linux-kernel - Re: next-20090310: ext4 hangs

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Message-ID: <20090325151122.GA14881@atrey.karlin.mff.cuni.cz>
Date:	Wed, 25 Mar 2009 16:11:22 +0100
From:	Jan Kara <jack@...e.cz>
To:	Alexander Beregalov <a.beregalov@...il.com>
Cc:	Theodore Tso <tytso@....edu>,
	"linux-next@...r.kernel.org" <linux-next@...r.kernel.org>,
	linux-ext4@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: next-20090310: ext4 hangs

> 2009/3/10 Theodore Tso <tytso@....edu>:
> > On Tue, Mar 10, 2009 at 05:18:55PM +0300, Alexander Beregalov wrote:
> >> > Thanks for reporting this; does it show up on stock 2.6.29-rc7?
> >> No, I can not reproduce it.
> >> It is a slow system, I would not like to bisect it, only if it is the
> >> last possibility.
> >
> > Just to be clear; you weren't able to reproduce it on stock 2.6.29-rc7
> > ---- does it reproduce easily on linux-next?
> Right.
> But now I am not sure 2.6.29-rc7 is not affected, I will try to
> reproduce it again.
> 
> >
> > Next question --- does the system hang completely, or just the dbench
> > process (and probably any process that tries touching the filesystem
> System is responsible.
> > that's hung up)?  Do you have a serial console, or someone of
> > recording all of the dumps coming from sysrq-t?  The two stack traces
> I can read dmesg.
> > you gave weren't the ones causing the problem, but rather the ones
> > waiting for the journal lock.
> 
> SysRq : Show State
> 
> <..>
> 
> kjournald2    D 0000000000557a0c     0  1547      2
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [0000000000557a0c] jbd2_journal_commit_transaction+0x208/0x1718
>  [000000000055d758] kjournald2+0x14c/0x318
>  [0000000000465d34] kthread+0x48/0x7c
>  [000000000042b364] kernel_thread+0x3c/0x54
>  [0000000000465c88] kthreadd+0xc8/0x12c
> pdflush       D 000000000055716c     0  2021      2
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055716c] start_this_handle+0x374/0x508
>  [0000000000557500] jbd2_journal_start+0xbc/0x11c
>  [000000000053a438] ext4_journal_start_sb+0x5c/0x84
>  [000000000052dd84] ext4_da_writepages+0x1a8/0x404
>  [0000000000490ec0] do_writepages+0x40/0x78
>  [00000000004d0ff8] __writeback_single_inode+0x198/0x330
>  [00000000004d15d8] generic_sync_sb_inodes+0x238/0x3c4
>  [00000000004d1984] writeback_inodes+0xb0/0x114
>  [00000000004915c0] background_writeout+0xc8/0x114
>  [0000000000492004] pdflush+0x128/0x1e0
>  [0000000000465d34] kthread+0x48/0x7c
>  [000000000042b364] kernel_thread+0x3c/0x54
>  [0000000000465c88] kthreadd+0xc8/0x12c
> dbench        D 000000000055716c     0  2024      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055716c] start_this_handle+0x374/0x508
>  [0000000000557500] jbd2_journal_start+0xbc/0x11c
>  [000000000053a438] ext4_journal_start_sb+0x5c/0x84
>  [000000000052a9b8] ext4_dirty_inode+0xd4/0xf0
>  [00000000004d1a14] __mark_inode_dirty+0x2c/0x188
>  [00000000004c7714] touch_atime+0x160/0x178
>  [00000000004c2a3c] vfs_readdir+0x88/0xb0
>  [00000000004eab90] compat_sys_getdents+0x3c/0x8c
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> dbench        D 000000000055716c     0  2025      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055716c] start_this_handle+0x374/0x508
>  [0000000000557500] jbd2_journal_start+0xbc/0x11c
>  [000000000053a438] ext4_journal_start_sb+0x5c/0x84
>  [000000000052a9b8] ext4_dirty_inode+0xd4/0xf0
>  [00000000004d1a14] __mark_inode_dirty+0x2c/0x188
>  [00000000004c7714] touch_atime+0x160/0x178
>  [00000000004c2a3c] vfs_readdir+0x88/0xb0
