Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758273AbXEORwV (ORCPT ); Tue, 15 May 2007 13:52:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753686AbXEORwJ (ORCPT ); Tue, 15 May 2007 13:52:09 -0400 Received: from keetweej.vanheusden.com ([213.84.46.114]:47795 "EHLO keetweej.vanheusden.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754836AbXEORwG (ORCPT ); Tue, 15 May 2007 13:52:06 -0400 Date: Tue, 15 May 2007 19:52:03 +0200 From: Folkert van Heusden To: Jan Kara Cc: Michal Piotrowski , akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [2.6.21] circular locking dependency found in QUOTA OFF Message-ID: <20070515175203.GE18551@vanheusden.com> References: <4646082D.2080502@shaw.ca> <46479E95.6050507@tmr.com> <20070513235341.GA4270@havoc.gtf.org> <46486DEC.1080506@tmr.com> <3262.62.177.207.163.1179152484.squirrel@klant.bhosted.nl> <6bffcb0e0705141043m6a5b7d22p11ec15723f3f8593@mail.gmail.com> <20070515140939.GB14987@duck.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070515140939.GB14987@duck.suse.cz> Organization: www.unixexpert.nl X-Chameleon-Return-To: folkert@vanheusden.com X-Xfmail-Return-To: folkert@vanheusden.com X-Phonenumber: +31-6-41278122 X-URL: http://www.vanheusden.com/ X-PGP-KeyID: 1F28D8AE X-GPG-fingerprint: AC89 09CE 41F2 00B4 FCF2 B174 3019 0E8C 1F28 D8AE X-Key: http://pgp.surfnet.nl:11371/pks/lookup?op=get&search=0x1F28D8AE Read-Receipt-To: Reply-By: Wed May 16 19:10:49 CEST 2007 X-Message-Flag: MultiTail - tail on steroids User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8986 Lines: 206 I'm afraid it doesn't compile: CHK include/linux/version.h CHK include/linux/utsrelease.h CHK include/linux/compile.h CC fs/dquot.o CC fs/quota.o fs/quota.c: In function `quota_sync_sb': fs/quota.c:180: error: `I_MUTEX_NESTED' undeclared (first use in this function) fs/quota.c:180: error: (Each undeclared identifier is reported only once fs/quota.c:180: error: for each function it appears in.) make[1]: *** [fs/quota.o] Error 1 make: *** [fs] Error 2 On Tue, May 15, 2007 at 04:09:39PM +0200, Jan Kara wrote: > Hi, > > Thanks for report. It seems like a lockdep problem. i_mutex for quota > files is below dqonoff_sem. We were already fixing this for filesystem > specific quota IO functions but obviously we've missed a few cases. I > wonder why it showed up only now... Anyway, attached is a fix. Andrew, > would you add it? Thanks. > > Honza > > On Mon 14-05-07 19:43:18, Michal Piotrowski wrote: > > [adding Jan and fsdevel to CC] > > > > Hi Folkert, > > > > On 14/05/07, Folkert van Heusden wrote: > > >Hi, > > > > > >When I cleanly reboot my pc running 2.6.21 on a P4 with HT and 2GB of ram > > >and system on an 1-filesystem IDE disk, I get the following circular > > >locking dependency error: > > > > > >[330961.226405] ======================================================= > > >[330961.226489] [ INFO: possible circular locking dependency detected ] > > >[330961.226531] 2.6.21 #5 > > >[330961.226569] ------------------------------------------------------- > > >[330961.226611] quotaoff/12249 is trying to acquire lock: > > >[330961.226652] (&sb->s_type->i_mutex_key#4){--..}, at: [] > > >mutex_lock+0x8/0xa > > >[330961.226861] > > >[330961.226862] but task is already holding lock: > > >[330961.226938] (&s->s_dquot.dqonoff_mutex){--..}, at: [] > > >mutex_lock+0x8/0xa > > >[330961.227111] > > >[330961.227111] which lock already depends on the new lock. > > >[330961.227112] > > >[330961.227225] > > >[330961.227225] the existing dependency chain (in reverse order) is: > > >[330961.227303] > > >[330961.227303] -> #1 (&s->s_dquot.dqonoff_mutex){--..}: > > >[330961.227473] [] check_prev_add+0x15b/0x281 > > >[330961.227766] [] check_prevs_add+0x8b/0xe8 > > >[330961.228056] [] __lock_acquire+0x692/0xb81 > > >[330961.228353] [] lock_acquire+0x62/0x81 > > >[330961.228643] [] __mutex_lock_slowpath+0x75/0x28c > > >[330961.228934] [] mutex_lock+0x8/0xa > > >[330961.229221] [] vfs_quota_on_inode+0xc1/0x25f > > >[330961.229513] [] vfs_quota_on+0x75/0x79 > > >[330961.229803] [] ext3_quota_on+0x95/0xb0 > > >[330961.230093] [] do_quotactl+0xc9/0x2dd > > >[330961.230384] [] sys_quotactl+0x84/0xd6 > > >[330961.230673] [] syscall_call+0x7/0xb > > >[330961.230963] [] 0xffffffff > > >[330961.231268] > > >[330961.231268] -> #0 (&sb->s_type->i_mutex_key#4){--..