- 根目录:
- kernel
- cpuset.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/namei.h>
#include <linux/pagemap.h>
#include <linux/proc_fs.h>
#include <linux/rcupdate.h>
#include <linux/sched.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/backing-dev.h>
#include <linux/sort.h>
#include <asm/uaccess.h>
#include <linux/atomic.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/cgroup.h>
/*
* Tracks how many cpusets are currently defined in system.
* When there is only one cpuset (the root cpuset) we can
* short circuit some hooks.
*/
int number_of_cpusets __read_mostly;
/* Forward declare cgroup structures */
struct cgroup_subsys cpuset_subsys;
struct cpuset;
/* See "Frequency meter" comments, below. */
struct fmeter {
int cnt; /* unprocessed events count */
int val; /* most recent output value */
time_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 */
cpumask_var_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */
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;
struct work_struct hotplug_work;
};
/* Retrieve the cpuset for a cgroup */
static inline struct cpuset *cgroup_cs(struct cgroup *cont)
{
return container_of(cgroup_subsys_state(cont, cpuset_subsys_id),
struct cpuset, css);
}
/* Retrieve the cpuset for a task */
static inline struct cpuset *task_cs(struct task_struct *task)
{
return container_of(task_subsys_state(task, cpuset_subsys_id),
struct cpuset, css);
}
static inline struct cpuset *parent_cs(const struct cpuset *cs)
{
struct cgroup *pcgrp = cs->css.cgroup->parent;
if (pcgrp)
return cgroup_cs(pcgrp);
return NULL;
}
#ifdef CONFIG_NUMA
static inline bool task_has_mempolicy(struct task_struct *task)
{
return task->mempolicy;
}
#else
static inline bool task_has_mempolicy(struct task_struct *task)
{
return false;
}
#endif
/* bits in struct cpuset flags field */
typedef enum {
CS_ONLINE,
CS_CPU_EXCLUSIVE,
CS_MEM_EXCLUSIVE,
CS_MEM_HARDWALL,
CS_MEMORY_MIGRATE,
CS_SCHED_LOAD_BALANCE,
CS_SPREAD_PAGE,
CS_SPREAD_SLAB,
} cpuset_flagbits_t;
/* convenient tests for these bits */
static inline bool is_cpuset_online(const struct cpuset *cs)
{
return test_bit(CS_ONLINE, &cs->flags);
}
static inline int is_cpu_exclusive(const struct cpuset *cs)
{
return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
}
static inline int is_mem_exclusive(const struct cpuset *cs)
{
return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
}
static inline int is_mem_hardwall(const struct cpuset *cs)
{
return test_bit(CS_MEM_HARDWALL, &cs->flags);
}
static inline int is_sched_load_balance(const struct cpuset *cs)
{
return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
}
static inline int is_memory_migrate(const struct cpuset *cs)
{
return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
}
static inline int is_spread_page(const struct cpuset *cs)
{
return test_bit(CS_SPREAD_PAGE, &cs->flags);
}
static inline int is_spread_slab(const struct cpuset *cs)
{
return test_bit(CS_SPREAD_SLAB, &cs->flags);
}
static struct cpuset top_cpuset = {
.flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
(1 << CS_MEM_EXCLUSIVE)),
};
/**
* cpuset_for_each_child - traverse online children of a cpuset
* @child_cs: loop cursor pointing to the current child
* @pos_cgrp: used for iteration
* _cs: target cpuset to walk children of
*
* Walk @child_cs through the online children of _cs. Must be used
* with RCU read locked.
*/
#define cpuset_for_each_child(child_cs, pos_cgrp, parent_cs) \
cgroup_for_each_child((pos_cgrp), (parent_cs)->css.cgroup) \
if (is_cpuset_online(((child_cs) = cgroup_cs((pos_cgrp)))))
/**
* cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
* @des_cs: loop cursor pointing to the current descendant
* @pos_cgrp: 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_cgrp by calling
* cgroup_rightmost_descendant() to skip subtree.
*/
#define cpuset_for_each_descendant_pre(des_cs, pos_cgrp, root_cs) \
cgroup_for_each_descendant_pre((pos_cgrp), (root_cs)->css.cgroup) \
if (is_cpuset_online(((des_cs) = cgroup_cs((pos_cgrp)))))
/*
* There are two global mutexes guarding cpuset structures - cpuset_mutex
* and callback_mutex. The latter may nest inside the former. 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 mutexes 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_mutex 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_mutex to query cpusets.
* Once it is ready to make the changes, it takes callback_mutex, blocking
* everyone else.
*
* Calls to the kernel memory allocator can not be made while holding
* callback_mutex, as that would risk double tripping on callback_mutex
* from one of the callbacks into the cpuset code from within
* __alloc_pages().
*
* If a task is only holding callback_mutex, 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_mutex across
* small pieces of code, such as when reading out possibly multi-word
* cpumasks and nodemasks.
*
* Accessing a task's cpuset should be done in accordance with the
* guidelines for accessing subsystem state in kernel/cgroup.c
*/
static DEFINE_MUTEX(cpuset_mutex);
static DEFINE_MUTEX(callback_mutex);
/*
* CPU / memory hotplug is handled asynchronously.
*/
static struct workqueue_struct *cpuset_propagate_hotplug_wq;
static void cpuset_hotplug_workfn(struct work_struct *work);
static void cpuset_propagate_hotplug_workfn(struct work_struct *work);
static void schedule_cpuset_propagate_hotplug(struct cpuset *cs);
static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
/*
* This is ugly, but preserves the userspace API for existing cpuset
* users. If someone tries to mount the "cpuset" filesystem, we
* silently switch it to mount "cgroup" instead
*/
static struct dentry *cpuset_mount(struct file_system_type *fs_type,
int flags, const char *unused_dev_name, void *data)
{
struct file_system_type *cgroup_fs = get_fs_type("cgroup");
struct dentry *ret = ERR_PTR(-ENODEV);
if (cgroup_fs) {
char mountopts[] =
"cpuset,noprefix,"
"release_agent=/sbin/cpuset_release_agent";
ret = cgroup_fs->mount(cgroup_fs, flags,
unused_dev_name, mountopts);
put_filesystem(cgroup_fs);
}
return ret;
}
static struct file_system_type cpuset_fs_type = {
.name = "cpuset",
.mount = cpuset_mount,
};
/*
* Return in pmask the portion of a cpusets's cpus_allowed that
* are online. If none are online, walk up the cpuset hierarchy
* until we find one that does have some online cpus. If we get
* all the way to the top and still haven't found any online cpus,
* return cpu_online_mask. Or if passed a NULL cs from an exit'ing
* task, return cpu_online_mask.
