oom: skip zombies when iterating tasklist

We shouldn't defer oom killing if a thread has already detached its ->mm
and still has TIF_MEMDIE set.  Memory needs to be freed, so find kill
other threads that pin the same ->mm or find another task to kill.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: <stable@kernel.org>		[2.6.38.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index b5a7b5f46e7a..d7f345e47e73 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -299,6 +299,8 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
         do_each_thread(g, p) {
                 unsigned int points;
 
+                if (!p->mm)
+                        continue;
                 if (oom_unkillable_task(p, mem, nodemask))
                         continue;
 
@@ -324,7 +326,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
                  * the process of exiting and releasing its resources.
                  * Otherwise we could get an easy OOM deadlock.
                  */
-                if ((p->flags & PF_EXITING) && p->mm) {
+                if (p->flags & PF_EXITING) {
                         if (p != current)
                                 return ERR_PTR(-1UL);