}: > > >[330961.231469] [] check_prev_add+0x34/0x281 > > >[330961.231759] [] check_prevs_add+0x8b/0xe8 > > >[330961.232049] [] __lock_acquire+0x692/0xb81 > > >[330961.232344] [] lock_acquire+0x62/0x81 > > >[330961.232632] [] __mutex_lock_slowpath+0x75/0x28c > > >[330961.232923] [] mutex_lock+0x8/0xa > > >[330961.233211] [] vfs_quota_off+0x1cf/0x260 > > >[330961.233500] [] do_quotactl+0x29f/0x2dd > > >[330961.233792] [] sys_quotactl+0x84/0xd6 > > >[330961.234081] [] syscall_call+0x7/0xb > > >[330961.234503] [] 0xffffffff > > >[330961.234795] > > >[330961.234795] other info that might help us debug this: > > >[330961.234796] > > >[330961.234908] 2 locks held by quotaoff/12249: > > >[330961.234947] #0: (&type->s_umount_key#15){----}, at: [] > > >get_super+0x53/0x94 > > >[330961.235183] #1: (&s->s_dquot.dqonoff_mutex){--..}, at: [] > > >mutex_lock+0x8/0xa > > >[330961.235386] > > >[330961.235387] stack backtrace: > > >[330961.235462] [] show_trace_log_lvl+0x1a/0x30 > > >[330961.235535] [] show_trace+0x12/0x14 > > >[330961.235606] [] dump_stack+0x16/0x18 > > >[330961.235679] [] print_circular_bug_tail+0x6f/0x71 > > >[330961.235753] [] check_prev_add+0x34/0x281 > > >[330961.235825] [] check_prevs_add+0x8b/0xe8 > > >[330961.235897] [] __lock_acquire+0x692/0xb81 > > >[330961.235969] [] lock_acquire+0x62/0x81 > > >[330961.236041] [] __mutex_lock_slowpath+0x75/0x28c > > >[330961.236113] [] mutex_lock+0x8/0xa > > >[330961.236185] [] vfs_quota_off+0x1cf/0x260 > > >[330961.236257] [] do_quotactl+0x29f/0x2dd > > >[330961.236330] [] sys_quotactl+0x84/0xd6 > > >[330961.236402] [] syscall_call+0x7/0xb > > >[330961.236473] ======================= > > > > > > > Is this a 2.6.21 regression? > > > > Regards, > > Michal > > > > -- > > Michal K. K. Piotrowski > > Kernel Monkeys > > (http://kernel.wikidot.com/start) > -- > Jan Kara > SuSE CR Labs > i_mutex on quota files is special. Unlike i_mutexes for other inodes it is > acquired under dqonoff_mutex. Tell lockdep about this lock ranking. Also > comment and code in quota_sync_sb() seem to be bogus (as i_mutex for quota > file can be acquired under dqonoff_mutex). Move truncate_inode_pages() > call under dqonoff_mutex and save some problems with races... > > Signed-off-by: Jan Kara > > diff -rupX /home/jack/.kerndiffexclude linux-2.6.21/fs/dquot.c linux-2.6.21-1-quota_lockdep/fs/dquot.c > --- linux-2.6.21/fs/dquot.c 2007-05-15 14:18:47.000000000 +0200 > +++ linux-2.6.21-1-quota_lockdep/fs/dquot.c 2007-05-15 14:22:47.000000000 +0200 > @@ -1421,7 +1421,7 @@ int vfs_quota_off(struct super_block *sb > /* If quota was reenabled in the meantime, we have > * nothing to do */ > if (!sb_has_quota_enabled(sb, cnt)) { > - mutex_lock(&toputinode[cnt]->i_mutex); > + mutex_lock_nested(&toputinode[cnt]->i_mutex, I_MUTEX_QUOTA); > toputinode[cnt]->i_flags &= ~(S_IMMUTABLE | > S_NOATIME | S_NOQUOTA); > truncate_inode_pages(&toputinode[cnt]->i_data, 0); > diff -rupX /home/jack/.kerndiffexclude linux-2.6.21/fs/quota.c linux-2.6.21-1-quota_lockdep/fs/quota.c > --- linux-2.6.21/fs/quota.c 2006-11-29 22:57:37.000000000 +0100 > +++ linux-2.6.21-1-quota_lockdep/fs/quota.c 2007-05-15 15:15:44.000000000 +0200 > @@ -158,7 +158,6 @@ static int check_quotactl_valid(struct s > static void quota_sync_sb(struct super_block *sb, int type) > { > int cnt; > - struct inode *discard[MAXQUOTAS]; > > sb->s_qcop->quota_sync(sb, type); > /* This is not very clever (and fast) but currently I don't know about > @@ -168,29 +167,21 @@ static void quota_sync_sb(struct super_b > sb->s_op->sync_fs(sb, 1); > sync_blockdev(sb->s_bdev); > > - /* Now when everything is written we can discard the pagecache so > - * that userspace sees the changes. We need i_mutex and so we could > - * not do it inside dqonoff_mutex. Moreover we need to be carefull > - * about races with quotaoff() (that is the reason why we have own > - * reference to inode). */ > + /* > + * Now when everything is written we can discard the pagecache so > + * that userspace sees the changes. > + */ > mutex_lock(&sb_dqopt(sb)->dqonoff_mutex); > for (cnt = 0; cnt < MAXQUOTAS; cnt++) { > - discard[cnt] = NULL; > if (type != -1 && cnt != type) > continue; > if (!sb_has_quota_enabled(sb, cnt)) > continue; > - discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]); > + mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex, I_MUTEX_NESTED); > + truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0); > + mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex); > } > mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); > - for (cnt = 0; cnt < MAXQUOTAS; cnt++) { > - if (discard[cnt]) { > - mutex_lock(&discard[cnt]->i_mutex); > - truncate_inode_pages(&discard[cnt]->i_data, 0); > - mutex_unlock(&discard[cnt]->i_mutex); > - iput(discard[cnt]); > - } > - } > } > > void sync_dquots(struct super_block *sb, int type) Folkert van Heusden -- www.vanheusden.com/multitail - win een vlaai van multivlaai! zorg ervoor dat multitail opgenomen wordt in Fedora Core, AIX, Solaris of HP/UX en win een vlaai naar keuze ---------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com - 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/