kernel-ark/kernel/cpuset.c
David Rientjes b246272ecc cpusets: stall when updating mems_allowed for mempolicy or disjoint nodemask
Kernels where MAX_NUMNODES > BITS_PER_LONG may temporarily see an empty
nodemask in a tsk's mempolicy if its previous nodemask is remapped onto a
new set of allowed cpuset nodes where the two nodemasks, as a result of
the remap, are now disjoint.

c0ff7453bb ("cpuset,mm: fix no node to alloc memory when changing
cpuset's mems") adds get_mems_allowed() to prevent the set of allowed
nodes from changing for a thread.  This causes any update to a set of
allowed nodes to stall until put_mems_allowed() is called.

This stall is unncessary, however, if at least one node remains unchanged
in the update to the set of allowed nodes.  This was addressed by
89e8a244b9 ("cpusets: avoid looping when storing to mems_allowed if one
node remains set"), but it's still possible that an empty nodemask may be
read from a mempolicy because the old nodemask may be remapped to the new
nodemask during rebind.  To prevent this, only avoid the stall if there is
no mempolicy for the thread being changed.

This is a temporary solution until all reads from mempolicy nodemasks can
be guaranteed to not be empty without the get_mems_allowed()
synchronization.

Also moves the check for nodemask intersection inside task_lock() so that
tsk->mems_allowed cannot change.  This ensures that nothing can set this
tsk's mems_allowed out from under us and also protects tsk->mempolicy.

Reported-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-12-20 10:25:04 -08:00

2646 lines
75 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/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>
/*
* Workqueue for cpuset related tasks.
*
* Using kevent workqueue may cause deadlock when memory_migrate
* is set. So we create a separate workqueue thread for cpuset.
*/
static struct workqueue_struct *cpuset_wq;
/*
* 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 cpuset *parent; /* my parent */
struct fmeter fmeter; /* memory_pressure filter */
/* partition number for rebuild_sched_domains() */
int pn;
/* for custom sched domain */
int relax_domain_level;
/* used for walking a cpuset hierarchy */
struct list_head stack_list;
};
/* 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);
}
#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_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 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_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
};
/*
* There are two global mutexes guarding cpuset structures. The first
* is the main control groups cgroup_mutex, accessed via
* cgroup_lock()/cgroup_unlock(). The second is the cpuset-specific
* callback_mutex, below. They can nest. It is ok to first take
* cgroup_mutex, then nest callback_mutex. 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 cgroup_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 cgroup_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(callback_mutex);
/*
* cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist
* buffers. They are statically allocated to prevent using excess stack
* when calling cpuset_print_task_mems_allowed().
*/
#define CPUSET_NAME_LEN (128)
#define CPUSET_NODELIST_LEN (256)
static char cpuset_name[CPUSET_NAME_LEN];
static char cpuset_nodelist[CPUSET_NODELIST_LEN];
static DEFINE_SPINLOCK(cpuset_buffer_lock);
/*
* 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_map. Or if passed a NULL cs from an exit'ing
* task, return cpu_online_map.
*
* One way or another, we guarantee to return some non-empty subset
* of cpu_online_map.
*
* 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 = cs->parent;
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_HIGH_MEMORY].