*
* One way or another, we guarantee to return some non-empty subset
* of cpu_online_mask.
*
* Call with callback_mutex held.
*/
static void guarantee_online_cpus(const struct cpuset *cs,
struct cpumask *pmask)
{
while (cs && !cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
cs = parent_cs(cs);
if (cs)
cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
else
cpumask_copy(pmask, cpu_online_mask);
BUG_ON(!cpumask_intersects(pmask, 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. If we get all the way to the top and still haven't
* found any online mems, return node_states[N_MEMORY].
*
* One way or another, we guarantee to return some non-empty subset
* of node_states[N_MEMORY].
*
* Call with callback_mutex held.
*/
static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
{
while (cs && !nodes_intersects(cs->mems_allowed,
node_states[N_MEMORY]))
cs = parent_cs(cs);
if (cs)
nodes_and(*pmask, cs->mems_allowed,
node_states[N_MEMORY]);
else
*pmask = node_states[N_MEMORY];
BUG_ON(!nodes_intersects(*pmask, node_states[N_MEMORY]));
}
/*
* update task's spread flag if cpuset's page/slab spread flag is set
*
* Called with callback_mutex/cpuset_mutex held
*/
static void cpuset_update_task_spread_flag(struct cpuset *cs,
struct task_struct *tsk)
{
if (is_spread_page(cs))
tsk->flags |= PF_SPREAD_PAGE;
else
tsk->flags &= ~PF_SPREAD_PAGE;
if (is_spread_slab(cs))
tsk->flags |= PF_SPREAD_SLAB;
else
tsk->flags &= ~PF_SPREAD_SLAB;
}
/*
* is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
*
* One cpuset is a subset of another if all its allowed CPUs and
* Memory Nodes are a subset of the other, and its exclusive flags
* are only set if the other's are set. Call holding cpuset_mutex.
*/
static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
{
return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
nodes_subset(p->mems_allowed, q->mems_allowed) &&
is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
is_mem_exclusive(p) <= is_mem_exclusive(q);
}
/**
* alloc_trial_cpuset - allocate a trial cpuset
* @cs: the cpuset that the trial cpuset duplicates
*/
static struct cpuset *alloc_trial_cpuset(const struct cpuset *cs)
{
struct cpuset *trial;
trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
if (!trial)
return NULL;
if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL)) {
kfree(trial);
return NULL;
}
cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
return trial;
}
/**
* free_trial_cpuset - free the trial cpuset
* @trial: the trial cpuset to be freed
*/
static void free_trial_cpuset(struct cpuset *trial)
{
free_cpumask_var(trial->cpus_allowed);
kfree(trial);
}
/*
* validate_change() - Used to validate that any proposed cpuset change
* follows the structural rules for cpusets.
*
* If we replaced the flag and mask values of the current cpuset
* (cur) with those values in the trial cpuset (trial), would
* our various subset and exclusive rules still be valid? Presumes
* cpuset_mutex held.
*
* 'cur' is the address of an actual, in-use cpuset. Operations
* such as list traversal that depend on the actual address of the
* cpuset in the list must use cur below, not trial.
*
* 'trial' is the address of bulk structure copy of cur, with
* perhaps one or more of the fields cpus_allowed, mems_allowed,
* or flags changed to new, trial values.
*
* Return 0 if valid, -errno if not.
*/
static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
{
struct cgroup *cont;
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, cont, 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);
/* We must be a subset of our parent cpuset */
ret = -EACCES;
if (!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, cont, 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
* have empty cpus_allowed or mems_allowed.
*/
ret = -ENOSPC;
if ((cgroup_task_count(cur->css.cgroup) || cur->attach_in_progress) &&
(cpumask_empty(trial->cpus_allowed) ||
nodes_empty(trial->mems_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 cpus_allowed masks?
*/
static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
{
return cpumask_intersects(a->cpus_allowed, b->cpus_allowed);
}
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 *pos_cgrp;
rcu_read_lock();
cpuset_for_each_descendant_pre(cp, pos_cgrp, root_cs) {
/* skip the whole subtree if @cp doesn't have any CPU */
if (cpumask_empty(cp->cpus_allowed)) {
pos_cgrp = cgroup_rightmost_descendant(pos_cgrp);
continue;
}
if (is_sched_load_balance(cp))
update_domain_attr(dattr, cp);
}
rcu_read_unlock();
}
/*
* 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.c
* partition_sched_domains() routine, which will rebuild the scheduler's
* load balancing domains (sched domains) as specified by that partial
* partition.
*
* See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
* for a background explanation of this.
*
* Does not return errors, on the theory that the callers of this
* routine would rather not worry about failures to rebuild sched
* domains when operating in the severe memory shortage situations
* that could cause allocation failures below.
*
* Must be called with cpuset_mutex held.
*
* The three key local variables below are:
* q - a linked-list queue of cpuset pointers, used to implement a
* top-down scan of all cpusets. This scan loads a pointer
* to each cpuset marked is_sched_load_balance into the
* array 'csa'. For our purposes, rebuilding the schedulers
* sched domains, we can ignore !is_sched_load_balance cpusets.
* csa - (for CpuSet Array) Array of pointers to all the cpusets
* that need to be load balanced, for convenient iterative
* access by the subsequent code that finds the best partition,
* i.e the set of domains (subsets) of CPUs such that the
* cpus_allowed of every cpuset marked is_sched_load_balance
* is a subset of one of these domains, while there are as
* many such domains as possible, each as small as possible.
