From: Matthew Wilcox <matthew@wil.cx>
To: ?????? shin hong <hongshin@gmail.com>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: BUG? deadlock bug at generic_shutdown_
Date: Wed, 29 Jul 2009 21:41:24 -0600 [thread overview]
Message-ID: <20090730034124.GO3711@parisc-linux.org> (raw)
In-Reply-To: <2014bcab0907292029o6617b6a7n944cbd28edd39c10@mail.gmail.com>
On Thu, Jul 30, 2009 at 12:29:57PM +0900, ?????? shin hong wrote:
> Hi. I am reporting a suspected deadlock bug.
>
> generic_shutdown_super() acquires lock_super(sb)
> and then acquires lock_kernel().
It hasn't since commit a9e220f8322e2b0e0b8903fe00265461cffad3f0.
Please work against a current kernel.
> However, do_remount() acquires lock_super() while
> it holds lock_kernel().
>
> Therefore, concurrent execution of generic_shutdown_super()
> and do_remount() may result deadlock.
The reason this wasn't a problem before the commit above is that
generic_shutdown_super() can never execute concurrently with do_remount.
For generic_shutdown_super() to be called, there must be no remaining
references to the super_block. do_remount() must hold a reference to
the super_block.
CONFIG_LOCKDEP finds lock inversion problems; I suspect you're wasting
your time looking for them by hand.
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
prev parent reply other threads:[~2009-07-30 3:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-30 3:29 BUG? deadlock bug at generic_shutdown_ 홍신 shin hong
2009-07-30 3:41 ` Matthew Wilcox [this message]
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