*
* One way or another, we guarantee to return some non-empty subset
* of node_states[N_HIGH_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_HIGH_MEMORY]))
cs = cs->parent;
if (cs)
nodes_and(*pmask, cs->mems_allowed,
node_states[N_HIGH_MEMORY]);
else
*pmask = node_states[N_HIGH_MEMORY];
BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY]));
}
/*
* update task's spread flag if cpuset's page/slab spread flag is set
*
* Called with callback_mutex/cgroup_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 cgroup_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
* cgroup_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;
/* Each of our child cpusets must be a subset of us */
list_for_each_entry(cont, &cur->css.cgroup->children, sibling) {
if (!is_cpuset_subset(cgroup_cs(cont), trial))
return -EBUSY;
}
/* Remaining checks don't apply to root cpuset */
if (cur == &top_cpuset)
return 0;
par = cur->parent;
/* We must be a subset of our parent cpuset */
if (!is_cpuset_subset(trial, par))
return -EACCES;
/*
* If either I or some sibling (!= me) is exclusive, we can't
* overlap
*/
list_for_each_entry(cont, &par->css.cgroup->children, sibling) {
c = cgroup_cs(cont);
if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
c != cur &&
cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
return -EINVAL;
if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
c != cur &&
nodes_intersects(trial->mems_allowed, c->mems_allowed))
return -EINVAL;
}
/* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
if (cgroup_task_count(cur->css.cgroup)) {
if (cpumask_empty(trial->cpus_allowed) ||
nodes_empty(trial->mems_allowed)) {
return -ENOSPC;
}
}
return 0;
}
#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 *c)
{
LIST_HEAD(q);
list_add(&c->stack_list, &q);
while (!list_empty(&q)) {
struct cpuset *cp;
struct cgroup *cont;
struct cpuset *child;
cp = list_first_entry(&q, struct cpuset, stack_list);
list_del(q.next);
if (cpumask_empty(cp->cpus_allowed))
continue;
if (is_sched_load_balance(cp))
update_domain_attr(dattr, cp);
list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
child = cgroup_cs(cont);
list_add_tail(&child->stack_list, &q);
}
}
}
/*
* 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 cgroup_lock 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)
{
LIST_HEAD(q); /* queue of cpusets to be scanned */
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 */
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;
list_add(&top_cpuset.stack_list, &q);
while (!list_empty(&q)) {
struct cgroup *cont;
struct cpuset *child; /* scans child cpusets of cp */
cp = list_first_entry(&q, struct cpuset, stack_list);
list_del(q.next);
if (cpumask_empty(cp->cpus_allowed))
continue;
/*
* 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 (is_sched_load_balance(cp)) {
csa[csn++] = cp;
continue;
}
list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
child = cgroup_cs(cont);
list_add_tail(&child->stack_list, &q);
}
}
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.
*
* Call with neither cgroup_mutex held nor within get_online_cpus().
* Takes both cgroup_mutex and get_online_cpus().
*
* Cannot be directly called from cpuset code handling changes
* to the cpuset pseudo-filesystem, because it cannot be called
* from code that already holds cgroup_mutex.
*/
static void do_rebuild_sched_domains(struct work_struct *unused)
{
struct sched_domain_attr *attr;
cpumask_var_t *doms;
int ndoms;
get_online_cpus();
/* Generate domain masks and attrs */
cgroup_lock();
ndoms = generate_sched_domains(&doms, &attr);
cgroup_unlock();
/* Have scheduler rebuild the domains */
partition_sched_domains(ndoms, doms, attr);
put_online_cpus();
}
#else /* !CONFIG_SMP */
static void do_rebuild_sched_domains(struct work_struct *unused)
{
}
static int generate_sched_domains(cpumask_var_t **domains,
struct sched_domain_attr **attributes)
{
*domains = NULL;
return 1;
}
#endif /* CONFIG_SMP */
static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);
/*
* Rebuild scheduler domains, asynchronously via workqueue.
*
* 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.
*
* The rebuild_sched_domains() and partition_sched_domains()
* routines must nest cgroup_lock() inside get_online_cpus(),
* but such cpuset changes as these must nest that locking the
* other way, holding cgroup_lock() for much of the code.
*
* So in order to avoid an ABBA deadlock, the cpuset code handling
* these user changes delegates the actual sched domain rebuilding
* to a separate workqueue thread, which ends up processing the
* above do_rebuild_sched_domains() function.
*/
static void async_rebuild_sched_domains(void)
{
queue_work(cpuset_wq, &rebuild_sched_domains_work);
}
/*
* Accomplishes the same scheduler domain rebuild as the above
* async_rebuild_sched_domains(), however it directly calls the
* rebuild routine synchronously rather than calling it via an
* asynchronous work thread.
*
* This can only be called from code that is not holding
* cgroup_mutex (not nested in a cgroup_lock() call.)