* doms - Conversion of 'csa' to an array of cpumasks, for passing to
* the kernel/sched.c routine partition_sched_domains() in a
* convenient format, that can be easily compared to the prior
* value to determine what partition elements (sched domains)
* were changed (added or removed.)
*
* Finding the best partition (set of domains):
* The triple nested loops below over i, j, k scan over the
* load balanced cpusets (using the array of cpuset pointers in
* csa[]) looking for pairs of cpusets that have overlapping
* cpus_allowed, but which don't have the same 'pn' partition
* number and gives them in the same partition number. It keeps
* looping on the 'restart' label until it can no longer find
* any such pairs.
*
* The union of the cpus_allowed masks from the set of
* all cpusets having the same 'pn' value then form the one
* element of the partition (one sched domain) to be passed to
* partition_sched_domains().
*/
static int generate_sched_domains(cpumask_var_t **domains,
struct sched_domain_attr **attributes)
{
struct cpuset *cp; /* scans q */
struct cpuset **csa; /* array of all cpuset ptrs */
int csn; /* how many cpuset ptrs in csa so far */
int i, j, k; /* indices for partition finding loops */
cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
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 *pos_cgrp;
doms = NULL;
dattr = NULL;
csa = NULL;
/* Special case for the 99% of systems with one, full, sched domain */
if (is_sched_load_balance(&top_cpuset)) {
ndoms = 1;
doms = alloc_sched_domains(ndoms);
if (!doms)
goto done;
dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
if (dattr) {
*dattr = SD_ATTR_INIT;
update_domain_attr_tree(dattr, &top_cpuset);
}
cpumask_copy(doms[0], top_cpuset.cpus_allowed);
goto done;
}
csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
if (!csa)
goto done;
csn = 0;
rcu_read_lock();
cpuset_for_each_descendant_pre(cp, pos_cgrp, &top_cpuset) {
/*
* Continue traversing beyond @cp iff @cp has some CPUs and
* isn't load balancing. The former is obvious. The
* latter: All child cpusets contain a subset of the
* parent's cpus, so just skip them, and then we call
* update_domain_attr_tree() to calc relax_domain_level of
* the corresponding sched domain.
*/
if (!cpumask_empty(cp->cpus_allowed) &&
!is_sched_load_balance(cp))
continue;
if (is_sched_load_balance(cp))
csa[csn++] = cp;
/* skip @cp's subtree */
pos_cgrp = cgroup_rightmost_descendant(pos_cgrp);
}
rcu_read_unlock();
for (i = 0; i < csn; i++)
csa[i]->pn = i;
ndoms = csn;
restart:
/* Find the best partition (set of sched domains) */
for (i = 0; i < csn; i++) {
struct cpuset *a = csa[i];
int apn = a->pn;
for (j = 0; j < csn; j++) {
struct cpuset *b = csa[j];
int bpn = b->pn;
if (apn != bpn && cpusets_overlap(a, b)) {
for (k = 0; k < csn; k++) {
struct cpuset *c = csa[k];
if (c->pn == bpn)
c->pn = apn;
}
ndoms--; /* one less element */
goto restart;
}
}
}
/*
* Now we know how many domains to create.
* Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
*/
doms = alloc_sched_domains(ndoms);
if (!doms)
goto done;
/*
* The rest of the code, including the scheduler, can deal with
* dattr==NULL case. No need to abort if alloc fails.
*/
dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
for (nslot = 0, i = 0; i < csn; i++) {
struct cpuset *a = csa[i];
struct cpumask *dp;
int apn = a->pn;
if (apn < 0) {
/* Skip completed partitions */
continue;
}
dp = doms[nslot];
if (nslot == ndoms) {
static int warnings = 10;
if (warnings) {
printk(KERN_WARNING
"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->cpus_allowed);
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;
}
/*
* Rebuild scheduler domains.
*
* If the flag 'sched_load_balance' of any cpuset with non-empty
* 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
* which has that flag enabled, or if any cpuset with a non-empty
* 'cpus' is removed, then call this routine to rebuild the
* scheduler's dynamic sched domains.
*
* Call with cpuset_mutex held. Takes get_online_cpus().
*/
static void rebuild_sched_domains_locked(void)
{
struct sched_domain_attr *attr;
cpumask_var_t *doms;
int ndoms;
lockdep_assert_held(&cpuset_mutex);
get_online_cpus();
/*
* We have raced with CPU hotplug. Don't do anything to avoid
* passing doms with offlined cpu to partition_sched_domains().
* Anyways, hotplug work item will rebuild sched domains.
*/
if (!cpumask_equal(top_cpuset.cpus_allowed, cpu_active_mask))
goto out;
/* Generate domain masks and attrs */
ndoms = generate_sched_domains(&doms, &attr);
/* Have scheduler rebuild the domains */
partition_sched_domains(ndoms, doms, attr);
out:
put_online_cpus();
}
#else /* !CONFIG_SMP */
static void rebuild_sched_domains_locked(void)
{
}
#endif /* CONFIG_SMP */
void rebuild_sched_domains(void)
{
mutex_lock(&cpuset_mutex);
rebuild_sched_domains_locked();
mutex_unlock(&cpuset_mutex);
}
/**
* cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's
* @tsk: task to test
* @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
*
* Call with cpuset_mutex held. May take callback_mutex during call.
* Called for each task in a cgroup by cgroup_scan_tasks().
* Return nonzero if this tasks's cpus_allowed mask should be changed (in other
* words, if its mask is not equal to its cpuset's mask).
*/
static int cpuset_test_cpumask(struct task_struct *tsk,
struct cgroup_scanner *scan)
{
return !cpumask_equal(&tsk->cpus_allowed,
(cgroup_cs(scan->cg))->cpus_allowed);
}
/**
* cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
* @tsk: task to test
* @scan: struct cgroup_scanner containing the cgroup of the task
*
* Called by cgroup_scan_tasks() for each task in a cgroup whose
* cpus_allowed mask needs to be changed.
