memcg: make oom killer a no-op when no killable task can be found

It's pointless to try to kill current if select_bad_process() did not find
an eligible task to kill in mem_cgroup_out_of_memory() since it's
guaranteed that current is a member of the memcg that is oom and it is, by
definition, unkillable.

Signed-off-by: David Rientjes <[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Daisuke Nishimura <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index b68e802a7a7d6961a0c1f7709a9cc606d022371c..709aedfaa014946664f2b83857b749d92f79752f 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -479,12 +479,9 @@ void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
        read_lock(&tasklist_lock);
 retry:
        p = select_bad_process(&points, mem);
-       if (PTR_ERR(p) == -1UL)
+       if (!p || PTR_ERR(p) == -1UL)
                goto out;
 
-       if (!p)
-               p = current;
-
        if (oom_kill_process(p, gfp_mask, 0, points, mem,
                                "Memory cgroup out of memory"))
                goto retry;