpuset.cpus_requested);
nodes_setall(top_cpuset.mems_allowed);
cpumask_setall(top_cpuset.effective_cpus);
nodes_setall(top_cpuset.effective_mems);
fmeter_init(&top_cpuset.fmeter);
set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
top_cpuset.relax_domain_level = -1;
BUG_ON(!alloc_cpumask_var(&cpus_attach, GFP_KERNEL));
return 0;
}
* If CPU and/or memory hotplug handlers, below, unplug any CPUs
* or memory nodes, we need to walk over the cpuset hierarchy,
* removing that CPU or node from all cpusets. If this removes the
* last CPU or node from a cpuset, then move the tasks in the empty
* cpuset to its next-highest non-empty parent.
*/
static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
{
struct cpuset *parent;
* Find its next-highest non-empty parent, (top cpuset
* has online cpus, so can't be empty).
*/
parent = parent_cs(cs);
while (cpumask_empty(parent->cpus_allowed) || nodes_empty(parent->mems_allowed)) {
parent = parent_cs(parent);
}
if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
pr_cont_cgroup_name(cs->css.cgroup);
pr_cont("\n");
}
}
static void hotplug_update_tasks_legacy(struct cpuset *cs, struct cpumask *new_cpus, nodemask_t *new_mems,
bool cpus_updated, bool mems_updated)
{
bool is_empty;
spin_lock_irq(&callback_lock);
cpumask_copy(cs->cpus_allowed, new_cpus);
cpumask_copy(cs->effective_cpus, new_cpus);
cs->mems_allowed = *new_mems;
cs->effective_mems = *new_mems;
spin_unlock_irq(&callback_lock);
* Don't call update_tasks_cpumask() if the cpuset becomes empty,
* as the tasks will be migratecd to an ancestor.
*/
if (cpus_updated && !cpumask_empty(cs->cpus_allowed)) {
update_tasks_cpumask(cs);
}
if (mems_updated && !nodes_empty(cs->mems_allowed)) {
update_tasks_nodemask(cs);
}
is_empty = cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed);
mutex_unlock(&cpuset_mutex);
* Move tasks to the nearest ancestor with execution resources,
* This is full cgroup operation which will also call back into
* cpuset. Should be done outside any lock.
*/
if (is_empty) {
remove_tasks_in_empty_cpuset(cs);
}
mutex_lock(&cpuset_mutex);
}
static void hotplug_update_tasks(struct cpuset *cs, struct cpumask *new_cpus, nodemask_t *new_mems, bool cpus_updated,
bool mems_updated)
{
if (cpumask_empty(new_cpus)) {
cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
}
if (nodes_empty(*new_mems)) {
*new_mems = parent_cs(cs)->effective_mems;
}
spin_lock_irq(&callback_lock);
cpumask_copy(cs->effective_cpus, new_cpus);
cs->effective_mems = *new_mems;
spin_unlock_irq(&callback_lock);
if (cpus_updated) {
update_tasks_cpumask(cs);
}
if (mems_updated) {
update_tasks_nodemask(cs);
}
}
static bool force_rebuild;
void cpuset_force_rebuild(void)
{
force_rebuild = true;
}
* cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
* @cs: cpuset in interest
* @tmp: the tmpmasks structure pointer
*
* Compare @cs's cpu and mem masks against top_cpuset and if some have gone
* offline, update @cs accordingly. If @cs ends up with no CPU or memory,
* all its tasks are moved to the nearest ancestor with both resources.
*/
static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp)
{
static cpumask_t new_cpus;
static nodemask_t new_mems;
bool cpus_updated;
bool mems_updated;
struct cpuset *parent;
while (1) {
wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
mutex_lock(&cpuset_mutex);
* We have raced with task attaching. We wait until attaching
* is finished, so we won't attach a task to an empty cpuset.
*/
if (cs->attach_in_progress) {
mutex_unlock(&cpuset_mutex);
continue;
}
break;
}
parent = parent_cs(cs);
compute_effective_cpumask(&new_cpus, cs, parent);
nodes_and(new_mems, cs->mems_allowed, parent->effective_mems);
if (cs->nr_subparts_cpus) {
* Make sure that CPUs allocated to child partitions
* do not show up in effective_cpus.