*
* We don't need to re-check for the cgroup/cpuset membership, since we're
* holding cpuset_mutex at this point.
*/
static void cpuset_change_cpumask(struct task_struct *tsk,
struct cgroup_scanner *scan)
{
set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed));
}
/**
* 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
* @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
*
* Called with cpuset_mutex held
*
* The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
* calling callback functions for each.
*
* No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
* if @heap != NULL.
*/
static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
{
struct cgroup_scanner scan;
scan.cg = cs->css.cgroup;
scan.test_task = cpuset_test_cpumask;
scan.process_task = cpuset_change_cpumask;
scan.heap = heap;
cgroup_scan_tasks(&scan);
}
/**
* update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
* @cs: the cpuset to consider
* @buf: buffer of cpu numbers written to this cpuset
*/
static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
const char *buf)
{
struct ptr_heap heap;
int retval;
int is_load_balanced;
/* 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, cpu_active_mask))
return -EINVAL;
}
retval = validate_change(cs, trialcs);
if (retval < 0)
return retval;
/* Nothing to do if the cpus didn't change */
if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
return 0;
retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
if (retval)
return retval;
is_load_balanced = is_sched_load_balance(trialcs);
mutex_lock(&callback_mutex);
cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
mutex_unlock(&callback_mutex);
/*
* Scan tasks in the cpuset, and update the cpumasks of any
* that need an update.
*/
update_tasks_cpumask(cs, &heap);
heap_free(&heap);
if (is_load_balanced)
rebuild_sched_domains_locked();
return 0;
}
/*
* cpuset_migrate_mm
*
* Migrate memory region from one set of nodes to another.
*
* Temporarilly set tasks mems_allowed to target nodes of migration,
* so that the migration code can allocate pages on these nodes.
*
* Call holding cpuset_mutex, so current's cpuset won't change
* during this call, as manage_mutex holds off any cpuset_attach()
* calls. Therefore we don't need to take task_lock around the
* call to guarantee_online_mems(), as we know no one is changing
* our task's cpuset.
*
* While the mm_struct we are migrating is typically from some
* other task, the task_struct mems_allowed that we are hacking
* is for our current task, which must allocate new pages for that
* migrating memory region.
*/
static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
const nodemask_t *to)
{
struct task_struct *tsk = current;
tsk->mems_allowed = *to;
do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
}
/*
* 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
*
* In order to avoid seeing no nodes if the old and new nodes are disjoint,
* we structure updates as setting all new allowed nodes, then clearing newly
* disallowed ones.
*/
static void cpuset_change_task_nodemask(struct task_struct *tsk,
nodemask_t *newmems)
{
bool need_loop;
/*
* Allow tasks that have access to memory reserves because they have
* been OOM killed to get memory anywhere.
*/
if (unlikely(test_thread_flag(TIF_MEMDIE)))
return;
if (current->flags & PF_EXITING) /* Let dying task have memory */
return;
task_lock(tsk);
/*
* Determine if a loop is necessary if another thread is doing
* get_mems_allowed(). If at least one node remains unchanged and
* tsk does not have a mempolicy, then an empty nodemask will not be
* possible when mems_allowed is larger than a word.
*/
need_loop = task_has_mempolicy(tsk) ||
!nodes_intersects(*newmems, tsk->mems_allowed);
if (need_loop)
write_seqcount_begin(&tsk->mems_allowed_seq);
nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
tsk->mems_allowed = *newmems;
if (need_loop)
write_seqcount_end(&tsk->mems_allowed_seq);
task_unlock(tsk);
}
/*
* Update task's mems_allowed and rebind its mempolicy and vmas' mempolicy
* of it to cpuset's new mems_allowed, and migrate pages to new nodes if
* memory_migrate flag is set. Called with cpuset_mutex held.
*/
static void cpuset_change_nodemask(struct task_struct *p,
struct cgroup_scanner *scan)
{
struct mm_struct *mm;
struct cpuset *cs;
int migrate;
const nodemask_t *oldmem = scan->data;
static nodemask_t newmems; /* protected by cpuset_mutex */
cs = cgroup_cs(scan->cg);
guarantee_online_mems(cs, &newmems);
cpuset_change_task_nodemask(p, &newmems);
mm = get_task_mm(p);
if (!mm)
return;
migrate = is_memory_migrate(cs);
mpol_rebind_mm(mm, &cs->mems_allowed);
if (migrate)
cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
mmput(mm);
}
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
* @oldmem: old mems_allowed of cpuset cs
* @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
*
* Called with cpuset_mutex held
* No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
* if @heap != NULL.
*/
static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
struct ptr_heap *heap)
{
struct cgroup_scanner scan;
cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
scan.cg = cs->css.cgroup;
scan.test_task = NULL;
scan.process_task = cpuset_change_nodemask;
scan.heap = heap;
scan.data = (nodemask_t *)oldmem;
/*
* 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.
*/
cgroup_scan_tasks(&scan);
/* We're done rebinding vmas to this cpuset's new mems_allowed. */
cpuset_being_rebound = NULL;
}
/*
* 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_mutex 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)
{
NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL);
int retval;
struct ptr_heap heap;
if (!oldmem)
return -ENOMEM;
/*
* 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,
node_states[N_MEMORY])) {
retval = -EINVAL;
goto done;
}
}
*oldmem = cs->mems_allowed;
if (nodes_equal(*oldmem, trialcs->mems_allowed)) {
retval = 0; /* Too easy - nothing to do */
goto done;
}
retval = validate_change(cs, trialcs);
if (retval < 0)
goto done;
retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
if (retval < 0)
goto done;
mutex_lock(&callback_mutex);
cs->mems_allowed = trialcs->mems_allowed;
mutex_unlock(&callback_mutex);
update_tasks_nodemask(cs, oldmem, &heap);
heap_free(&heap);
done:
NODEMASK_FREE(oldmem);
return retval;
}
int current_cpuset_is_being_rebound(void)
{
return task_cs(current) == cpuset_being_rebound;
}
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;
}
/*
* cpuset_change_flag - make a task's spread flags the same as its cpuset's
* @tsk: task to be updated
* @scan: struct cgroup_scanner containing the cgroup of the task
*
* Called by cgroup_scan_tasks() for each task in a cgroup.
