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memcg: fold mem_cgroup_stolen

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It is only used in __mem_cgroup_begin_update_page_stat(), the name is
confusing and 2 routines for one thing also confuse people, so fold this
function seems more clear.

[akpm@linux-foundation.org: fix typo, per Michal]
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Qiang Huang 2014-06-04 16:08:21 -07:00 committed by Linus Torvalds
parent 3fb1c8dcfc
commit bdcbb659fe
1 changed files with 7 additions and 18 deletions
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25
mm/memcontrol.c
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@ -1594,23 +1594,12 @@ static void mem_cgroup_end_move(struct mem_cgroup *memcg)
}
/*
* 2 routines for checking "mem" is under move_account() or not.
* A routine for checking "mem" is under move_account() or not.
*
* mem_cgroup_stolen() - checking whether a cgroup is mc.from or not. This
* is used for avoiding races in accounting. If true,
* pc->mem_cgroup may be overwritten.
*
* mem_cgroup_under_move() - checking a cgroup is mc.from or mc.to or
* under hierarchy of moving cgroups. This is for
* waiting at hith-memory prressure caused by "move".
* Checking a cgroup is mc.from or mc.to or under hierarchy of
* moving cgroups. This is for waiting at high-memory pressure
* caused by "move".
*/
static bool mem_cgroup_stolen(struct mem_cgroup *memcg)
{
VM_BUG_ON(!rcu_read_lock_held());
return atomic_read(&memcg->moving_account) > 0;
}
static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
{
struct mem_cgroup *from;
@ -1653,7 +1642,6 @@ static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
* Take this lock when
* - a code tries to modify page's memcg while it's USED.
* - a code tries to modify page state accounting in a memcg.
* see mem_cgroup_stolen(), too.
*/
static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
unsigned long *flags)
@ -2326,9 +2314,10 @@ again:
* If this memory cgroup is not under account moving, we don't
* need to take move_lock_mem_cgroup(). Because we already hold
* rcu_read_lock(), any calls to move_account will be delayed until
* rcu_read_unlock() if mem_cgroup_stolen() == true.
* rcu_read_unlock().
*/
if (!mem_cgroup_stolen(memcg))
VM_BUG_ON(!rcu_read_lock_held());
if (atomic_read(&memcg->moving_account) <= 0)
return;
move_lock_mem_cgroup(memcg, flags);