linux/kernel/cgroup/cpuset.c
Linus Torvalds 1b96a41b42 Merge branch 'for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "There are several notable changes here:

   - Single thread migrating itself has been optimized so that it
     doesn't need threadgroup rwsem anymore.

   - Freezer optimization to avoid unnecessary frozen state changes.

   - cgroup ID unification so that cgroup fs ino is the only unique ID
     used for the cgroup and can be used to directly look up live
     cgroups through filehandle interface on 64bit ino archs. On 32bit
     archs, cgroup fs ino is still the only ID in use but it is only
     unique when combined with gen.

   - selftest and other changes"

* 'for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (24 commits)
  writeback: fix -Wformat compilation warnings
  docs: cgroup: mm: Fix spelling of "list"
  cgroup: fix incorrect WARN_ON_ONCE() in cgroup_setup_root()
  cgroup: use cgrp->kn->id as the cgroup ID
  kernfs: use 64bit inos if ino_t is 64bit
  kernfs: implement custom exportfs ops and fid type
  kernfs: combine ino/id lookup functions into kernfs_find_and_get_node_by_id()
  kernfs: convert kernfs_node->id from union kernfs_node_id to u64
  kernfs: kernfs_find_and_get_node_by_ino() should only look up activated nodes
  kernfs: use dumber locking for kernfs_find_and_get_node_by_ino()
  netprio: use css ID instead of cgroup ID
  writeback: use ino_t for inodes in tracepoints
  kernfs: fix ino wrap-around detection
  kselftests: cgroup: Avoid the reuse of fd after it is deallocated
  cgroup: freezer: don't change task and cgroups status unnecessarily
  cgroup: use cgroup->last_bstat instead of cgroup->bstat_pending for consistency
  cgroup: remove cgroup_enable_task_cg_lists() optimization
  cgroup: pids: use atomic64_t for pids->limit
  selftests: cgroup: Run test_core under interfering stress
  selftests: cgroup: Add task migration tests
  ...
2019-11-25 19:23:46 -08:00

3620 lines
100 KiB
C

/*
* 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);
/* See "Frequency meter" comments, below. */
struct fmeter {
int cnt; /* unprocessed events count */
int val; /* most recent output value */
time64_t time; /* clock (secs) when val computed */
spinlock_t lock; /* guards read or write of above */
};
struct cpuset {
struct cgroup_subsys_state css;
unsigned long flags; /* "unsigned long" so bitops work */
/*
* On default hierarchy:
*
* The user-configured masks can only be changed by writing to
* cpuset.cpus and cpuset.mems, and won't be limited by the
* parent masks.
*
* The effective masks is the real masks that apply to the tasks
* in the cpuset. They may be changed if the configured masks are
* changed or hotplug happens.
*
* effective_mask == configured_mask & parent's effective_mask,
* and if it ends up empty, it will inherit the parent's mask.
*
*
* On legacy hierachy:
*
* The user-configured masks are always the same with effective masks.
*/
/* user-configured CPUs and Memory Nodes allow to tasks */
cpumask_var_t cpus_allowed;
nodemask_t mems_allowed;
/* effective CPUs and Memory Nodes allow to tasks */
cpumask_var_t effective_cpus;
nodemask_t effective_mems;
/*
* 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; /* memory_pressure filter */
/*
* Tasks are being attached to this cpuset. Used to prevent
* zeroing cpus/mems_allowed between ->can_attach() and ->attach().
