Revert "mm, oom: prevent premature OOM killer invocation for high order request"

Patch series "reintroduce compaction feedback for OOM decisions".

After several people reported OOM's for order-2 allocations in 4.7 due
to Michal Hocko's OOM rework, he reverted the part that considered
compaction feedback [1] in the decisions to retry reclaim/compaction.
This was to provide a fix quickly for 4.8 rc and 4.7 stable series,
while mmotm had an almost complete solution that instead improved
compaction reliability.

This series completes the mmotm solution and reintroduces the compaction
feedback into OOM decisions.  The first two patches restore the state of
mmotm before the temporary solution was merged, the last patch should be
the missing piece for reliability.  The third patch restricts the
hardened compaction to non-costly orders, since costly orders don't
result in OOMs in the first place.

[1] http://marc.info/?i=20160822093249.GA14916%40dhcp22.suse.cz%3E

This patch (of 4):

Commit 6b4e3181d7bd ("mm, oom: prevent premature OOM killer invocation
for high order request") was intended as a quick fix of OOM regressions
for 4.8 and stable 4.7.x kernels.  For a better long-term solution, we
still want to consider compaction feedback, which should be possible
after some more improvements in the following patches.

This reverts commit 6b4e3181d7bd5ca5ab6f45929e4a5ffa7ab4ab7f.

Link: http://lkml.kernel.org/r/20160906135258.18335-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 49 insertions, 2 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e00f545c2398..634806f55120 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3156,6 +3156,54 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
         return NULL;
 }
 
+static inline bool
+should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
+                     enum compact_result compact_result,
+                     enum compact_priority *compact_priority,
+                     int compaction_retries)
+{
+        int max_retries = MAX_COMPACT_RETRIES;
+
+        if (!order)
+                return false;
+
+        /*
+         * compaction considers all the zone as desperately out of memory
+         * so it doesn't really make much sense to retry except when the
+         * failure could be caused by insufficient priority
+         */
+        if (compaction_failed(compact_result)) {
+                if (*compact_priority > MIN_COMPACT_PRIORITY) {
+                        (*compact_priority)--;
+                        return true;
+                }
+                return false;
+        }
+
+        /*
+         * make sure the compaction wasn't deferred or didn't bail out early
+         * due to locks contention before we declare that we should give up.
+         * But do not retry if the given zonelist is not suitable for
+         * compaction.
+         */
+        if (compaction_withdrawn(compact_result))
+                return compaction_zonelist_suitable(ac, order, alloc_flags);
+
+        /*
+         * !costly requests are much more important than __GFP_REPEAT
+         * costly ones because they are de facto nofail and invoke OOM
+         * killer to move on while costly can fail and users are ready
+         * to cope with that. 1/4 retries is rather arbitrary but we
+         * would need much more detailed feedback from compaction to
+         * make a better decision.
+         */
+        if (order > PAGE_ALLOC_COSTLY_ORDER)
+                max_retries /= 4;
+        if (compaction_retries <= max_retries)
+                return true;
+
+        return false;
+}
 #else
 static inline struct page *
 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
@@ -3166,8 +3214,6 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
         return NULL;
 }
 
-#endif /* CONFIG_COMPACTION */
-
 static inline bool
 should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
                      enum compact_result compact_result,
@@ -3194,6 +3240,7 @@ should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_fla
         }
         return false;
 }
+#endif /* CONFIG_COMPACTION */
 
 /* Perform direct synchronous page reclaim */
 static int