From: Andrew Morton <akpm@linux-foundation.org>
To: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: kamezawa.hiroyu@jp.fujitsu.com, balbir@in.ibm.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [BUGFIX][PATCH] memcg: fix deadlock between lock_page_cgroup and mapping tree_lock
Date: Wed, 13 May 2009 11:56:26 -0700 [thread overview]
Message-ID: <20090513115626.57844f28.akpm@linux-foundation.org> (raw)
In-Reply-To: <20090513133031.f4be15a8.nishimura@mxp.nes.nec.co.jp>
On Wed, 13 May 2009 13:30:31 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> mapping->tree_lock can be aquired from interrupt context.
> Then, following dead lock can occur.
>
> Assume "A" as a page.
>
> CPU0:
> lock_page_cgroup(A)
> interrupted
> -> take mapping->tree_lock.
> CPU1:
> take mapping->tree_lock
> -> lock_page_cgroup(A)
And we didn't find out about this because lock_page_cgroup() uses
bit_spin_lock(), and lockdep doesn't handle bit_spin_lock().
It would perhaps be useful if one of you guys were to add a spinlock to
struct page, convert lock_page_cgroup() to use that spinlock then run a
full set of tests under lockdep, see if it can shake out any other bugs.
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next prev parent reply other threads:[~2009-05-13 19:00 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-13 4:30 [BUGFIX][PATCH] memcg: fix deadlock between lock_page_cgroup and mapping tree_lock Daisuke Nishimura
2009-05-13 18:56 ` Andrew Morton [this message]
2009-05-13 23:44 ` KAMEZAWA Hiroyuki
2009-05-14 1:48 ` [BUGFIX][PATCH] memcg: fix deadlock between lock_page_cgroupand " Balbir Singh
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