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Merge branch 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Browse source 
Pull cgroup update from Tejun Heo:
 "cpuset got simplified a bit.  cgroup core got a fix on unified
  hierarchy and grew some effective css related interfaces which will be
  used for blkio support for writeback IO traffic which is currently
  being worked on"

* 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: implement cgroup_get_e_css()
  cgroup: add cgroup_subsys->css_e_css_changed()
  cgroup: add cgroup_subsys->css_released()
  cgroup: fix the async css offline wait logic in cgroup_subtree_control_write()
  cgroup: restructure child_subsys_mask handling in cgroup_subtree_control_write()
  cgroup: separate out cgroup_calc_child_subsys_mask() from cgroup_refresh_child_subsys_mask()
  cpuset: lock vs unlock typo
  cpuset: simplify cpuset_node_allowed API
  cpuset: convert callback_mutex to a spinlock
This commit is contained in:
Linus Torvalds 2014-12-11 18:57:19 -08:00
commit 2756d373a3
10 changed files with 200 additions and 198 deletions
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162
kernel/cpuset.c
View file

@ -248,34 +248,34 @@ static struct cpuset top_cpuset = {
if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
/*
* 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.
* There are two global locks guarding cpuset structures - cpuset_mutex and
* callback_lock. We also require taking task_lock() when dereferencing a
* task's cpuset pointer. See "The task_lock() exception", at the end of this
* comment.
*
* A task must hold both mutexes to modify cpusets. If a task holds
* A task must hold both locks to modify cpusets. If a task holds
* cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
* is the only task able to also acquire callback_mutex and be able to
* is the only task able to also acquire callback_lock and be able to
* modify cpusets. It can perform various checks on the cpuset structure
* first, knowing nothing will change. It can also allocate memory while
* just holding cpuset_mutex. While it is performing these checks, various
* callback routines can briefly acquire callback_mutex to query cpusets.
* Once it is ready to make the changes, it takes callback_mutex, blocking
* callback routines can briefly acquire callback_lock to query cpusets.
* Once it is ready to make the changes, it takes callback_lock, blocking
* everyone else.
*
* Calls to the kernel memory allocator can not be made while holding
* callback_mutex, as that would risk double tripping on callback_mutex
* callback_lock, as that would risk double tripping on callback_lock
* from one of the callbacks into the cpuset code from within
* __alloc_pages().
*
* If a task is only holding callback_mutex, then it has read-only
* If a task is only holding callback_lock, then it has read-only
* access to cpusets.
*
* Now, the task_struct fields mems_allowed and mempolicy may be changed
* by other task, we use alloc_lock in the task_struct fields to protect
* them.
*
* The cpuset_common_file_read() handlers only hold callback_mutex across
* The cpuset_common_file_read() handlers only hold callback_lock across
* small pieces of code, such as when reading out possibly multi-word
* cpumasks and nodemasks.
*
@ -284,7 +284,7 @@ static struct cpuset top_cpuset = {
*/
static DEFINE_MUTEX(cpuset_mutex);
static DEFINE_MUTEX(callback_mutex);
static DEFINE_SPINLOCK(callback_lock);
/*
* CPU / memory hotplug is handled asynchronously.
@ -329,7 +329,7 @@ static struct file_system_type cpuset_fs_type = {
* One way or another, we guarantee to return some non-empty subset
* of cpu_online_mask.
*
* Call with callback_mutex held.
* Call with callback_lock or cpuset_mutex held.
*/
static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
{
@ -347,7 +347,7 @@ static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
* One way or another, we guarantee to return some non-empty subset
* of node_states[N_MEMORY].
*
* Call with callback_mutex held.
* Call with callback_lock or cpuset_mutex held.
*/
static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
{
@ -359,7 +359,7 @@ static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
/*
* update task's spread flag if cpuset's page/slab spread flag is set
*
* Called with callback_mutex/cpuset_mutex held
* Call with callback_lock or cpuset_mutex held.
*/
static void cpuset_update_task_spread_flag(struct cpuset *cs,
struct task_struct *tsk)
@ -886,9 +886,9 @@ static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
continue;
rcu_read_unlock();
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
cpumask_copy(cp->effective_cpus, new_cpus);
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
!cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
@ -953,9 +953,9 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
if (retval < 0)
return retval;
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
/* use trialcs->cpus_allowed as a temp variable */
update_cpumasks_hier(cs, trialcs->cpus_allowed);
@ -1142,9 +1142,9 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
continue;
rcu_read_unlock();
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
cp->effective_mems = *new_mems;
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
!nodes_equal(cp->mems_allowed, cp->effective_mems));
@ -1165,7 +1165,7 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
* 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.
* Call with cpuset_mutex held. May take callback_lock during call.
* Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
* lock each such tasks mm->mmap_sem, scan its vma's and rebind
* their mempolicies to the cpusets new mems_allowed.
