linux-kernel - Re: [Bug 3.4.5] reiserfs: mutex_destroy called with locked mutex

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Message-ID: <CA+55aFyHpgbJ9Pn5xn_ALkvzjQBOWog2qLbwwtrKbPHSGpa6pA@mail.gmail.com>
Date:	Wed, 18 Jul 2012 14:25:02 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	Knut Petersen <Knut_Petersen@...nline.de>,
	linux-kernel@...r.kernel.org, reiserfs-devel@...r.kernel.org
Subject: Re: [Bug 3.4.5] reiserfs: mutex_destroy called with locked mutex

On Wed, Jul 18, 2012 at 2:20 PM, Al Viro <viro@...iv.linux.org.uk> wrote:
> On Wed, Jul 18, 2012 at 09:26:57AM -0700, Linus Torvalds wrote:
>>
>> So I don't think the freeing code could trigger, but a concurrent
>> lookup then trying to look up the new directory (and taking the new
>> directory i_semaphore lock) could happen, afaik.
>
> Umm...  The thing is, we'd get WARN_ON() in iput_final() triggering in
> that scenario before lockdep could complain.

Not for the "look up directory in the dcache, and then lock that
inode" case, afaik. You'd get the lock before iput_final(), no?

So then "unlock_new_inode()" would run with the inode mutex held,
which could explain the lockdep warning, no?

             Linus
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