*/
int attach_in_progress;
/* partition number for rebuild_sched_domains() */
int pn;
/* for custom sched domain */
int relax_domain_level;
/* number of CPUs in subparts_cpus */
int nr_subparts_cpus;
/* partition root state */
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; /* For partition root */
cpumask_var_t new_cpus; /* For update_cpumasks_hier() */
};
static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
{
return css ? container_of(css, struct cpuset, css) : NULL;
}
/* Retrieve the cpuset for a task */
static inline struct cpuset *task_cs(struct task_struct *task)
{
return css_cs(task_css(task, cpuset_cgrp_id));
}
static inline struct cpuset *parent_cs(struct cpuset *cs)
{
return css_cs(cs->css.parent);
}
/* bits in struct cpuset flags field */
typedef enum {
CS_ONLINE,
CS_CPU_EXCLUSIVE,
CS_MEM_EXCLUSIVE,
CS_MEM_HARDWALL,
CS_MEMORY_MIGRATE,
CS_SCHED_LOAD_BALANCE,
CS_SPREAD_PAGE,
CS_SPREAD_SLAB,
} cpuset_flagbits_t;
/* convenient tests for these bits */
static inline bool is_cpuset_online(struct cpuset *cs)
{
return test_bit(CS_ONLINE, &cs->flags) && !css_is_dying(&cs->css);
}
static inline int is_cpu_exclusive(const struct cpuset *cs)
{
return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
}
static inline int is_mem_exclusive(const struct cpuset *cs)
{
return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
}
static inline int is_mem_hardwall(const struct cpuset *cs)
{
return test_bit(CS_MEM_HARDWALL, &cs->flags);
}
static inline int is_sched_load_balance(const struct cpuset *cs)
{
return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
}
static inline int is_memory_migrate(const struct cpuset *cs)
{
return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
}
static inline int is_spread_page(const struct cpuset *cs)
{
return test_bit(CS_SPREAD_PAGE, &cs->flags);
}
static inline int is_spread_slab(const struct cpuset *cs)
{
return test_bit(CS_SPREAD_SLAB, &cs->flags);
}
static 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
*/
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.
*/
static void cpuset_hotplug_workfn(struct work_struct *work);
static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
/*
* Cgroup v2 behavior is used when on default hierarchy or the
* cgroup_v2_mode flag is set.
*/
static inline bool is_in_v2_mode(void)
{
return cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
(cpuset_cgrp_subsys.root->flags & CGRP_ROOT_CPUSET_V2_MODE);
}
/*
* Return in pmask the portion of a cpusets's cpus_allowed that
* are online. If none are online, walk up the cpuset hierarchy
* until we find one that does have some online cpus.
*
* One way or another, we guarantee to return some non-empty subset
* of cpu_online_mask.
*
* Call with callback_lock or cpuset_mutex held.
*/
static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
{
while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) {
cs = parent_cs(cs);
if (unlikely(!cs)) {
/*
* The top cpuset doesn't have any online cpu as a
* consequence of a race between cpuset_hotplug_work
* and cpu hotplug notifier. But we know the top
* cpuset's effective_cpus is on its way to to be
* identical to cpu_online_mask.
*/
cpumask_copy(pmask, cpu_online_mask);
return;
}
}
cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
}
/*
* Return in *pmask the portion of a cpusets's mems_allowed that
* are online, with memory. If none are online with memory, walk
* up the cpuset hierarchy until we find one that does have some
* online mems. The top cpuset always has some mems online.
*
* One way or another, we guarantee to return some non-empty subset
* of node_states[N_MEMORY].
*
* Call with callback_lock or cpuset_mutex held.
*/
static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
{
while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
cs = parent_cs(cs);
nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
}
/*
* update task's spread flag if cpuset's page/slab spread flag is set
*
* Call with callback_lock or cpuset_mutex held.
*/
static void cpuset_update_task_spread_flag(struct cpuset *cs,
struct task_struct *tsk)
{
if (is_spread_page(cs))
task_set_spread_page(tsk);
else
task_clear_spread_page(tsk);
if (is_spread_slab(cs))
task_set_spread_slab(tsk);
else
task_clear_spread_slab(tsk);
}
/*
* is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
*
* One cpuset is a subset of another if all its allowed CPUs and
* Memory Nodes are a subset of the other, and its exclusive flags
* are only set if the other's are set. Call holding cpuset_mutex.
*/
static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
{
return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
nodes_subset(p->mems_allowed, q->mems_allowed) &&
is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
is_mem_exclusive(p) <= is_mem_exclusive(q);
}
/**
* alloc_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;
if (cs) {
pmask1 = &cs->cpus_allowed;
pmask2 = &cs->effective_cpus;
pmask3 = &cs->subparts_cpus;
} 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;
return 0;
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->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->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();
/* Each of our child cpusets must be a subset of us */
ret = -EBUSY;
cpuset_for_each_child(c, css, cur)
if (!is_cpuset_subset(c, trial))
goto out;
/* Remaining checks don't apply to root cpuset */
ret = 0;
if (cur == &top_cpuset)
goto out;
par = parent_cs(cur);
/* On legacy hiearchy, we must be a subset of our parent cpuset. */
ret = -EACCES;
if (!is_in_v2_mode() && !is_cpuset_subset(trial, par))
goto out;
/*
* If either I or some sibling (!= me) is exclusive, we can't
* overlap
*/
ret = -EINVAL;
cpuset_for_each_child(c, css, par) {
if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
c != cur &&
cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
goto out;
if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
c != cur &&
nodes_intersects(trial->mems_allowed, c->mems_allowed))
goto out;
}
/*
* Cpusets with tasks - existing or newly being attached - can't
* be changed to have empty cpus_allowed or mems_allowed.