@ -1212,9 +1212,9 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
if (retval < 0)
goto done;
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
cs->mems_allowed = trialcs->mems_allowed;
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
/* use trialcs->mems_allowed as a temp variable */
update_nodemasks_hier(cs, &cs->mems_allowed);
@ -1305,9 +1305,9 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
|| (is_spread_page(cs) != is_spread_page(trialcs)));
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
cs->flags = trialcs->flags;
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
rebuild_sched_domains_locked();
@ -1714,7 +1714,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
count = seq_get_buf(sf, &buf);
s = buf;
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
switch (type) {
case FILE_CPULIST:
@ -1741,7 +1741,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
seq_commit(sf, -1);
}
out_unlock:
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
return ret;
}
@ -1958,12 +1958,12 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
cpuset_inc();
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
if (cgroup_on_dfl(cs->css.cgroup)) {
cpumask_copy(cs->effective_cpus, parent->effective_cpus);
cs->effective_mems = parent->effective_mems;
}
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
goto out_unlock;
@ -1990,10 +1990,10 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
}
rcu_read_unlock();
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
cs->mems_allowed = parent->mems_allowed;
cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
out_unlock:
mutex_unlock(&cpuset_mutex);
return 0;
@ -2032,7 +2032,7 @@ static void cpuset_css_free(struct cgroup_subsys_state *css)
static void cpuset_bind(struct cgroup_subsys_state *root_css)
{
mutex_lock(&cpuset_mutex);
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
if (cgroup_on_dfl(root_css->cgroup)) {
cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
@ -2043,7 +2043,7 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css)
top_cpuset.mems_allowed = top_cpuset.effective_mems;
}
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
mutex_unlock(&cpuset_mutex);
}
@ -2128,12 +2128,12 @@ hotplug_update_tasks_legacy(struct cpuset *cs,
{
bool is_empty;
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
cpumask_copy(cs->cpus_allowed, new_cpus);
cpumask_copy(cs->effective_cpus, new_cpus);
cs->mems_allowed = *new_mems;
cs->effective_mems = *new_mems;
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
/*
* Don't call update_tasks_cpumask() if the cpuset becomes empty,
@ -2170,10 +2170,10 @@ hotplug_update_tasks(struct cpuset *cs,
if (nodes_empty(*new_mems))
*new_mems = parent_cs(cs)->effective_mems;
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
cpumask_copy(cs->effective_cpus, new_cpus);
cs->effective_mems = *new_mems;
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
if (cpus_updated)
update_tasks_cpumask(cs);
@ -2259,21 +2259,21 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
/* synchronize cpus_allowed to cpu_active_mask */
if (cpus_updated) {
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
if (!on_dfl)
cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
/* we don't mess with cpumasks of tasks in top_cpuset */
}
/* synchronize mems_allowed to N_MEMORY */
if (mems_updated) {
mutex_lock(&callback_mutex);
spin_lock_irq(&callback_lock);
if (!on_dfl)
top_cpuset.mems_allowed = new_mems;
top_cpuset.effective_mems = new_mems;
mutex_unlock(&callback_mutex);
spin_unlock_irq(&callback_lock);
update_tasks_nodemask(&top_cpuset);
}
@ -2366,11 +2366,13 @@ void __init cpuset_init_smp(void)
void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
{
mutex_lock(&callback_mutex);
unsigned long flags;
spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
guarantee_online_cpus(task_cs(tsk), pmask);
rcu_read_unlock();
mutex_unlock(&callback_mutex);
spin_unlock_irqrestore(&callback_lock, flags);
}
void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
@ -2416,12 +2418,13 @@ void cpuset_init_current_mems_allowed(void)
nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
{
nodemask_t mask;
unsigned long flags;
mutex_lock(&callback_mutex);
spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
guarantee_online_mems(task_cs(tsk), &mask);
rcu_read_unlock();
mutex_unlock(&callback_mutex);
spin_unlock_irqrestore(&callback_lock, flags);
return mask;
}
@ -2440,7 +2443,7 @@ int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
/*
* 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
* callback_lock. If no ancestor is mem_exclusive or mem_hardwall
* (an unusual configuration), then returns the root cpuset.
*/
static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
@ -2451,7 +2454,7 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
}
/**
* cpuset_node_allowed_softwall - Can we allocate on a memory node?
* cpuset_node_allowed - Can we allocate on a memory node?
* @node: is this an allowed node?
* @gfp_mask: memory allocation flags
*
@ -2463,13 +2466,6 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
* 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
@ -2482,13 +2478,12 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
* 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
* Scanning up parent cpusets requires callback_lock. The
* __alloc_pages() routine only calls here with __GFP_HARDWALL bit
* _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
* current tasks mems_allowed came up empty on the first pass over
* the zonelist. So only GFP_KERNEL allocations, if all nodes in the
* cpuset are short of memory, might require taking the callback_mutex
* mutex.
* cpuset are short of memory, might require taking the callback_lock.
*
* The first call here from mm/page_alloc:get_page_from_freelist()
* has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
@ -2505,20 +2500,15 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
* 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)
int __cpuset_node_allowed(int node, gfp_t gfp_mask)
{
struct cpuset *cs; /* current cpuset ancestors */
int allowed; /* is allocation in zone z allowed? */
unsigned long flags;
if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
return 1;
might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
if (node_isset(node, current->mems_allowed))
return 1;
/*
@ -2534,55 +2524,17 @@ int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
return 1;
/* Not hardwall and node outside mems_allowed: scan up cpusets */
mutex_lock(&callback_mutex);
spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
cs = nearest_hardwall_ancestor(task_cs(current));
allowed = node_isset(node, cs->mems_allowed);
rcu_read_unlock();
mutex_unlock(&callback_mutex);
spin_unlock_irqrestore(&callback_lock, flags);
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