From ac44d354d5c9ced49b1165d6496f134501134219 Mon Sep 17 00:00:00 2001 From: Balbir Singh Date: Thu, 7 Feb 2008 00:14:18 -0800 Subject: [PATCH] Memory controller use rcu_read_lock() in mem_cgroup_cache_charge() 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 Acked-by: KAMEZAWA Hiroyuki Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 975e89935d52..160101a05b4d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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; } /* -- 2.39.5