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mm: memcontrol: take a css reference for each charged page

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Charges currently pin the css indirectly by playing tricks during
css_offline(): user pages stall the offlining process until all of them
have been reparented, whereas kmemcg acquires a keep-alive reference if
outstanding kernel pages are detected at that point.

In preparation for removing all this complexity, make the pinning explicit
and acquire a css references for every charged page.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2014-12-10 15:42:42 -08:00 • committed by Linus Torvalds
commit e8ea14cc6e
3 changed files with 92 additions and 24 deletions
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69
include/linux/percpu-refcount.h
View file

@ -146,6 +146,29 @@ static inline bool __ref_is_percpu(struct percpu_ref *ref,
return true;
}
/**
* percpu_ref_get_many - increment a percpu refcount
* @ref: percpu_ref to get
* @nr: number of references to get
*
* Analogous to atomic_long_add().
*
* This function is safe to call as long as @ref is between init and exit.
*/
static inline void percpu_ref_get_many(struct percpu_ref *ref, unsigned long nr)
{
unsigned long __percpu *percpu_count;
rcu_read_lock_sched();
if (__ref_is_percpu(ref, &percpu_count))
this_cpu_add(*percpu_count, nr);
else
atomic_long_add(nr, &ref->count);
rcu_read_unlock_sched();
}
/**
* percpu_ref_get - increment a percpu refcount
* @ref: percpu_ref to get
@ -156,16 +179,7 @@ static inline bool __ref_is_percpu(struct percpu_ref *ref,
*/
static inline void percpu_ref_get(struct percpu_ref *ref)
{
unsigned long __percpu *percpu_count;
rcu_read_lock_sched();
if (__ref_is_percpu(ref, &percpu_count))
this_cpu_inc(*percpu_count);
else
atomic_long_inc(&ref->count);
rcu_read_unlock_sched();
percpu_ref_get_many(ref, 1);
}
/**
@ -230,6 +244,30 @@ static inline bool percpu_ref_tryget_live(struct percpu_ref *ref)
return ret;
}
/**
* percpu_ref_put_many - decrement a percpu refcount
* @ref: percpu_ref to put
* @nr: number of references to put
*
* Decrement the refcount, and if 0, call the release function (which was passed
* to percpu_ref_init())
*
* This function is safe to call as long as @ref is between init and exit.
*/
static inline void percpu_ref_put_many(struct percpu_ref *ref, unsigned long nr)
{
unsigned long __percpu *percpu_count;
rcu_read_lock_sched();
if (__ref_is_percpu(ref, &percpu_count))
this_cpu_sub(*percpu_count, nr);
else if (unlikely(atomic_long_sub_and_test(nr, &ref->count)))
ref->release(ref);
rcu_read_unlock_sched();
}
/**
* percpu_ref_put - decrement a percpu refcount
* @ref: percpu_ref to put
@ -241,16 +279,7 @@ static inline bool percpu_ref_tryget_live(struct percpu_ref *ref)
*/
static inline void percpu_ref_put(struct percpu_ref *ref)
{
unsigned long __percpu *percpu_count;
rcu_read_lock_sched();
if (__ref_is_percpu(ref, &percpu_count))
this_cpu_dec(*percpu_count);
else if (unlikely(atomic_long_dec_and_test(&ref->count)))
ref->release(ref);
rcu_read_unlock_sched();
percpu_ref_put_many(ref, 1);
}
/**