*/
void rebuild_sched_domains(void)
{
do_rebuild_sched_domains(NULL);
}
/**
* 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 cgroup_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 cgroup_lock() 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 cgroup_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_map; 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)
async_rebuild_sched_domains();
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 cgroup_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;
repeat:
/*
* 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);
nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
/*
* ensure checking ->mems_allowed_change_disable after setting all new
* allowed nodes.
*
* the read-side task can see an nodemask with new allowed nodes and
* old allowed nodes. and if it allocates page when cpuset clears newly
* disallowed ones continuous, it can see the new allowed bits.
*
* And if setting all new allowed nodes is after the checking, setting
* all new allowed nodes and clearing newly disallowed ones will be done
* continuous, and the read-side task may find no node to alloc page.
*/
smp_mb();
/*
* Allocation of memory is very fast, we needn't sleep when waiting
* for the read-side.
*/
while (need_loop && ACCESS_ONCE(tsk->mems_allowed_change_disable)) {
task_unlock(tsk);
if (!task_curr(tsk))
yield();
goto repeat;
}
/*
* ensure checking ->mems_allowed_change_disable before clearing all new
* disallowed nodes.
*
* if clearing newly disallowed bits before the checking, the read-side
* task may find no node to alloc page.
*/
smp_mb();
mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
tsk->mems_allowed = *newmems;
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 cgroup_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 cgroup_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 cgroup_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 cgroup_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 cgroup_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_HIGH_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_HIGH_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))
async_rebuild_sched_domains();
}
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 cgroup_lock() 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 cgroup_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 cgroup_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)
async_rebuild_sched_domains();
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; cgroup_mutex held */
static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont,
struct task_struct *tsk)
{
struct cpuset *cs = cgroup_cs(cont);
if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
return -ENOSPC;
/*
* Kthreads bound to specific cpus cannot be moved to a new cpuset; we
* cannot 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.
*/
if (tsk->flags & PF_THREAD_BOUND)
return -EINVAL;
return 0;
}
static int cpuset_can_attach_task(struct cgroup *cgrp, struct task_struct *task)
{
return security_task_setscheduler(task);
}
/*
* Protected by cgroup_lock. The nodemasks must be stored globally because
* dynamically allocating them is not allowed in pre_attach, and they must
* persist among pre_attach, attach_task, and attach.
*/
static cpumask_var_t cpus_attach;
static nodemask_t cpuset_attach_nodemask_from;
static nodemask_t cpuset_attach_nodemask_to;
/* Set-up work for before attaching each task. */
static void cpuset_pre_attach(struct cgroup *cont)
{
struct cpuset *cs = cgroup_cs(cont);
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);
}
/* Per-thread attachment work. */
static void cpuset_attach_task(struct cgroup *cont, struct task_struct *tsk)
{
int err;
struct cpuset *cs = cgroup_cs(cont);
/*
* can_attach beforehand should guarantee that this doesn't fail.
* TODO: have a better way to handle failure here
*/
err = set_cpus_allowed_ptr(tsk, cpus_attach);
WARN_ON_ONCE(err);
cpuset_change_task_nodemask(tsk, &cpuset_attach_nodemask_to);
cpuset_update_task_spread_flag(cs, tsk);
}
static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont,
struct cgroup *oldcont, struct task_struct *tsk)
{
struct mm_struct *mm;
struct cpuset *cs = cgroup_cs(cont);
struct cpuset *oldcs = cgroup_cs(oldcont);
/*
* 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(tsk);
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);
}
}
/* 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)
{
int retval = 0;
struct cpuset *cs = cgroup_cs(cgrp);
cpuset_filetype_t type = cft->private;
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
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;
}
cgroup_unlock();
return retval;
}
static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
{
int retval = 0;
struct cpuset *cs = cgroup_cs(cgrp);
cpuset_filetype_t type = cft->private;
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
switch (type) {
case FILE_SCHED_RELAX_DOMAIN_LEVEL:
retval = update_relax_domain_level(cs, val);
break;
default:
retval = -EINVAL;
break;
}
cgroup_unlock();
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)
{
int retval = 0;
struct cpuset *cs = cgroup_cs(cgrp);
struct cpuset *trialcs;
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
trialcs = alloc_trial_cpuset(cs);
if (!trialcs) {
retval = -ENOMEM;
goto out;
}
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:
cgroup_unlock();
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,
},
};
static struct cftype cft_memory_pressure_enabled = {
.name = "memory_pressure_enabled",
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
.private = FILE_MEMORY_PRESSURE_ENABLED,
};
static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
{
int err;
err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
if (err)
return err;
/* memory_pressure_enabled is in root cpuset only */
if (!cont->parent)
err = cgroup_add_file(cont, ss,
&cft_memory_pressure_enabled);
return err;
}
/*
* post_clone() is called during cgroup_create() when the
* clone_children mount argument was specified. The cgroup
* can not yet have any tasks.
