oom: skip zombies when iterating tasklist

commit 30e2b41f20b6238f51e7cffb879c7a0f0073f5fe upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index b5a7b5f46e7ac0429e80d0c5f9535f1c7b48e5cd..d7f345e47e73a80dccfe1c6fb820ef3b2a7f1213 100644 (file)
--- 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);