*
* We don't need to re-check for the cgroup/cpuset membership, since we're
* holding cpuset_mutex at this point.
*/
static void cpuset_change_flag(struct task_struct *tsk,
struct cgroup_scanner *scan)
{
cpuset_update_task_spread_flag(cgroup_cs(scan->cg), tsk);
}
/*
* 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
* @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
*
* Called with cpuset_mutex held
*
* The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
* calling callback functions for each.
*
* No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
* if @heap != NULL.
*/
static void update_tasks_flags(struct cpuset *cs, struct ptr_heap *heap)
{
struct cgroup_scanner scan;
scan.cg = cs->css.cgroup;
scan.test_task = NULL;
scan.process_task = cpuset_change_flag;
scan.heap = heap;
cgroup_scan_tasks(&scan);
}
/*
* 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;
struct ptr_heap heap;
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;
err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
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)));
mutex_lock(&callback_mutex);
cs->flags = trialcs->flags;
mutex_unlock(&callback_mutex);
if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
rebuild_sched_domains_locked();
if (spread_flag_changed)
update_tasks_flags(cs, &heap);
heap_free(&heap);
out:
free_trial_cpuset(trialcs);
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 ((time_t)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)
{
time_t now = get_seconds();
time_t 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;
}
/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
{
struct cpuset *cs = cgroup_cs(cgrp);
struct task_struct *task;
int ret;
mutex_lock(&cpuset_mutex);
ret = -ENOSPC;
if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
goto out_unlock;
cgroup_taskset_for_each(task, cgrp, tset) {
/*
* Kthreads which disallow setaffinity shouldn't be moved
* to a new cpuset; we don't want to change their cpu
* affinity and isolating such threads by their set of
* allowed nodes is unnecessary. Thus, cpusets are not
* applicable for such threads. This prevents checking for
* success of set_cpus_allowed_ptr() on all attached tasks
* before cpus_allowed may be changed.
*/
ret = -EINVAL;
if (task->flags & PF_NO_SETAFFINITY)
goto out_unlock;
ret = security_task_setscheduler(task);
if (ret)
goto out_unlock;
}
/*
* Mark attach is in progress. This makes validate_change() fail
* changes which zero cpus/mems_allowed.
*/
cs->attach_in_progress++;
ret = 0;
out_unlock:
mutex_unlock(&cpuset_mutex);
return ret;
}
static void cpuset_cancel_attach(struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
mutex_lock(&cpuset_mutex);
cgroup_cs(cgrp)->attach_in_progress--;
mutex_unlock(&cpuset_mutex);
}
/*
* Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach()
* but we can't allocate it dynamically there. Define it global and
* allocate from cpuset_init().
*/
static cpumask_var_t cpus_attach;
static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
{
/* static bufs protected by cpuset_mutex */
static nodemask_t cpuset_attach_nodemask_from;
static nodemask_t cpuset_attach_nodemask_to;
struct mm_struct *mm;
struct task_struct *task;
struct task_struct *leader = cgroup_taskset_first(tset);
struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
struct cpuset *cs = cgroup_cs(cgrp);
struct cpuset *oldcs = cgroup_cs(oldcgrp);
mutex_lock(&cpuset_mutex);
/* 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, cgrp, 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, possibly for multiple threads in a threadgroup. This is
* expensive and may sleep.
*/
cpuset_attach_nodemask_from = oldcs->mems_allowed;
cpuset_attach_nodemask_to = cs->mems_allowed;
mm = get_task_mm(leader);
if (mm) {
mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
if (is_memory_migrate(cs))
cpuset_migrate_mm(mm, &cpuset_attach_nodemask_from,
&cpuset_attach_nodemask_to);
mmput(mm);
}
cs->attach_in_progress--;
/*
* We may have raced with CPU/memory hotunplug. Trigger hotplug
* propagation if @cs doesn't have any CPU or memory. It will move
* the newly added tasks to the nearest parent which can execute.
*/
if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
schedule_cpuset_propagate_hotplug(cs);
mutex_unlock(&cpuset_mutex);
}
/* The various types of files and directories in a cpuset file system */
typedef enum {
FILE_MEMORY_MIGRATE,
FILE_CPULIST,
FILE_MEMLIST,
FILE_CPU_EXCLUSIVE,
FILE_MEM_EXCLUSIVE,
FILE_MEM_HARDWALL,
FILE_SCHED_LOAD_BALANCE,
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 *cgrp, struct cftype *cft, u64 val)
{
struct cpuset *cs = cgroup_cs(cgrp);
cpuset_filetype_t type = cft->private;
int retval = -ENODEV;
mutex_lock(&cpuset_mutex);
if (!is_cpuset_online(cs))
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_MEMORY_PRESSURE:
retval = -EACCES;
break;
case FILE_SPREAD_PAGE:
retval = update_flag(CS_SPREAD_PAGE, cs, val);
break;
case FILE_SPREAD_SLAB:
retval = update_flag(CS_SPREAD_SLAB, cs, val);
break;
default:
retval = -EINVAL;
break;
}
out_unlock:
mutex_unlock(&cpuset_mutex);
return retval;
}
static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
{
struct cpuset *cs = cgroup_cs(cgrp);
cpuset_filetype_t type = cft->private;
int retval = -ENODEV;
mutex_lock(&cpuset_mutex);
if (!is_cpuset_online(cs))
goto out_unlock;
switch (type) {
case FILE_SCHED_RELAX_DOMAIN_LEVEL:
retval = update_relax_domain_level(cs, val);
break;
default:
retval = -EINVAL;
break;
}
out_unlock:
mutex_unlock(&cpuset_mutex);
return retval;
}
/*
* Common handling for a write to a "cpus" or "mems" file.
*/
static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
const char *buf)
{
struct cpuset *cs = cgroup_cs(cgrp);
struct cpuset *trialcs;
int retval = -ENODEV;
/*
* 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.
