linux-kernel - Re: [patch 1/3] mm: fix pageref leak in do_swap

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Message-ID: <20090421031419.GB30001@balbir.in.ibm.com>
Date:	Tue, 21 Apr 2009 08:44:20 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 1/3] mm: fix pageref leak in do_swap_page()

* Johannes Weiner <hannes@...xchg.org> [2009-04-20 22:24:43]:

> By the time the memory cgroup code is notified about a swapin we
> already hold a reference on the fault page.
> 
> If the cgroup callback fails make sure to unlock AND release the page
> or we leak the reference.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> Cc: Balbir Singh <balbir@...ux.vnet.ibm.com>

Seems reasonable to me, could you make the changelog more verbose and
mention that lookup_swap_cache() gets a reference to the page and we
need to release the extra reference.

BTW, have you had any luck reproducing the issue? How did you catch
the problem?

-- 
	Balbir
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