From dfef2ef4027b1304149a65dc33794eab65e8a3bf Mon Sep 17 00:00:00 2001
From: David Rientjes <rientjes@google.com>
Date: Fri, 20 May 2016 16:59:05 -0700
Subject: [PATCH] mm, migrate: increment fail count on ENOMEM

If page migration fails due to -ENOMEM, nr_failed should still be
incremented for proper statistics.

This was encountered recently when all page migration vmstats showed 0,
and inferred that migrate_pages() was never called, although in reality
the first page migration failed because compaction_alloc() failed to
find a migration target.

This patch increments nr_failed so the vmstat is properly accounted on
ENOMEM.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1605191510230.32658@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/migrate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/migrate.c b/mm/migrate.c
index 53ab6398e7a2..9baf41c877ff 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1171,6 +1171,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 
 			switch(rc) {
 			case -ENOMEM:
+				nr_failed++;
 				goto out;
 			case -EAGAIN:
 				retry++;
-- 
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