From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date: Tue, 21 Jan 2014 23:51:14 +0000 (-0800)
Subject: mm/migrate: add comment about permanent failure path
X-Git-Tag: upstream/snapshot3+hdmi~3612^2~3
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=354a3363363724c21ea2e4b28370e27983c2452e;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

mm/migrate: add comment about permanent failure path

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

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/migrate.c b/mm/migrate.c
index f9e1635..626ca3c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1125,7 +1125,12 @@ 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;
 			}