From c54839a722a02818677bcabe57e957f0ce4f841d Mon Sep 17 00:00:00 2001
From: Jaewon Kim <jaewon31.kim@samsung.com>
Date: Tue, 8 Sep 2015 15:02:21 -0700
Subject: [PATCH] vmscan: fix increasing nr_isolated incurred by putback
 unevictable pages

reclaim_clean_pages_from_list() assumes that shrink_page_list() returns
number of pages removed from the candidate list.  But shrink_page_list()
puts back mlocked pages without passing it to caller and without
counting as nr_reclaimed.  This increases nr_isolated.

To fix this, this patch changes shrink_page_list() to pass unevictable
pages back to caller.  Caller will take care those pages.

Minchan said:

It fixes two issues.

1. With unevictable page, cma_alloc will be successful.

Exactly speaking, cma_alloc of current kernel will fail due to
unevictable pages.

2. fix leaking of NR_ISOLATED counter of vmstat

With it, too_many_isolated works.  Otherwise, it could make hang until
the process get SIGKILL.

Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0b1aab411cb0..8276a3a615ca 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1196,7 +1196,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		if (PageSwapCache(page))
 			try_to_free_swap(page);
 		unlock_page(page);
-		putback_lru_page(page);
+		list_add(&page->lru, &ret_pages);
 		continue;
 
 activate_locked:
-- 
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