From: Jan Kara Subject: Re: Re: Re: EXT4 regression caused 4eec7 Date: Mon, 13 May 2013 17:17:27 +0200 Message-ID: <20130513151727.GI400@quack.suse.cz> References: <31302271.2821368363898561.JavaMail.weblogic@epml17> <20130513131809.GG400@quack.suse.cz> <20130513135643.GB12883@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , EUNBONG SONG , Theodore Ts'o , Dmitry Monakhov , "linux-ext4@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-xfs@vger.kernel.org" , Dave Chinner To: Zheng Liu Return-path: Content-Disposition: inline In-Reply-To: <20130513135643.GB12883@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon 13-05-13 21:56:43, Zheng Liu wrote: > On Mon, May 13, 2013 at 03:18:09PM +0200, Jan Kara wrote: > > On Sun 12-05-13 13:04:59, EUNBONG SONG wrote: > > > > > > > > > >> Since at this point it's safer to rollback the change and we can > > > >> investigate more deeply how to fix it correctly for the next > > > >> development cycle, this is the patch which I'm testing. > > > > > > >> - Ted > > > > > > > Hello, I've tested with your patch. But the same problem was reproduced. > > > > Currently, I'm trying to git bisect. If i done git bisect, i will let you know. > > > > > > Hi, I've done git bisect. and panic at jbd2_journal_put_journal_head() is caused by > > > ae4647fb7654676fc44a97e86eb35f9f06b99f66: "jbd2: reduce journal_head size." > > > I write just code patch which revert ae4647fb7654676fc44a97e86eb35f9f06b99f66 because > > > I don't know the root cause. > > This is really strange. I've verified the code and all the places > > modifying b_jlist or b_modified are holding bh_state lock so we should be > > safe... > > Hi Jan, > > Could you please take a look at this mail [1]. I don't think we hold > bh_state lock there. > > 1. http://www.spinics.net/lists/linux-ext4/msg38205.html I'll also reply to that thread but: Yes, we don't hold bh_state lock when reading b_jlist in that one case (that's why I wrote 'modify' and not just 'access' in my previous email). But that's really harmless since we don't do any complex operations with b_jlist (only get & set) so we either see an old value or a new one. And that particular use is going away anyway later in my series. Honza -- Jan Kara SUSE Labs, CR