*/
cpumask_andnot(&new_cpus, &new_cpus, cs->subparts_cpus);
}
if (!tmp || !cs->partition_root_state) {
goto update_tasks;
}
* In the unlikely event that a partition root has empty
* effective_cpus or its parent becomes erroneous, we have to
* transition it to the erroneous state.
*/
if (is_partition_root(cs) && (cpumask_empty(&new_cpus) || (parent->partition_root_state == PRS_ERROR))) {
if (cs->nr_subparts_cpus) {
spin_lock_irq(&callback_lock);
cs->nr_subparts_cpus = 0;
cpumask_clear(cs->subparts_cpus);
spin_unlock_irq(&callback_lock);
compute_effective_cpumask(&new_cpus, cs, parent);
}
* If the effective_cpus is empty because the child
* partitions take away all the CPUs, we can keep
* the current partition and let the child partitions
* fight for available CPUs.
*/
if ((parent->partition_root_state == PRS_ERROR) || cpumask_empty(&new_cpus)) {
update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp);
spin_lock_irq(&callback_lock);
cs->partition_root_state = PRS_ERROR;
spin_unlock_irq(&callback_lock);
}
cpuset_force_rebuild();
}
* On the other hand, an erroneous partition root may be transitioned
* back to a regular one or a partition root with no CPU allocated
* from the parent may change to erroneous.
*/
if (is_partition_root(parent) &&
((cs->partition_root_state == PRS_ERROR) || !cpumask_intersects(&new_cpus, parent->subparts_cpus)) &&
update_parent_subparts_cpumask(cs, partcmd_update, NULL, tmp)) {
cpuset_force_rebuild();
}
update_tasks:
cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
mems_updated = !nodes_equal(new_mems, cs->effective_mems);
if (is_in_v2_mode()) {
hotplug_update_tasks(cs, &new_cpus, &new_mems, cpus_updated, mems_updated);
} else {
hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems, cpus_updated, mems_updated);
}
mutex_unlock(&cpuset_mutex);
}
* cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
*
* This function is called after either CPU or memory configuration has
* changed and updates cpuset accordingly. The top_cpuset is always
* synchronized to cpu_active_mask and N_MEMORY, which is necessary in
* order to make cpusets transparent (of no affect) on systems that are
* actively using CPU hotplug but making no active use of cpusets.
*
* Non-root cpusets are only affected by offlining. If any CPUs or memory
* nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
* all descendants.
*
* Note that CPU offlining during suspend is ignored. We don't modify
* cpusets across suspend/resume cycles at all.
*/
void cpuset_hotplug_workfn(struct work_struct *work)
{
static cpumask_t new_cpus;
static nodemask_t new_mems;
bool cpus_updated, mems_updated;
bool on_dfl = is_in_v2_mode();
struct tmpmasks tmp, *ptmp = NULL;
if (on_dfl && !alloc_cpumasks(NULL, &tmp)) {
ptmp = &tmp;
}
mutex_lock(&cpuset_mutex);
cpumask_copy(&new_cpus, cpu_active_mask);
new_mems = node_states[N_MEMORY];
* If subparts_cpus is populated, it is likely that the check below
* will produce a false positive on cpus_updated when the cpu list
* isn't changed. It is extra work, but it is better to be safe.
*/
cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
* In the rare case that hotplug removes all the cpus in subparts_cpus,
* we assumed that cpus are updated.
*/
if (!cpus_updated && top_cpuset.nr_subparts_cpus) {
cpus_updated = true;
}
if (cpus_updated) {
spin_lock_irq(&callback_lock);
if (!on_dfl) {
cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
}
* Make sure that CPUs allocated to child partitions
* do not show up in effective_cpus. If no CPU is left,
* we clear the subparts_cpus & let the child partitions
* fight for the CPUs again.
