memcg: fix oops in mem_cgroup_shrink_usage

Got an oops in mem_cgroup_shrink_usage() when testing loop over tmpfs:
yes, of course, loop0 has no mm: other entry points check but this didn't.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2008-08-12 15:08:41 -07:00 committed by Linus Torvalds
parent 3ee1062b4e
commit 9623e078c1

View File

@ -796,6 +796,8 @@ int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
if (mem_cgroup_subsys.disabled)
return 0;
if (!mm)
return 0;
rcu_read_lock();
mem = mem_cgroup_from_task(rcu_dereference(mm->owner));