*
* Flushing cpuset_hotplug_work is enough to synchronize against
* hotplug hanlding; however, cpuset_attach() may schedule
* propagation work directly. Flush the workqueue too.
*/
flush_work(&cpuset_hotplug_work);
flush_workqueue(cpuset_propagate_hotplug_wq);
mutex_lock(&cpuset_mutex);
if (!is_cpuset_online(cs))
goto out_unlock;
trialcs = alloc_trial_cpuset(cs);
if (!trialcs) {
retval = -ENOMEM;
goto out_unlock;
}
switch (cft->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_trial_cpuset(trialcs);
out_unlock:
mutex_unlock(&cpuset_mutex);
return retval;
}
/*
* 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.
* A single large read to a buffer that crosses a page boundary is
* ok, because the result being copied to user land is not recomputed
* across a page fault.
*/
static size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
{
size_t count;
mutex_lock(&callback_mutex);
count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed);
mutex_unlock(&callback_mutex);
return count;
}
static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs)
{
size_t count;
mutex_lock(&callback_mutex);
count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed);
mutex_unlock(&callback_mutex);
return count;
}
static ssize_t cpuset_common_file_read(struct cgroup *cont,
struct cftype *cft,
struct file *file,
char __user *buf,
size_t nbytes, loff_t *ppos)
{
struct cpuset *cs = cgroup_cs(cont);
cpuset_filetype_t type = cft->private;
char *page;
ssize_t retval = 0;
char *s;
if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
return -ENOMEM;
s = page;
switch (type) {
case FILE_CPULIST:
s += cpuset_sprintf_cpulist(s, cs);
break;
case FILE_MEMLIST:
s += cpuset_sprintf_memlist(s, cs);
break;
default:
retval = -EINVAL;
goto out;
}
*s++ = '\n';
retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
out:
free_page((unsigned long)page);
return retval;
}
static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft)
{
struct cpuset *cs = cgroup_cs(cont);
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 *cont, struct cftype *cft)
{
struct cpuset *cs = cgroup_cs(cont);
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;
}
/*
* for the common functions, 'private' gives the type of file
*/
static struct cftype files[] = {
{
.name = "cpus",
.read = cpuset_common_file_read,
.write_string = cpuset_write_resmask,
.max_write_len = (100U + 6 * NR_CPUS),
.private = FILE_CPULIST,
},
{
.name = "mems",
.read = cpuset_common_file_read,
.write_string = cpuset_write_resmask,
.max_write_len = (100U + 6 * MAX_NUMNODES),
.private = FILE_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,
.write_u64 = cpuset_write_u64,
.private = FILE_MEMORY_PRESSURE,
.mode = S_IRUGO,
},
{
.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 */
};
/*
* cpuset_css_alloc - allocate a cpuset css
* cont: control group that the new cpuset will be part of
*/
static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
{
struct cpuset *cs;
if (!cont->parent)
return &top_cpuset.css;
cs = kzalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return ERR_PTR(-ENOMEM);
if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
kfree(cs);
return ERR_PTR(-ENOMEM);
}
set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
cpumask_clear(cs->cpus_allowed);
nodes_clear(cs->mems_allowed);
fmeter_init(&cs->fmeter);
INIT_WORK(&cs->hotplug_work, cpuset_propagate_hotplug_workfn);
cs->relax_domain_level = -1;
return &cs->css;
}
static int cpuset_css_online(struct cgroup *cgrp)
{
struct cpuset *cs = cgroup_cs(cgrp);
struct cpuset *parent = parent_cs(cs);
struct cpuset *tmp_cs;
struct cgroup *pos_cg;
if (!parent)
return 0;
mutex_lock(&cpuset_mutex);
set_bit(CS_ONLINE, &cs->flags);
if (is_spread_page(parent))
set_bit(CS_SPREAD_PAGE, &cs->flags);
if (is_spread_slab(parent))
set_bit(CS_SPREAD_SLAB, &cs->flags);
number_of_cpusets++;
if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags))
goto out_unlock;
/*
* Clone '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_cg, parent) {
if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
rcu_read_unlock();
goto out_unlock;
}
}
rcu_read_unlock();
mutex_lock(&callback_mutex);
cs->mems_allowed = parent->mems_allowed;
cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
mutex_unlock(&callback_mutex);
out_unlock:
mutex_unlock(&cpuset_mutex);
return 0;
}
static void cpuset_css_offline(struct cgroup *cgrp)
{
struct cpuset *cs = cgroup_cs(cgrp);
mutex_lock(&cpuset_mutex);
if (is_sched_load_balance(cs))
update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
number_of_cpusets--;
clear_bit(CS_ONLINE, &cs->flags);
mutex_unlock(&cpuset_mutex);
}
/*
* 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().