*/
ret = -ENOSPC;
if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) {
if (!cpumask_empty(cur->cpus_allowed) &&
cpumask_empty(trial->cpus_allowed))
goto out;
if (!nodes_empty(cur->mems_allowed) &&
nodes_empty(trial->mems_allowed))
goto out;
}
/*
* We can't shrink if we won't have enough room for SCHED_DEADLINE
* tasks.
*/
ret = -EBUSY;
if (is_cpu_exclusive(cur) &&
!cpuset_cpumask_can_shrink(cur->cpus_allowed,
trial->cpus_allowed))
goto out;
ret = 0;
out:
rcu_read_unlock();
return ret;
}
#ifdef CONFIG_SMP
/*
* Helper routine for generate_sched_domains().
* Do cpusets a, b have overlapping effective cpus_allowed masks?
*/
static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
{
return cpumask_intersects(a->effective_cpus, b->effective_cpus);
}
static void
update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
{
if (dattr->relax_domain_level < c->relax_domain_level)
dattr->relax_domain_level = c->relax_domain_level;
return;
}
static void update_domain_attr_tree(struct sched_domain_attr *dattr,
struct cpuset *root_cs)
{
struct cpuset *cp;
struct cgroup_subsys_state *pos_css;
rcu_read_lock();
cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
/* skip the whole subtree if @cp doesn't have any CPU */
if (cpumask_empty(cp->cpus_allowed)) {
pos_css = css_rightmost_descendant(pos_css);
continue;
}
if (is_sched_load_balance(cp))
update_domain_attr(dattr, cp);
}
rcu_read_unlock();
}
/* Must be called with cpuset_mutex held. */
static inline int nr_cpusets(void)
{
/* jump label reference count + the top-level cpuset */
return static_key_count(&cpusets_enabled_key.key) + 1;
}
/*
* generate_sched_domains()
*
* This function builds a partial partition of the systems CPUs
* A 'partial partition' is a set of non-overlapping subsets whose
* union is a subset of that set.
* The output of this function needs to be passed to kernel/sched/core.c
* partition_sched_domains() routine, which will rebuild the scheduler's
* load balancing domains (sched domains) as specified by that partial
* partition.
*
* See "What is sched_load_balance" in Documentation/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; /* top-down scan of cpusets */
struct cpuset **csa; /* array of all cpuset ptrs */
int csn; /* how many cpuset ptrs in csa so far */
int i, j, k; /* indices for partition finding loops */
cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
struct sched_domain_attr *dattr; /* attributes for custom domains */
int ndoms = 0; /* number of sched domains in result */
int nslot; /* next empty doms[] struct cpumask slot */
struct cgroup_subsys_state *pos_css;
bool root_load_balance = is_sched_load_balance(&top_cpuset);
doms = NULL;
dattr = NULL;
csa = NULL;
/* Special case for the 99% of systems with one, full, sched domain */
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;
/* skip @cp's subtree if not a partition root */
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:
/* Find the best partition (set of sched domains) */
for (i = 0; i < csn; i++) {
struct cpuset *a = csa[i];
int apn = a->pn;
for (j = 0; j < csn; j++) {
struct cpuset *b = csa[j];
int bpn = b->pn;
if (apn != bpn && cpusets_overlap(a, b)) {
for (k = 0; k < csn; k++) {
struct cpuset *c = csa[k];
if (c->pn == bpn)
c->pn = apn;
}
ndoms--; /* one less element */
goto restart;
}
}
}
/*
* Now we know how many domains to create.
* Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
*/
doms = alloc_sched_domains(ndoms);
if (!doms)
goto done;
/*
* The rest of the code, including the scheduler, can deal with
* dattr==NULL case. No need to abort if alloc fails.
