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From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
        Rafael Aquini <aquini@redhat.com>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
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        Vlastimil Babka <vbabka@suse.cz>,
        Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: [PATCH v2 1/7] mm/migrate: add comment about permanent failure path
Date: Mon,  9 Dec 2013 18:10:42 +0900
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From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Let's add a comment about where the failed page goes to, which makes
code more readable.

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

diff --git a/mm/migrate.c b/mm/migrate.c
index 3747fcd..c6ac87a 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1123,7 +1123,12 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 				nr_succeeded++;
 				break;
 			default:
-				/* Permanent failure */
+				/*
+				 * Permanent failure (-EBUSY, -ENOSYS, etc.):
+				 * unlike -EAGAIN case, the failed page is
+				 * removed from migration page list and not
+				 * retried in the next outer loop.
+				 */
 				nr_failed++;
 				break;
 			}
-- 
1.7.9.5