mm,page_alloc: don't call __node_reclaim() with oom_lock held.

We are doing a last second memory allocation attempt before calling
out_of_memory().  But since slab shrinker functions might indirectly
wait for other thread's __GFP_DIRECT_RECLAIM && !__GFP_NORETRY memory
allocations via sleeping locks, calling slab shrinker functions from
node_reclaim() from get_page_from_freelist() with oom_lock held has
possibility of deadlock.  Therefore, make sure that last second memory
allocation attempt does not call slab shrinker functions.

Link: http://lkml.kernel.org/r/1503577106-9196-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
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 7a58eb5757e3bd61d9dadfd8d851b9641454552d..1423da8dd16f5bdc83e20ddf6665b2022a9a6492 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3291,10 +3291,13 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
        /*
         * Go through the zonelist yet one more time, keep very high watermark
         * here, this is only to catch a parallel oom killing, we must fail if
-        * we're still under heavy pressure.
+        * we're still under heavy pressure. But make sure that this reclaim
+        * attempt shall not depend on __GFP_DIRECT_RECLAIM && !__GFP_NORETRY
+        * allocation which will never fail due to oom_lock already held.
         */
-       page = get_page_from_freelist(gfp_mask | __GFP_HARDWALL, order,
-                                       ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
+       page = get_page_from_freelist((gfp_mask | __GFP_HARDWALL) &
+                                     ~__GFP_DIRECT_RECLAIM, order,
+                                     ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
        if (page)
                goto out;