*/
static void cpuset_css_free(struct cgroup *cont)
{
struct cpuset *cs = cgroup_cs(cont);
free_cpumask_var(cs->cpus_allowed);
kfree(cs);
}
struct cgroup_subsys cpuset_subsys = {
.name = "cpuset",
.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,
.subsys_id = cpuset_subsys_id,
.base_cftypes = files,
.early_init = 1,
};
/**
* cpuset_init - initialize cpusets at system boot
*
* Description: Initialize top_cpuset and the cpuset internal file system,
**/
int __init cpuset_init(void)
{
int err = 0;
if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
BUG();
cpumask_setall(top_cpuset.cpus_allowed);
nodes_setall(top_cpuset.mems_allowed);
fmeter_init(&top_cpuset.fmeter);
set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
top_cpuset.relax_domain_level = -1;
err = register_filesystem(&cpuset_fs_type);
if (err < 0)
return err;
if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
BUG();
number_of_cpusets = 1;
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)) {
rcu_read_lock();
printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset %s\n",
cgroup_name(cs->css.cgroup));
rcu_read_unlock();
}
}
/**
* cpuset_propagate_hotplug_workfn - propagate CPU/memory hotplug to a cpuset
* @cs: cpuset in interest
*
* 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_propagate_hotplug_workfn(struct work_struct *work)
{
static cpumask_t off_cpus;
static nodemask_t off_mems, tmp_mems;
struct cpuset *cs = container_of(work, struct cpuset, hotplug_work);
bool is_empty;
mutex_lock(&cpuset_mutex);
cpumask_andnot(&off_cpus, cs->cpus_allowed, top_cpuset.cpus_allowed);
nodes_andnot(off_mems, cs->mems_allowed, top_cpuset.mems_allowed);
/* remove offline cpus from @cs */
if (!cpumask_empty(&off_cpus)) {
mutex_lock(&callback_mutex);
cpumask_andnot(cs->cpus_allowed, cs->cpus_allowed, &off_cpus);
mutex_unlock(&callback_mutex);
update_tasks_cpumask(cs, NULL);
}
/* remove offline mems from @cs */
if (!nodes_empty(off_mems)) {
tmp_mems = cs->mems_allowed;
mutex_lock(&callback_mutex);
nodes_andnot(cs->mems_allowed, cs->mems_allowed, off_mems);
mutex_unlock(&callback_mutex);
update_tasks_nodemask(cs, &tmp_mems, NULL);
}
is_empty = cpumask_empty(cs->cpus_allowed) ||
nodes_empty(cs->mems_allowed);
mutex_unlock(&cpuset_mutex);
/*
* If @cs became empty, 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);
/* the following may free @cs, should be the last operation */
css_put(&cs->css);
}
/**
* schedule_cpuset_propagate_hotplug - schedule hotplug propagation to a cpuset
* @cs: cpuset of interest
*
* Schedule cpuset_propagate_hotplug_workfn() which will update CPU and
* memory masks according to top_cpuset.
*/
static void schedule_cpuset_propagate_hotplug(struct cpuset *cs)
{
/*
* Pin @cs. The refcnt will be released when the work item
* finishes executing.
*/
if (!css_tryget(&cs->css))
return;
/*
* Queue @cs->hotplug_work. If already pending, lose the css ref.
* cpuset_propagate_hotplug_wq is ordered and propagation will
* happen in the order this function is called.
*/
if (!queue_work(cpuset_propagate_hotplug_wq, &cs->hotplug_work))
css_put(&cs->css);
}
/**
* 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_propagate_hotplug() 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, tmp_cpus;
static nodemask_t new_mems, tmp_mems;
bool cpus_updated, mems_updated;
bool cpus_offlined, mems_offlined;
mutex_lock(&cpuset_mutex);
/* fetch the available cpus/mems and find out which changed how */
cpumask_copy(&new_cpus, cpu_active_mask);
new_mems = node_states[N_MEMORY];
cpus_updated = !cpumask_equal(top_cpuset.cpus_allowed, &new_cpus);
cpus_offlined = cpumask_andnot(&tmp_cpus, top_cpuset.cpus_allowed,
&new_cpus);
mems_updated = !nodes_equal(top_cpuset.mems_allowed, new_mems);
nodes_andnot(tmp_mems, top_cpuset.mems_allowed, new_mems);
mems_offlined = !nodes_empty(tmp_mems);
/* synchronize cpus_allowed to cpu_active_mask */
if (cpus_updated) {
mutex_lock(&callback_mutex);
cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
mutex_unlock(&callback_mutex);
/* we don't mess with cpumasks of tasks in top_cpuset */
}
/* synchronize mems_allowed to N_MEMORY */
if (mems_updated) {
tmp_mems = top_cpuset.mems_allowed;
mutex_lock(&callback_mutex);
top_cpuset.mems_allowed = new_mems;
mutex_unlock(&callback_mutex);
update_tasks_nodemask(&top_cpuset, &tmp_mems, NULL);
}
/* if cpus or mems went down, we need to propagate to descendants */
if (cpus_offlined || mems_offlined) {
struct cpuset *cs;
struct cgroup *pos_cgrp;
rcu_read_lock();
cpuset_for_each_descendant_pre(cs, pos_cgrp, &top_cpuset)
schedule_cpuset_propagate_hotplug(cs);
rcu_read_unlock();
}
mutex_unlock(&cpuset_mutex);
/* wait for propagations to finish */
flush_workqueue(cpuset_propagate_hotplug_wq);
/* rebuild sched domains if cpus_allowed has changed */
if (cpus_updated)
rebuild_sched_domains();
}
void cpuset_update_active_cpus(bool cpu_online)
{
/*
* 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.
*
* We still need to do partition_sched_domains() synchronously;
* otherwise, the scheduler will get confused and put tasks to the
* dead CPU. Fall back to the default single domain.
* cpuset_hotplug_workfn() will rebuild it as necessary.
*/
partition_sched_domains(1, NULL, NULL);
schedule_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];
register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
cpuset_propagate_hotplug_wq =
alloc_ordered_workqueue("cpuset_hotplug", 0);
BUG_ON(!cpuset_propagate_hotplug_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)
{
mutex_lock(&callback_mutex);
task_lock(tsk);
guarantee_online_cpus(task_cs(tsk), pmask);
task_unlock(tsk);
mutex_unlock(&callback_mutex);
}
void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
{
const struct cpuset *cs;
rcu_read_lock();
cs = task_cs(tsk);
if (cs)
do_set_cpus_allowed(tsk, cs->cpus_allowed);
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 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;
mutex_lock(&callback_mutex);
task_lock(tsk);
guarantee_online_mems(task_cs(tsk), &mask);
task_unlock(tsk);
mutex_unlock(&callback_mutex);
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_mutex. If no ancestor is mem_exclusive or mem_hardwall
* (an unusual configuration), then returns the root cpuset.
*/
static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
{
while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
cs = parent_cs(cs);
return cs;
}
/**
* cpuset_node_allowed_softwall - 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 __GFP_THISNODE is
* set, yes, we can always allocate. If node is in our task's mems_allowed,
* yes. If it's not a __GFP_HARDWALL request and this node is in the nearest
* hardwalled cpuset ancestor to this task's cpuset, yes. If the task has been
* OOM killed and has access to memory reserves as specified by the TIF_MEMDIE
* flag, yes.
