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Memory controller use rcu_read_lock() in mem_cgroup_cache_charge()

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Hugh Dickins noticed that we were using rcu_dereference() without
rcu_read_lock() in the cache charging routine. The patch below fixes
this problem

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Balbir Singh 2008-02-07 00:14:18 -08:00 committed by Linus Torvalds
parent 217bc3194d
commit ac44d354d5
1 changed files with 7 additions and 3 deletions
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10
mm/memcontrol.c
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@ -456,16 +456,20 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask)
{
int ret = 0;
struct mem_cgroup *mem;
if (!mm)
mm = &init_mm;
rcu_read_lock();
mem = rcu_dereference(mm->mem_cgroup);
css_get(&mem->css);
rcu_read_unlock();
if (mem->control_type == MEM_CGROUP_TYPE_ALL)
return mem_cgroup_charge_common(page, mm, gfp_mask,
ret = mem_cgroup_charge_common(page, mm, gfp_mask,
MEM_CGROUP_CHARGE_TYPE_CACHE);
else
return 0;
css_put(&mem->css);
return ret;
}
/*