*/
if (top_cpuset.nr_subparts_cpus) {
if (cpumask_subset(&new_cpus, top_cpuset.subparts_cpus)) {
top_cpuset.nr_subparts_cpus = 0;
cpumask_clear(top_cpuset.subparts_cpus);
} else {
cpumask_andnot(&new_cpus, &new_cpus, top_cpuset.subparts_cpus);
}
}
cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
spin_unlock_irq(&callback_lock);
}
if (mems_updated) {
spin_lock_irq(&callback_lock);
if (!on_dfl) {
top_cpuset.mems_allowed = new_mems;
}
top_cpuset.effective_mems = new_mems;
spin_unlock_irq(&callback_lock);
update_tasks_nodemask(&top_cpuset);
}
mutex_unlock(&cpuset_mutex);
if (cpus_updated || mems_updated) {
struct cpuset *cs;
struct cgroup_subsys_state *pos_css;
rcu_read_lock();
cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
if (cs == &top_cpuset || !css_tryget_online(&cs->css)) {
continue;
}
rcu_read_unlock();
cpuset_hotplug_update_tasks(cs, ptmp);
rcu_read_lock();
css_put(&cs->css);
}
rcu_read_unlock();
}
if (cpus_updated || force_rebuild) {
force_rebuild = false;
rebuild_sched_domains();
}
free_cpumasks(NULL, ptmp);
}
void cpuset_update_active_cpus(void)
{
* We're inside cpu hotplug critical region which usually nests
* inside cgroup synchronization. Bounce actual hotplug processing
* to a work item to avoid reverse locking order.
*/
schedule_work(&cpuset_hotplug_work);
}
void cpuset_wait_for_hotplug(void)
{
flush_work(&cpuset_hotplug_work);
}
EXPORT_SYMBOL_GPL(cpuset_wait_for_hotplug);
* Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
* Call this routine anytime after node_states[N_MEMORY] changes.
* See cpuset_update_active_cpus() for CPU hotplug handling.
*/
static int cpuset_track_online_nodes(struct notifier_block *self, unsigned long action, void *arg)
{
schedule_work(&cpuset_hotplug_work);
return NOTIFY_OK;
}
static struct notifier_block cpuset_track_online_nodes_nb = {
.notifier_call = cpuset_track_online_nodes, .priority = 10,
};
* cpuset_init_smp - initialize cpus_allowed
*
* Description: Finish top cpuset after cpu, node maps are initialized
*/
void __init cpuset_init_smp(void)
{
* cpus_allowd/mems_allowed set to v2 values in the initial
* cpuset_bind() call will be reset to v1 values in another
* cpuset_bind() call when v1 cpuset is mounted.
*/
top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
top_cpuset.effective_mems = node_states[N_MEMORY];
register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0);
BUG_ON(!cpuset_migrate_mm_wq);
}
* cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
* @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
* @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
*
* Description: Returns the cpumask_var_t cpus_allowed of the cpuset
* attached to the specified @tsk. Guaranteed to return some non-empty
* subset of cpu_online_mask, even if this means going outside the
* tasks cpuset.
**/
void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
{
unsigned long flags;
spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
guarantee_online_cpus(tsk, pmask);
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
}
EXPORT_SYMBOL_GPL(cpuset_cpus_allowed);
* cpuset_cpus_allowed_fallback - final fallback before complete catastrophe.
* @tsk: pointer to task_struct with which the scheduler is struggling
*
* Description: In the case that the scheduler cannot find an allowed cpu in
* tsk->cpus_allowed, we fall back to task_cs(tsk)->cpus_allowed. In legacy
* mode however, this value is the same as task_cs(tsk)->effective_cpus,
* which will not contain a sane cpumask during cases such as cpu hotplugging.
* This is the absolute last resort for the scheduler and it is only used if
* _every_ other avenue has been traveled.
**/
void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
{
const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
const struct cpumask *cs_mask;
rcu_read_lock();
cs_mask = task_cs(tsk)->cpus_allowed;
if (!is_in_v2_mode() || !cpumask_subset(cs_mask, possible_mask)) {
goto unlock;
}
do_set_cpus_allowed(tsk, cs_mask);
unlock:
rcu_read_unlock();
* We own tsk->cpus_allowed, nobody can change it under us.
*
* But we used cs && cs->cpus_allowed lockless and thus can
* race with cgroup_attach_task() or update_cpumask() and get
* the wrong tsk->cpus_allowed. However, both cases imply the
* subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
* which takes task_rq_lock().
*
* If we are called after it dropped the lock we must see all
* changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
* set any mask even if it is not right from task_cs() pov,
* the pending set_cpus_allowed_ptr() will fix things.
