linux-kernel - Re: 2.6.21 reiserfs -- cicular locking?

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Date:	Fri, 27 Apr 2007 14:20:17 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Jeff Mahoney <jeffm@...e.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	David Brownell <david-b@...bell.net>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	reiserfs-dev@...esys.com
Subject: Re: 2.6.21 reiserfs -- cicular locking?

At Fri, 27 Apr 2007 07:09:01 -0400,
Jeff Mahoney wrote:
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Takashi Iwai wrote:
> > At Fri, 27 Apr 2007 12:09:03 +0200,
> > I wrote:
> >> I got a similar bug right now at the fresh boot of 2.6.21.
> >>
> >>
> >> ReiserFS: sda2: found reiserfs format "3.6" with standard journal
> >> ReiserFS: sda2: using ordered data mode
> >> ReiserFS: sda2: journal params: device sda2, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
> >> ReiserFS: sda2: checking transaction log (sda2)
> >> ReiserFS: sda2: Using r5 hash to sort names
> >> ReiserFS: sda2: Removing [3613 1354701 0x0 SD]..done
> >> ReiserFS: sda2: There were 1 uncompleted unlinks/truncates. Completed
> >>
> >> =======================================================
> >> [ INFO: possible circular locking dependency detected ]
> >> 2.6.21-work #1
> >> -------------------------------------------------------
> >> mktemp/1459 is trying to acquire lock:
> >>  (&REISERFS_I(inode)->xattr_sem){..--}, at: [<e08a5236>] reiserfs_cache_default_acl+0x2a/0x9c [reiserfs]
> >>
> >> but task is already holding lock:
> >>  (&inode->i_mutex){--..}, at: [<c016d7dc>] open_namei+0xe2/0x5a2
> >>
> >> which lock already depends on the new lock.
> > The message disappears when I revert the patch:
> > 
> > commit 9b7f375505f5611efb562065b57814b28a81abc3
> > Author: Jeff Mahoney <jeffm@...e.com>
> > Date:   Mon Apr 23 14:41:17 2007 -0700
> > 
> >     reiserfs: fix xattr root locking/refcount bug
> >     
> > 
> > So, likely a newly introduced bug after rc7...
> 
> I got a message with a trace similar to this from Vladimir before I
> submitted that patch. I'm not sure how to annotate this, since the
> xattr_sem can never be taken in the manner described. Internal inodes
> are protected by I_PRIVATE.

Hm, then maybe my case was just a coincidence.

FWIW, I can reproduce the deadlock warning at each time I boot
non-patched 2.6.21, and after reverting the patch, it disappeared.


Takashi
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