*
* Currently we refuse to set up the cgroup - thereby
* refusing the task to be entered, and as a result refusing
* the sys_unshare() or clone() which initiated it - if any
* sibling cpusets have exclusive cpus or mem.
*
* If this becomes a problem for some users who wish to
* allow that scenario, then cpuset_post_clone() could be
* changed to grant parent->cpus_allowed-sibling_cpus_exclusive
* (and likewise for mems) to the new cgroup. Called with cgroup_mutex
* held.
*/
static void cpuset_post_clone(struct cgroup_subsys *ss,
struct cgroup *cgroup)
{
struct cgroup *parent, *child;
struct cpuset *cs, *parent_cs;
parent = cgroup->parent;
list_for_each_entry(child, &parent->children, sibling) {
cs = cgroup_cs(child);
if (is_mem_exclusive(cs) || is_cpu_exclusive(cs))
return;
}
cs = cgroup_cs(cgroup);
parent_cs = cgroup_cs(parent);
mutex_lock(&callback_mutex);
cs->mems_allowed = parent_cs->mems_allowed;
cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed);
mutex_unlock(&callback_mutex);
return;
}
/*
* cpuset_create - create a cpuset
* ss: cpuset cgroup subsystem
* cont: control group that the new cpuset will be part of
*/
static struct cgroup_subsys_state *cpuset_create(
struct cgroup_subsys *ss,
struct cgroup *cont)
{
struct cpuset *cs;
struct cpuset *parent;
if (!cont->parent) {
return &top_cpuset.css;
}
parent = cgroup_cs(cont->parent);
cs = kmalloc(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);
}
cs->flags = 0;
if (is_spread_page(parent))
set_bit(CS_SPREAD_PAGE, &cs->flags);
if (is_spread_slab(parent))
set_bit(CS_SPREAD_SLAB, &cs->flags);
set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
cpumask_clear(cs->cpus_allowed);
nodes_clear(cs->mems_allowed);
fmeter_init(&cs->fmeter);
cs->relax_domain_level = -1;
cs->parent = parent;
number_of_cpusets++;
return &cs->css ;
}
/*
* If the cpuset being removed has its flag 'sched_load_balance'
* enabled, then simulate turning sched_load_balance off, which
* will call async_rebuild_sched_domains().
*/
static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
{
struct cpuset *cs = cgroup_cs(cont);
if (is_sched_load_balance(cs))
update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
number_of_cpusets--;
free_cpumask_var(cs->cpus_allowed);
kfree(cs);
}
struct cgroup_subsys cpuset_subsys = {
.name = "cpuset",
.create = cpuset_create,
.destroy = cpuset_destroy,
.can_attach = cpuset_can_attach,
.can_attach_task = cpuset_can_attach_task,
.pre_attach = cpuset_pre_attach,
.attach_task = cpuset_attach_task,
.attach = cpuset_attach,
.populate = cpuset_populate,
.post_clone = cpuset_post_clone,
.subsys_id = cpuset_subsys_id,
.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;
}
/**
* cpuset_do_move_task - move a given task to another cpuset
* @tsk: pointer to task_struct the task to move
* @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
*
* Called by cgroup_scan_tasks() for each task in a cgroup.