* Otherwise, no.
*
* If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to
* cpuset_node_allowed_hardwall(). Otherwise, cpuset_node_allowed_softwall()
* might sleep, and might allow a node from an enclosing cpuset.
*
* cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
* cpusets, and never sleeps.
*
* The __GFP_THISNODE placement logic is really handled elsewhere,
* by forcibly using a zonelist starting at a specified node, and by
* (in get_page_from_freelist()) refusing to consider the zones for
* any node on the zonelist except the first. By the time any such
* calls get to this routine, we should just shut up and say 'yes'.
*
* 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 as is marked TIF_MEMDIE.
* GFP_KERNEL allocations are not so marked, so can escape to the
* nearest enclosing hardwalled ancestor cpuset.
*
* Scanning up parent cpusets requires callback_mutex. 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_mutex
* mutex.
*
* 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
* TIF_MEMDIE - any node ok
* GFP_KERNEL - any node in enclosing hardwalled cpuset ok
* GFP_USER - only nodes in current tasks mems allowed ok.
*
* Rule:
* Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
* pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
* the code that might scan up ancestor cpusets and sleep.
*/
int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
{
const struct cpuset *cs; /* current cpuset ancestors */
int allowed; /* is allocation in zone z allowed? */
if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
return 1;
might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
if (node_isset(node, current->mems_allowed))
return 1;
/*
* Allow tasks that have access to memory reserves because they have
* been OOM killed to get memory anywhere.
*/
if (unlikely(test_thread_flag(TIF_MEMDIE)))
return 1;
if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
return 0;
if (current->flags & PF_EXITING) /* Let dying task have memory */
return 1;
/* Not hardwall and node outside mems_allowed: scan up cpusets */
mutex_lock(&callback_mutex);
task_lock(current);
cs = nearest_hardwall_ancestor(task_cs(current));
task_unlock(current);
allowed = node_isset(node, cs->mems_allowed);
mutex_unlock(&callback_mutex);
return allowed;
}
/*
* cpuset_node_allowed_hardwall - 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 __GFP_THISNODE is
* set, yes, we can always allocate. If node is in our task's mems_allowed,
* yes. If the task has been OOM killed and has access to memory reserves as
* specified by the TIF_MEMDIE flag, yes.
* Otherwise, no.
*
* The __GFP_THISNODE placement logic is really handled elsewhere,
* by forcibly using a zonelist starting at a specified node, and by
* (in get_page_from_freelist()) refusing to consider the zones for
* any node on the zonelist except the first. By the time any such
* calls get to this routine, we should just shut up and say 'yes'.
*
* Unlike the cpuset_node_allowed_softwall() variant, above,
* this variant requires that the node be in the current task's
* mems_allowed or that we're in interrupt. It does not scan up the
* cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
* It never sleeps.
*/
int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
{
if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
return 1;
if (node_isset(node, current->mems_allowed))
return 1;
/*
* Allow tasks that have access to memory reserves because they have
* been OOM killed to get memory anywhere.
*/
if (unlikely(test_thread_flag(TIF_MEMDIE)))
return 1;
return 0;
}
/**
* 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)
{
int node;
node = next_node(*rotor, current->mems_allowed);
if (node == MAX_NUMNODES)
node = first_node(current->mems_allowed);
*rotor = node;
return node;
}
int cpuset_mem_spread_node(void)
{
if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
current->cpuset_mem_spread_rotor =
node_random(¤t->mems_allowed);
return cpuset_spread_node(¤t->cpuset_mem_spread_rotor);
}
int cpuset_slab_spread_node(void)
{
if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
current->cpuset_slab_spread_rotor =
node_random(¤t->mems_allowed);
return cpuset_spread_node(¤t->cpuset_slab_spread_rotor);
}
EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
/**
* cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
* @tsk1: pointer to task_struct of some task.
* @tsk2: pointer to task_struct of some other task.
*
* Description: Return true if @tsk1's mems_allowed intersects the
* mems_allowed of @tsk2. Used by the OOM killer to determine if
* one of the task's memory usage might impact the memory available
* to the other.
**/
int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
const struct task_struct *tsk2)
{
return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
}
#define CPUSET_NODELIST_LEN (256)
/**
* cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
* @task: pointer to task_struct of some task.
*
* Description: Prints @task's name, cpuset name, and cached copy of its
* mems_allowed to the kernel log. Must hold task_lock(task) to allow
* dereferencing task_cs(task).
*/
void cpuset_print_task_mems_allowed(struct task_struct *tsk)
{
/* Statically allocated to prevent using excess stack. */
static char cpuset_nodelist[CPUSET_NODELIST_LEN];
static DEFINE_SPINLOCK(cpuset_buffer_lock);
struct cgroup *cgrp = task_cs(tsk)->css.cgroup;
rcu_read_lock();
spin_lock(&cpuset_buffer_lock);
nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
tsk->mems_allowed);
printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
tsk->comm, cgroup_name(cgrp), cpuset_nodelist);
spin_unlock(&cpuset_buffer_lock);
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)
{
task_lock(current);
fmeter_markevent(&task_cs(current)->fmeter);
task_unlock(current);
}
#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, void *unused_v)
{
struct pid *pid;
struct task_struct *tsk;
char *buf;
struct cgroup_subsys_state *css;
int retval;
retval = -ENOMEM;
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!buf)
goto out;
retval = -ESRCH;
pid = m->private;
tsk = get_pid_task(pid, PIDTYPE_PID);
if (!tsk)
goto out_free;
rcu_read_lock();
css = task_subsys_state(tsk, cpuset_subsys_id);
retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
rcu_read_unlock();
if (retval < 0)
goto out_put_task;
seq_puts(m, buf);
seq_putc(m, '\n');
out_put_task:
put_task_struct(tsk);
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");
seq_nodemask(m, &task->mems_allowed);
seq_printf(m, "\n");
seq_printf(m, "Mems_allowed_list:\t");
seq_nodemask_list(m, &task->mems_allowed);
seq_printf(m, "\n");
}