*
* select_fallback_rq() will fix things ups and set cpu_possible_mask
* if required.
*/
}
void __init cpuset_init_current_mems_allowed(void)
{
nodes_setall(current->mems_allowed);
}
* cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
* @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
*
* Description: Returns the nodemask_t mems_allowed of the cpuset
* attached to the specified @tsk. Guaranteed to return some non-empty
* subset of node_states[N_MEMORY], even if this means going outside the
* tasks cpuset.
**/
nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
{
nodemask_t mask;
unsigned long flags;
spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
guarantee_online_mems(task_cs(tsk), &mask);
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
return mask;
}
* cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
* @nodemask: the nodemask to be checked
*
* Are any of the nodes in the nodemask allowed in current->mems_allowed?
*/
int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
{
return nodes_intersects(*nodemask, current->mems_allowed);
}
* nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
* mem_hardwall ancestor to the specified cpuset. Call holding
* callback_lock. If no ancestor is mem_exclusive or mem_hardwall
* (an unusual configuration), then returns the root cpuset.
*/
static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
{
while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs)) {
cs = parent_cs(cs);
}
return cs;
}
* cpuset_node_allowed - Can we allocate on a memory node?
* @node: is this an allowed node?
* @gfp_mask: memory allocation flags
*
* If we're in interrupt, yes, we can always allocate. If @node is set in
* current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this
* node is set in the nearest hardwalled cpuset ancestor to current's cpuset,
* yes. If current has access to memory reserves as an oom victim, yes.
* Otherwise, no.
*
* GFP_USER allocations are marked with the __GFP_HARDWALL bit,
* and do not allow allocations outside the current tasks cpuset
* unless the task has been OOM killed.
* GFP_KERNEL allocations are not so marked, so can escape to the
* nearest enclosing hardwalled ancestor cpuset.
*
* Scanning up parent cpusets requires callback_lock. The
* __alloc_pages() routine only calls here with __GFP_HARDWALL bit
* _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
* current tasks mems_allowed came up empty on the first pass over
* the zonelist. So only GFP_KERNEL allocations, if all nodes in the
* cpuset are short of memory, might require taking the callback_lock.
*
* The first call here from mm/page_alloc:get_page_from_freelist()
* has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
* so no allocation on a node outside the cpuset is allowed (unless
* in interrupt, of course).
*
* The second pass through get_page_from_freelist() doesn't even call
* here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
* variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
* in alloc_flags. That logic and the checks below have the combined
* affect that:
* in_interrupt - any node ok (current task context irrelevant)
* GFP_ATOMIC - any node ok
* tsk_is_oom_victim - any node ok
* GFP_KERNEL - any node in enclosing hardwalled cpuset ok
* GFP_USER - only nodes in current tasks mems allowed ok.
*/
bool _cpuset_node_allowed(int node, gfp_t gfp_mask)
{
struct cpuset *cs;
int allowed;
unsigned long flags;
if (in_interrupt()) {
return true;
}
if (node_isset(node, current->mems_allowed)) {
return true;
}
* Allow tasks that have access to memory reserves because they have
* been OOM killed to get memory anywhere.
*/
if (unlikely(tsk_is_oom_victim(current))) {
return true;
}
if (gfp_mask & __GFP_HARDWALL) {
return false;
}
if (current->flags & PF_EXITING) {
return true;
}
spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
cs = nearest_hardwall_ancestor(task_cs(current));
allowed = node_isset(node, cs->mems_allowed);
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
return allowed;
}
* cpuset_mem_spread_node() - On which node to begin search for a file page
* cpuset_slab_spread_node() - On which node to begin search for a slab page
*
* If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
* tasks in a cpuset with is_spread_page or is_spread_slab set),
* and if the memory allocation used cpuset_mem_spread_node()
* to determine on which node to start looking, as it will for
* certain page cache or slab cache pages such as used for file
* system buffers and inode caches, then instead of starting on the
* local node to look for a free page, rather spread the starting
* node around the tasks mems_allowed nodes.
*
* We don't have to worry about the returned node being offline
* because "it can't happen", and even if it did, it would be ok.
