Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754050AbZCaKHu (ORCPT ); Tue, 31 Mar 2009 06:07:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752674AbZCaKHf (ORCPT ); Tue, 31 Mar 2009 06:07:35 -0400 Received: from ey-out-2122.google.com ([74.125.78.25]:17047 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752186AbZCaKHe convert rfc822-to-8bit (ORCPT ); Tue, 31 Mar 2009 06:07:34 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=QUCUE3kwwY0VEYKiIKDc3MYkDZ3Onnh56NCryQLGk12sg445UWeZ4VgRrl21iQr2Jg 9qgYZtgXw7VDhMED7ohXy7IL+fgsEnO2vqVV3GIOMmAydjzwjPjJ6Q3HEVwjEHBT8n9C eqNFD5jGZnOllr3pyYIhEu/P7TIIOEW4iuUM0= MIME-Version: 1.0 In-Reply-To: <20090331100150.GF11808@duck.suse.cz> References: <20090325151516.GB14881@atrey.karlin.mff.cuni.cz> <20090325152234.GN23439@duck.suse.cz> <20090325161556.GP23439@duck.suse.cz> <20090325194316.GQ23439@duck.suse.cz> <20090331100150.GF11808@duck.suse.cz> Date: Tue, 31 Mar 2009 14:07:30 +0400 Message-ID: Subject: Re: next-20090310: ext4 hangs From: Alexander Beregalov To: Jan Kara Cc: Theodore Tso , "linux-next@vger.kernel.org" , linux-ext4@vger.kernel.org, LKML , sparclinux@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2912 Lines: 57 2009/3/31 Jan Kara : > On Thu 26-03-09 01:38:32, Alexander Beregalov wrote: >> 2009/3/25 Jan Kara : >> > On Wed 25-03-09 20:07:46, Alexander Beregalov wrote: >> >> 2009/3/25 Jan Kara : >> >> > 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 for the disassembly... >> > >> >> By default gcc inlines journal_submit_data_buffers() >> >> Here is -fno-inline version. Default version is in attach. >   > >  I'm helpless here. I don't see how we can miss a wakeup (plus you seem to > be the only one reporting the bug). Could you please compile and test the kernel > with the attached patch? It will print to kernel log when we go to sleep > waiting for inode commit and when we send wakeups etc. When you hit the > deadlock, please send me your kernel log. It should help with debugging why do > we miss the wakeup. Thanks. Which patch? -- 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/