[patch] mm, migrate: increment fail count on ENOMEM

[David Rientjes]

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.

Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
 mm/migrate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/migrate.c b/mm/migrate.c
--- 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++;