memcg: fix oops in mem_cgroup_shrink_usage
Hugh Dickins [Tue, 12 Aug 2008 22:08:41 +0000 (15:08 -0700)]
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>

mm/memcontrol.c

index 7056c3b..0f1f7a7 100644 (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));