Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763409AbZCYQQT (ORCPT ); Wed, 25 Mar 2009 12:16:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753446AbZCYQQB (ORCPT ); Wed, 25 Mar 2009 12:16:01 -0400 Received: from cantor.suse.de ([195.135.220.2]:48624 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752947AbZCYQP7 (ORCPT ); Wed, 25 Mar 2009 12:15:59 -0400 Date: Wed, 25 Mar 2009 17:15:56 +0100 From: Jan Kara To: Alexander Beregalov Cc: Theodore Tso , "linux-next@vger.kernel.org" , linux-ext4@vger.kernel.org, LKML Subject: Re: next-20090310: ext4 hangs Message-ID: <20090325161556.GP23439@duck.suse.cz> References: <20090310124658.GE8840@mit.edu> <20090310154745.GF23075@mit.edu> <20090325151122.GA14881@atrey.karlin.mff.cuni.cz> <20090325151516.GB14881@atrey.karlin.mff.cuni.cz> <20090325152234.GN23439@duck.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1896 Lines: 44 On Wed 25-03-09 18:29:10, Alexander Beregalov wrote: > 2009/3/25 Jan Kara : > > On Wed 25-03-09 18:18:43, Alexander Beregalov wrote: > >> 2009/3/25 Jan Kara : > >> >> > So, I think I need to try it on 2.6.29-rc7 again. > >> >> ? I've looked into this. Obviously, what's happenning is that we delete > >> >> an inode and jbd2_journal_release_jbd_inode() finds inode is just under > >> >> writeout in transaction commit and thus it waits. But it gets never woken > >> >> up and because it has a handle from the transaction, every one eventually > >> >> blocks on waiting for a transaction to finish. > >> >> ? But I don't really see how that can happen. The code is really > >> >> straightforward and everything happens under j_list_lock... Strange. > >> > ?BTW: Is the system SMP? > >> No, it is UP system. > > ?Even stranger. And do you have CONFIG_PREEMPT set? > > > >> The bug exists even in 2.6.29, I posted it with a new topic. > > ?OK, I've sort-of expected this. > > CONFIG_PREEMPT_RCU=y > CONFIG_PREEMPT_RCU_TRACE=y > # CONFIG_PREEMPT_NONE is not set > # CONFIG_PREEMPT_VOLUNTARY is not set > CONFIG_PREEMPT=y > CONFIG_DEBUG_PREEMPT=y > # CONFIG_PREEMPT_TRACER is not set > > config is attached. Thanks for the data. I still don't see how the wakeup can get lost. The process even cannot be preempted when we are in the section protected by j_list_lock... Can you send me a disassembly of functions jbd2_journal_release_jbd_inode() and journal_submit_data_buffers() so that I can see whether the compiler has not reordered something unexpectedly? Thanks. Honza -- Jan Kara SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/