linux-kernel - Re: [PATCH 1/1] jbd2: fix incorrect unlock on j_list

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Message-ID: <20161013032112.iy4hohrqplsajtye@thunk.org>
Date:   Wed, 12 Oct 2016 23:21:13 -0400
From:   Theodore Ts'o <tytso@....edu>
To:     Andreas Dilger <adilger@...ger.ca>
Cc:     Taesoo Kim <tsgatesv@...il.com>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, taesoo@...ech.edu,
        changwoo@...ech.edu, sanidhya@...ech.edu, blee@...ech.edu,
        csong84@...ech.edu, stable@...r.kernel.org,
        "Faccini, Bruno" <bruno.faccini@...el.com>
Subject: Re: [PATCH 1/1] jbd2: fix incorrect unlock on j_list_lock

On Wed, Oct 12, 2016 at 04:58:35PM -0600, Andreas Dilger wrote:
> On Mar 17, 2015, at 8:08 PM, Taesoo Kim <tsgatesv@...il.com> wrote:
> > 
> > When 'jh->b_transaction == transaction' (asserted by below)
> > 
> >         J_ASSERT_JH(jh, (jh->b_transaction == transaction || ...
> > 
> > 'journal->j_list_lock' will be incorrectly unlocked, since
> > spin_lock() is called only in the 'if' and 'else-if' blocks but
> > not in the missing 'else' case, which results in a hang or an oops....
> > 
> > Signed-off-by: Taesoo Kim <tsgatesv@...il.com>
> 
> We've hit this repeatedly on kernels with commit v3.14-rc2-30-g6e4862a
> "jbd2: minimize region locked by j_list_lock in journal_get_create_access"
> under heavy load and this patch has fixed the problem.
> 
> It should also be considered for stable kernels after 3.14.
> 
> [I've updated the above commit message slightly to give more details.]
> 
> Reviewed-by: Andreas Dilger <adilger@...ger.ca>

Thanks, applied.

Apologies, this got lost which is why I hadn't handled it earlier.

	   	    	       	      - Ted