linux-kernel - Re: INFO: possible circular locking dependency detected 3.1.0-rc2-00190-g3210d19

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Message-ID: <CA+5PVA5GcDMSLxQJb-HhqokA+vZuDvnQN3bsmucmk30mVHN+0A@mail.gmail.com>
Date:	Mon, 22 Aug 2011 09:27:01 -0400
From:	Josh Boyer <jwboyer@...il.com>
To:	Al Viro <viro@...iv.linux.org.uk>, "Theodore Ts'o" <tytso@....edu>
Cc:	"Justin P. Mattock" <justinmattock@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: INFO: possible circular locking dependency detected 3.1.0-rc2-00190-g3210d19

On Mon, Aug 22, 2011 at 9:16 AM, Al Viro <viro@...iv.linux.org.uk> wrote:
> On Mon, Aug 22, 2011 at 09:09:14AM -0400, Josh Boyer wrote:
>
>> We've had a report of this on 3.0.1 as well.  Slightly different
>> scenario and fs, but the locks in question are the same.
>> https://bugzilla.redhat.com/show_bug.cgi?id=730998
>>
>> It seems that with CONFIG_PROVE_LOCKING on, might_fault will always
>> attempt to grab mm->mmap_sem.  The common flow here is that getdents
>> calls filldir, which calls copy_to_user, which is what is calling
>> might_fault.
>>
>> Beyond that, I'm a bit over my head at the moment because I don't know
>> if the VFS is right and we just need some more lockdep annotations or
>> if there really is a problem.
>
> Don't grab ->i_mutex in ->evict_inode().  Why are you doing that, anyway?

I've no idea.  Let's ask Ted!

josh
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