mm: avoid endless looping for oom killed tasks

If a task is oom killed and still cannot find memory when trying with
no watermarks, it's better to fail the allocation attempt than to loop
endlessly.  Direct reclaim has already failed and the oom killer will
be a no-op since current has yet to die, so there is no other
alternative for allocations that are not __GFP_NOFAIL.

Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ae28c22a7fdb66ec85539a9693c72cda8ade221d..2dbb2fc68837e5fa0cf5db4d497370cd37a8d5e9 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1794,6 +1794,10 @@ rebalance:
        if (p->flags & PF_MEMALLOC)
                goto nopage;
 
+       /* Avoid allocations with no watermarks from looping endlessly */
+       if (test_thread_flag(TIF_MEMDIE) && !(gfp_mask & __GFP_NOFAIL))
+               goto nopage;
+
        /* Try direct reclaim and then allocating */
        page = __alloc_pages_direct_reclaim(gfp_mask, order,
                                        zonelist, high_zoneidx,