linux-kernel - Re: [PATCH] Check PageActive when evictable page and unevicetable page race happen

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Date:	Sun, 24 Apr 2011 11:01:22 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-mm <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Lee Schermerhorn <lee.schermerhorn@...com>
Subject: Re: [PATCH] Check PageActive when evictable page and unevicetable
 page race happen

On Sun, Apr 24, 2011 at 09:25:51AM +0900, Minchan Kim wrote:
> In putback_lru_page, unevictable page can be changed into evictable
> 's one while we move it among lru. So we have checked it again and
> rescued it. But we don't check PageActive, again. It could add
> active page into inactive list so we can see the BUG in isolate_lru_pages.
> (But I didn't see any report because I think it's very subtle)

As I look the code further, that's because lru_cache_add_lru always 
cleans up PageActive regardless of LRU list. 
If active page goes to inactive list, we shouldn't meet the BUG 
but it's apparently wrong. 

-- 
Kind regards,
Minchan Kim
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