oom: invoke oom killer for __GFP_NOFAIL

The oom killer must be invoked regardless of the order if the allocation
is __GFP_NOFAIL, otherwise it will loop forever when reclaim fails to free
some memory.

Cc: Nick Piggin <npiggin@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: David Rientjes <rientjes@google.com>
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 c95a77c..c5fb017 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1561,7 +1561,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
                goto out;
 
        /* The OOM killer will not help higher order allocs */
-       if (order > PAGE_ALLOC_COSTLY_ORDER)
+       if (order > PAGE_ALLOC_COSTLY_ORDER && !(gfp_mask & __GFP_NOFAIL))
                goto out;
 
        /* Exhausted what can be done so it's blamo time */
@@ -1781,11 +1781,13 @@ rebalance:
                                goto got_pg;
 
                        /*
-                        * The OOM killer does not trigger for high-order allocations
-                        * but if no progress is being made, there are no other
-                        * options and retrying is unlikely to help
+                        * The OOM killer does not trigger for high-order
+                        * ~__GFP_NOFAIL allocations so if no progress is being
+                        * made, there are no other options and retrying is
+                        * unlikely to help.
                         */
-                       if (order > PAGE_ALLOC_COSTLY_ORDER)
+                       if (order > PAGE_ALLOC_COSTLY_ORDER &&
+                                               !(gfp_mask & __GFP_NOFAIL))
                                goto nopage;
 
                        goto restart;