*/
dattr = kmalloc_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) {
/* Skip completed partitions */
continue;
}
dp = doms[nslot];
if (nslot == ndoms) {
static int warnings = 10;
if (warnings) {
pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",
nslot, ndoms, csn, i, apn);
warnings--;
}
continue;
}
cpumask_clear(dp);
if (dattr)
*(dattr + nslot) = SD_ATTR_INIT;
for (j = i; j < csn; j++) {
struct cpuset *b = csa[j];
if (apn == b->pn) {
cpumask_or(dp, dp, b->effective_cpus);
cpumask_and(dp, dp, housekeeping_cpumask(HK_FLAG_DOMAIN));
if (dattr)
update_domain_attr_tree(dattr + nslot, b);
/* Done with this partition */
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;
percpu_rwsem_assert_held(&cpuset_rwsem);
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 sched_domain_attr *attr;
cpumask_var_t *doms;
int ndoms;
lockdep_assert_cpus_held();
percpu_rwsem_assert_held(&cpuset_rwsem);
/*
* We have raced with CPU hotplug. Don't do anything to avoid
* passing doms with offlined cpu to partition_sched_domains().
* Anyways, hotplug work item will rebuild sched domains.
*/
if (!top_cpuset.nr_subparts_cpus &&
!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
return;
if (top_cpuset.nr_subparts_cpus &&
!cpumask_subset(top_cpuset.effective_cpus, cpu_active_mask))
return;
/* Generate domain masks and attrs */
ndoms = generate_sched_domains(&doms, &attr);
/* Have scheduler rebuild the domains */
partition_and_rebuild_sched_domains(ndoms, doms, attr);
}
#else /* !CONFIG_SMP */
static void rebuild_sched_domains_locked(void)
{
}
#endif /* CONFIG_SMP */
void rebuild_sched_domains(void)
{
get_online_cpus();
percpu_down_write(&cpuset_rwsem);
rebuild_sched_domains_locked();
percpu_up_write(&cpuset_rwsem);
put_online_cpus();
}
/**
* update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
* @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
*
* Iterate through each task of @cs updating its cpus_allowed to the
* effective cpuset's. As this function is called with cpuset_mutex held,
* cpuset membership stays stable.
*/
static void update_tasks_cpumask(struct cpuset *cs)
{
struct css_task_iter it;
struct task_struct *task;
css_task_iter_start(&cs->css, 0, &it);
while ((task = css_task_iter_next(&it)))
set_cpus_allowed_ptr(task, cs->effective_cpus);
css_task_iter_end(&it);
}
/**
* 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_allowed);
cpumask_and(new_cpus, new_cpus, cpu_active_mask);
} else {
cpumask_and(new_cpus, cs->cpus_allowed, parent->effective_cpus);
}
}
/*
* Commands for update_parent_subparts_cpumask
*/
enum subparts_cmd {
partcmd_enable, /* Enable partition root */
partcmd_disable, /* Disable partition root */
partcmd_update, /* Update parent's subparts_cpus */
};
/**
* 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; /* Moving cpus from effective_cpus to subparts_cpus */
int deleting; /* Moving cpus from subparts_cpus to effective_cpus */
bool part_error = false; /* Partition error? */
percpu_rwsem_assert_held(&cpuset_rwsem);
/*
* 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;
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->effectiveb_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)
cpuset->partition_root_state = PRS_ERROR;
break;
case PRS_ERROR:
if (!part_error)
cpuset->partition_root_state = PRS_ENABLED;
break;
}
/*
* Set part_error if previously in invalid state.
*/
part_error = (prev_prs == PRS_ERROR);
}
if (!part_error && (cpuset->partition_root_state == PRS_ERROR))
return 0; /* Nothing need to be done */
if (cpuset->partition_root_state == 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)
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);
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;
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.
*/
if ((cp != cs) && cp->partition_root_state) {
switch (parent->partition_root_state) {
case PRS_DISABLED:
/*
* If parent is not a partition root or an
* invalid partition root, clear the state
* state and the CS_CPU_EXCLUSIVE flag.
*/
WARN_ON_ONCE(cp->partition_root_state
!= PRS_ERROR);
cp->partition_root_state = 0;
/*
* 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.