*
* The routines calling guarantee_online_mems() are careful to
* only set nodes in task->mems_allowed that are online. So it
* should not be possible for the following code to return an
* offline node. But if it did, that would be ok, as this routine
* is not returning the node where the allocation must be, only
* the node where the search should start. The zonelist passed to
* __alloc_pages() will include all nodes. If the slab allocator
* is passed an offline node, it will fall back to the local node.
* See kmem_cache_alloc_node().
*/
static int cpuset_spread_node(int *rotor)
{
return *rotor = next_node_in(*rotor, current->mems_allowed);
}
int cpuset_mem_spread_node(void)
{
if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE) {
current->cpuset_mem_spread_rotor = node_random(¤t->mems_allowed);
}
return cpuset_spread_node(¤t->cpuset_mem_spread_rotor);
}
int cpuset_slab_spread_node(void)
{
if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE) {
current->cpuset_slab_spread_rotor = node_random(¤t->mems_allowed);
}
return cpuset_spread_node(¤t->cpuset_slab_spread_rotor);
}
EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
* cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
* @tsk1: pointer to task_struct of some task.
* @tsk2: pointer to task_struct of some other task.
*
* Description: Return true if @tsk1's mems_allowed intersects the
* mems_allowed of @tsk2. Used by the OOM killer to determine if
* one of the task's memory usage might impact the memory available
* to the other.
**/
int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, const struct task_struct *tsk2)
{
return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
}
* cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed
*
* Description: Prints current's name, cpuset name, and cached copy of its
* mems_allowed to the kernel log.
*/
void cpuset_print_current_mems_allowed(void)
{
struct cgroup *cgrp;
rcu_read_lock();
cgrp = task_cs(current)->css.cgroup;
pr_cont(",cpuset=");
pr_cont_cgroup_name(cgrp);
pr_cont(",mems_allowed=%*pbl", nodemask_pr_args(¤t->mems_allowed));
rcu_read_unlock();
}
* Collection of memory_pressure is suppressed unless
* this flag is enabled by writing "1" to the special
* cpuset file 'memory_pressure_enabled' in the root cpuset.
*/
int cpuset_memory_pressure_enabled __read_mostly;
* cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
*
* Keep a running average of the rate of synchronous (direct)
* page reclaim efforts initiated by tasks in each cpuset.
*
* This represents the rate at which some task in the cpuset
* ran low on memory on all nodes it was allowed to use, and
* had to enter the kernels page reclaim code in an effort to
* create more free memory by tossing clean pages or swapping
* or writing dirty pages.
*
* Display to user space in the per-cpuset read-only file
* "memory_pressure". Value displayed is an integer
* representing the recent rate of entry into the synchronous
* (direct) page reclaim by any task attached to the cpuset.
**/
void _cpuset_memory_pressure_bump(void)
{
rcu_read_lock();
fmeter_markevent(&task_cs(current)->fmeter);
rcu_read_unlock();
}
#ifdef CONFIG_PROC_PID_CPUSET
* proc_cpuset_show()
* - Print tasks cpuset path into seq_file.
* - Used for /proc/<pid>/cpuset.
* - No need to task_lock(tsk) on this tsk->cpuset reference, as it
* doesn't really matter if tsk->cpuset changes after we read it,
* and we take cpuset_mutex, keeping cpuset_attach() from changing it
* anyway.
*/
int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *tsk)
{
char *buf;
struct cgroup_subsys_state *css;
int retval;
retval = -ENOMEM;
buf = kmalloc(PATH_MAX, GFP_KERNEL);
if (!buf) {
goto out;
}
css = task_get_css(tsk, cpuset_cgrp_id);
retval = cgroup_path_ns(css->cgroup, buf, PATH_MAX, current->nsproxy->cgroup_ns);
css_put(css);
if (retval >= PATH_MAX) {
retval = -ENAMETOOLONG;
}
if (retval < 0) {
goto out_free;
}
seq_puts(m, buf);
seq_putc(m, '\n');
retval = 0;
out_free:
kfree(buf);
out:
return retval;
}
#endif
void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
{
seq_printf(m, "Mems_allowed:\t%*pb\n", nodemask_pr_args(&task->mems_allowed));
seq_printf(m, "Mems_allowed_list:\t%*pbl\n", nodemask_pr_args(&task->mems_allowed));
}