* Return nonzero to stop the walk through the tasks.
*/
static void cpuset_do_move_task(struct task_struct *tsk,
struct cgroup_scanner *scan)
{
struct cgroup *new_cgroup = scan->data;
cgroup_attach_task(new_cgroup, tsk);
}
/**
* move_member_tasks_to_cpuset - move tasks from one cpuset to another
* @from: cpuset in which the tasks currently reside
* @to: cpuset to which the tasks will be moved
*
* Called with cgroup_mutex held
* callback_mutex must not be held, as cpuset_attach() will take it.
*
* The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
* calling callback functions for each.
*/
static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to)
{
struct cgroup_scanner scan;
scan.cg = from->css.cgroup;
scan.test_task = NULL; /* select all tasks in cgroup */
scan.process_task = cpuset_do_move_task;
scan.heap = NULL;
scan.data = to->css.cgroup;
if (cgroup_scan_tasks(&scan))
printk(KERN_ERR "move_member_tasks_to_cpuset: "
"cgroup_scan_tasks failed\n");
}
/*
* 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.
*
* Called with cgroup_mutex held
* callback_mutex must not be held, as cpuset_attach() will take it.
*/
static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
{
struct cpuset *parent;
/*
* The cgroup's css_sets list is in use if there are tasks
* in the cpuset; the list is empty if there are none;
* the cs->css.refcnt seems always 0.
*/
if (list_empty(&cs->css.cgroup->css_sets))
return;
/*
* Find its next-highest non-empty parent, (top cpuset
* has online cpus, so can't be empty).
*/
parent = cs->parent;
while (cpumask_empty(parent->cpus_allowed) ||
nodes_empty(parent->mems_allowed))
parent = parent->parent;
move_member_tasks_to_cpuset(cs, parent);
}
/*
* Walk the specified cpuset subtree and look for empty cpusets.
* The tasks of such cpuset must be moved to a parent cpuset.
*
* Called with cgroup_mutex held. We take callback_mutex to modify
* cpus_allowed and mems_allowed.
*
* This walk processes the tree from top to bottom, completing one layer
* before dropping down to the next. It always processes a node before
* any of its children.
*
* For now, since we lack memory hot unplug, we'll never see a cpuset
* that has tasks along with an empty 'mems'. But if we did see such
* a cpuset, we'd handle it just like we do if its 'cpus' was empty.
*/
static void scan_for_empty_cpusets(struct cpuset *root)
{
LIST_HEAD(queue);
struct cpuset *cp; /* scans cpusets being updated */
struct cpuset *child; /* scans child cpusets of cp */
struct cgroup *cont;
static nodemask_t oldmems; /* protected by cgroup_mutex */
list_add_tail((struct list_head *)&root->stack_list, &queue);
while (!list_empty(&queue)) {
cp = list_first_entry(&queue, struct cpuset, stack_list);
list_del(queue.next);
list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
child = cgroup_cs(cont);
list_add_tail(&child->stack_list, &queue);
}
/* Continue past cpusets with all cpus, mems online */
if (cpumask_subset(cp->cpus_allowed, cpu_active_mask) &&
nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
continue;
oldmems = cp->mems_allowed;
/* Remove offline cpus and mems from this cpuset. */
mutex_lock(&callback_mutex);
cpumask_and(cp->cpus_allowed, cp->cpus_allowed,
cpu_active_mask);
nodes_and(cp->mems_allowed, cp->mems_allowed,
node_states[N_HIGH_MEMORY]);
mutex_unlock(&callback_mutex);
/* Move tasks from the empty cpuset to a parent */
if (cpumask_empty(cp->cpus_allowed) ||
nodes_empty(cp->mems_allowed))
remove_tasks_in_empty_cpuset(cp);
else {
update_tasks_cpumask(cp, NULL);
update_tasks_nodemask(cp, &oldmems, NULL);
}
}
}
/*
* The top_cpuset tracks what CPUs and Memory Nodes are online,
* period. This 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.
*
* This routine ensures that top_cpuset.cpus_allowed tracks
* cpu_active_mask on each CPU hotplug (cpuhp) event.