*/
cp->partition_root_state = PRS_ERROR;
if (cp->nr_subparts_cpus) {
cp->nr_subparts_cpus = 0;
cpumask_clear(cp->subparts_cpus);
}
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 &&
(cp->partition_root_state != 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);
}
}
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;
/*
* 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;
update_cpumasks_hier(sibling, tmp);
}
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;
/* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
if (cs == &top_cpuset)
return -EACCES;
/*
* An empty cpus_allowed is ok only if the cpuset has no tasks.
* Since cpulist_parse() fails on an empty mask, we special case
* that parsing. The validate_change() call ensures that cpusets
* with tasks have cpus.
*/
if (!*buf) {
cpumask_clear(trialcs->cpus_allowed);
} else {
retval = cpulist_parse(buf, trialcs->cpus_allowed);
if (retval < 0)
return retval;
if (!cpumask_subset(trialcs->cpus_allowed,
top_cpuset.cpus_allowed))
return -EINVAL;
}
/* Nothing to do if the cpus didn't change */
if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
return 0;
retval = validate_change(cs, trialcs);
if (retval < 0)
return retval;
#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) {
/* Cpumask of a partition root cannot be empty */
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);
/*
* Make sure that subparts_cpus is a subset of cpus_allowed.
*/
if (cs->nr_subparts_cpus) {
cpumask_andnot(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);
/* on a wq worker, no need to worry about %current's mems_allowed */
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; /* protected by cpuset_mutex */
struct css_task_iter it;
struct task_struct *task;
cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
guarantee_online_mems(cs, &newmems);
/*
* The mpol_rebind_mm() call takes mmap_sem, 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;
/* We're done rebinding vmas to this cpuset's new mems_allowed. */
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;
/* Skip the whole subtree if the nodemask remains the same. */
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_sem, 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; /* Too easy - nothing to do */
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);
/* use trialcs->mems_allowed as a temp variable */
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
* val: 0 - disabled, 1 - enabled
*
* Call with cpuset_mutex held.
*/
static int update_prstate(struct cpuset *cs, int val)
{
int err;
struct cpuset *parent = parent_cs(cs);
struct tmpmasks tmp;
if ((val != 0) && (val != 1))
return -EINVAL;
if (val == cs->partition_root_state)
return 0;
/*
* Cannot force a partial or invalid partition root to a full
* partition root.
*/
if (val && cs->partition_root_state)
return -EINVAL;
if (alloc_cpumasks(NULL, &tmp))
return -ENOMEM;
err = -EINVAL;
if (!cs->partition_root_state) {
/*
* 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, &tmp);
if (err) {
update_flag(CS_CPU_EXCLUSIVE, cs, 0);
goto out;
}
cs->partition_root_state = PRS_ENABLED;
} else {
/*
* Turning off partition root will clear the
* CS_CPU_EXCLUSIVE bit.
*/
if (cs->partition_root_state == PRS_ERROR) {
cs->partition_root_state = 0;
update_flag(CS_CPU_EXCLUSIVE, cs, 0);
err = 0;
goto out;
}
err = update_parent_subparts_cpumask(cs, partcmd_disable,
NULL, &tmp);
if (err)
goto out;
cs->partition_root_state = 0;
/* Turning off CS_CPU_EXCLUSIVE will not return error */
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, &tmp);
rebuild_sched_domains_locked();
out:
free_cpumasks(NULL, &tmp);
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 /* coefficient for half-life of 10 secs */
#define FM_MAXTICKS ((u32)99) /* useless computing more ticks than this */
#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
#define FM_SCALE 1000 /* faux fixed point scale */
/* Initialize a frequency meter */
static void fmeter_init(struct fmeter *fmp)
{
fmp->cnt = 0;
fmp->val = 0;
fmp->time = 0;
spin_lock_init(&fmp->lock);
}
/* Internal meter update - process cnt events and update value */
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;
}
/* Process any previous ticks, then bump cnt by one (times scale). */
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);
}
/* Process any previous ticks, then return current value. */
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;
/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
static int cpuset_can_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
struct cpuset *cs;
struct task_struct *task;
int ret;
/* used later by cpuset_attach() */
cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
cs = css_cs(css);
percpu_down_write(&cpuset_rwsem);
/* allow moving tasks into an empty cpuset if on default hierarchy */
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->cpus_allowed);
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:
percpu_up_write(&cpuset_rwsem);
return ret;
}
static void cpuset_cancel_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
cgroup_taskset_first(tset, &css);
percpu_down_write(&cpuset_rwsem);
css_cs(css)->attach_in_progress--;
percpu_up_write(&cpuset_rwsem);
}
/*
* 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 buf protected by cpuset_mutex */
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);
percpu_down_write(&cpuset_rwsem);
/* prepare for attach */
if (cs == &top_cpuset)
cpumask_copy(cpus_attach, cpu_possible_mask);
else
guarantee_online_cpus(cs, cpus_attach);
guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
cgroup_taskset_for_each(task, css, tset) {
/*
* can_attach beforehand should guarantee that this doesn't
* fail. TODO: have a better way to handle failure here
*/
WARN_ON_ONCE(set_cpus_allowed_ptr(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);
percpu_up_write(&cpuset_rwsem);
}
/* The various types of files and directories in a cpuset file system */
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();
percpu_down_write(&cpuset_rwsem);
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:
percpu_up_write(&cpuset_rwsem);
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();
percpu_down_write(&cpuset_rwsem);
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:
percpu_up_write(&cpuset_rwsem);
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();
percpu_down_write(&cpuset_rwsem);
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:
percpu_up_write(&cpuset_rwsem);
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_allowed));
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();
}
/* Unreachable but makes gcc happy */
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();
}
/* Unrechable but makes gcc happy */
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;
}
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();
percpu_down_write(&cpuset_rwsem);
if (!is_cpuset_online(cs))
goto out_unlock;
retval = update_prstate(cs, val);
out_unlock:
percpu_up_write(&cpuset_rwsem);
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,
},
{ } /* terminate */
};
/*
* 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,
},
{ } /* terminate */
};
/*
* 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();
percpu_down_write(&cpuset_rwsem);
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->effective_cpus, parent->cpus_allowed);
spin_unlock_irq(&callback_lock);
out_unlock:
percpu_up_write(&cpuset_rwsem);
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();
percpu_down_write(&cpuset_rwsem);
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);
percpu_up_write(&cpuset_rwsem);
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)
{
percpu_down_write(&cpuset_rwsem);
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);
percpu_up_write(&cpuset_rwsem);
}
/*
* 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)
{
if (task_css_is_root(task, cpuset_cgrp_id))
return;
set_cpus_allowed_ptr(task, current->cpus_ptr);
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(percpu_init_rwsem(&cpuset_rwsem));
BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, 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);
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);
percpu_up_write(&cpuset_rwsem);
/*
* 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);
percpu_down_write(&cpuset_rwsem);
}
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;
retry:
wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
percpu_down_write(&cpuset_rwsem);
/*
* 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) {
percpu_up_write(&cpuset_rwsem);
goto retry;
}
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) {
cs->nr_subparts_cpus = 0;
cpumask_clear(cs->subparts_cpus);
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);
cs->partition_root_state = PRS_ERROR;
}
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);
percpu_up_write(&cpuset_rwsem);
}
/**
* 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.
*/
static 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;
percpu_down_write(&cpuset_rwsem);
/* fetch the available cpus/mems and find out which changed how */
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);
/* synchronize cpus_allowed to cpu_active_mask */
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);
/* we don't mess with cpumasks of tasks in top_cpuset */
}
/* synchronize mems_allowed to N_MEMORY */
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);
}
percpu_up_write(&cpuset_rwsem);
/* if cpus or mems changed, we need to propagate to descendants */
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();
}
/* rebuild sched domains if cpus_allowed has changed */
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);
}
/*
* 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)
{
cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
top_cpuset.mems_allowed = node_states[N_MEMORY];
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(task_cs(tsk), pmask);
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
}
/**
* 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)
{
rcu_read_lock();
do_set_cpus_allowed(tsk, is_in_v2_mode() ?
task_cs(tsk)->cpus_allowed : cpu_possible_mask);
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; /* current cpuset ancestors */
int allowed; /* is allocation in zone z 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) /* If hardwall request, stop here */
return false;
if (current->flags & PF_EXITING) /* Let dying task have memory */
return true;
/* Not hardwall and node outside mems_allowed: scan up cpusets */
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(&current->mems_allowed);
return cpuset_spread_node(&current->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(&current->mems_allowed);
return cpuset_spread_node(&current->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(&current->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 /* CONFIG_PROC_PID_CPUSET */
/* Display task mems_allowed in /proc/<pid>/status file. */
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));
}