*
* Called within get_online_cpus(). Needs to call cgroup_lock()
* before calling generate_sched_domains().
*/
void cpuset_update_active_cpus(void)
{
struct sched_domain_attr *attr;
cpumask_var_t *doms;
int ndoms;
cgroup_lock();
mutex_lock(&callback_mutex);
cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
mutex_unlock(&callback_mutex);
scan_for_empty_cpusets(&top_cpuset);
ndoms = generate_sched_domains(&doms, &attr);
cgroup_unlock();
/* Have scheduler rebuild the domains */
partition_sched_domains(ndoms, doms, attr);
}
#ifdef CONFIG_MEMORY_HOTPLUG
/*
* Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
* Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
* See also the previous routine cpuset_track_online_cpus().
*/
static int cpuset_track_online_nodes(struct notifier_block *self,
unsigned long action, void *arg)
{
static nodemask_t oldmems; /* protected by cgroup_mutex */
cgroup_lock();
switch (action) {
case MEM_ONLINE:
oldmems = top_cpuset.mems_allowed;
mutex_lock(&callback_mutex);
top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
mutex_unlock(&callback_mutex);
update_tasks_nodemask(&top_cpuset, &oldmems, NULL);
break;
case MEM_OFFLINE:
/*
* needn't update top_cpuset.mems_allowed explicitly because
* scan_for_empty_cpusets() will update it.
*/
scan_for_empty_cpusets(&top_cpuset);
break;
default:
break;
}
cgroup_unlock();
return NOTIFY_OK;
}
#endif
/**
* 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_HIGH_MEMORY];
hotplug_memory_notifier(cpuset_track_online_nodes, 10);
cpuset_wq = create_singlethread_workqueue("cpuset");
BUG_ON(!cpuset_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_map, 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);
}
int cpuset_cpus_allowed_fallback(struct task_struct *tsk)
{
const struct cpuset *cs;
int cpu;
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.
*/
cpu = cpumask_any_and(&tsk->cpus_allowed, cpu_active_mask);
if (cpu >= nr_cpu_ids) {
/*
* Either tsk->cpus_allowed is wrong (see above) or it
* is actually empty. The latter case is only possible
* if we are racing with remove_tasks_in_empty_cpuset().
* Like above we can temporary set any mask and rely on
* set_cpus_allowed_ptr() as synchronization point.
*/
do_set_cpus_allowed(tsk, cpu_possible_mask);
cpu = cpumask_any(cpu_active_mask);
}
return cpu;
}
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_HIGH_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)) && cs->parent)
cs = cs->parent;
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_unlock - release lock on cpuset changes
*
* Undo the lock taken in a previous cpuset_lock() call.
*/
void cpuset_unlock(void)
{
mutex_unlock(&callback_mutex);
}
/**
* 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(&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_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)
{
struct dentry *dentry;
dentry = task_cs(tsk)->css.cgroup->dentry;
spin_lock(&cpuset_buffer_lock);
snprintf(cpuset_name, CPUSET_NAME_LEN,
dentry ? (const char *)dentry->d_name.name : "/");
nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
tsk->mems_allowed);
printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
tsk->comm, cpuset_name, cpuset_nodelist);
spin_unlock(&cpuset_buffer_lock);
}
/*
* 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 cgroup_mutex, keeping cpuset_attach() from changing it
* anyway.
*/
static 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;
retval = -EINVAL;
cgroup_lock();
css = task_subsys_state(tsk, cpuset_subsys_id);
retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
if (retval < 0)
goto out_unlock;
seq_puts(m, buf);
seq_putc(m, '\n');
out_unlock:
cgroup_unlock();
put_task_struct(tsk);
out_free:
kfree(buf);
out:
return retval;
}
static int cpuset_open(struct inode *inode, struct file *file)
{
struct pid *pid = PROC_I(inode)->pid;
return single_open(file, proc_cpuset_show, pid);
}
const struct file_operations proc_cpuset_operations = {
.open = cpuset_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
#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");
}