>  [00000000004eab90] compat_sys_getdents+0x3c/0x8c
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> dbench        D 000000000055716c     0  2026      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055716c] start_this_handle+0x374/0x508
>  [0000000000557500] jbd2_journal_start+0xbc/0x11c
>  [000000000053a438] ext4_journal_start_sb+0x5c/0x84
>  [000000000052a9b8] ext4_dirty_inode+0xd4/0xf0
>  [00000000004d1a14] __mark_inode_dirty+0x2c/0x188
>  [00000000004c7714] touch_atime+0x160/0x178
>  [000000000048b56c] generic_file_aio_read+0x578/0x620
>  [00000000004b5254] do_sync_read+0x90/0xe0
>  [00000000004b5c40] vfs_read+0x7c/0x11c
>  [00000000004b5d30] SyS_pread64+0x50/0x7c
>  [000000000043f778] sys32_pread64+0x20/0x34
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> dbench        D 000000000055716c     0  2027      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055716c] start_this_handle+0x374/0x508
>  [0000000000557500] jbd2_journal_start+0xbc/0x11c
>  [000000000053a438] ext4_journal_start_sb+0x5c/0x84
>  [000000000052a9b8] ext4_dirty_inode+0xd4/0xf0
>  [00000000004d1a14] __mark_inode_dirty+0x2c/0x188
>  [00000000004c757c] file_update_time+0xe0/0x118
>  [000000000048aef4] __generic_file_aio_write_nolock+0x280/0x380
>  [000000000048b930] generic_file_aio_write+0x58/0xc8
>  [0000000000526274] ext4_file_write+0xa8/0x15c
>  [00000000004b5174] do_sync_write+0x90/0xe0
>  [00000000004b5a40] vfs_write+0x7c/0x11c
>  [00000000004b5b30] SyS_pwrite64+0x50/0x7c
>  [000000000043f744] sys32_pwrite64+0x20/0x34
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> dbench        D 000000000055716c     0  2028      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055716c] start_this_handle+0x374/0x508
>  [0000000000557500] jbd2_journal_start+0xbc/0x11c
>  [000000000053a438] ext4_journal_start_sb+0x5c/0x84
>  [000000000052b958] ext4_da_write_begin+0x98/0x1a0
>  [000000000048a8dc] generic_file_buffered_write+0xe4/0x2b8
>  [000000000048afd0] __generic_file_aio_write_nolock+0x35c/0x380
>  [000000000048b930] generic_file_aio_write+0x58/0xc8
>  [0000000000526274] ext4_file_write+0xa8/0x15c
>  [00000000004b5174] do_sync_write+0x90/0xe0
>  [00000000004b5a40] vfs_write+0x7c/0x11c
>  [00000000004b5b30] SyS_pwrite64+0x50/0x7c
>  [000000000043f744] sys32_pwrite64+0x20/0x34
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> dbench        D 000000000055c010     0  2029      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055c010] jbd2_journal_release_jbd_inode+0x94/0xd8
>  [0000000000535bb4] ext4_clear_inode+0x2c/0x3c
>  [00000000004c7b1c] clear_inode+0xac/0x124
>  [0000000000527e48] ext4_free_inode+0x7c/0x3d4
>  [000000000052f884] ext4_delete_inode+0x218/0x29c
>  [00000000004c86b4] generic_delete_inode+0x8c/0x124
>  [00000000004c876c] generic_drop_inode+0x20/0x19c
>  [00000000004c77a4] iput+0x78/0x88
>  [00000000004c0200] do_unlinkat+0xf8/0x154
>  [00000000004c0270] SyS_unlink+0x14/0x24
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> dbench        D 000000000055cf84     0  2030      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055cf84] jbd2_log_wait_commit+0x144/0x1a8
>  [0000000000555cdc] jbd2_journal_stop+0x32c/0x37c
>  [0000000000557594] jbd2_journal_force_commit+0x34/0x48
>  [0000000000536d14] ext4_force_commit+0x30/0x50
>  [00000000005296b8] ext4_write_inode+0x80/0xa0
>  [00000000004d1044] __writeback_single_inode+0x1e4/0x330
>  [00000000004d11b0] sync_inode+0x20/0x40
>  [00000000005263ec] ext4_sync_file+0xc4/0x118
>  [00000000004d46f0] vfs_fsync+0x6c/0xa0
>  [00000000004d474c] do_fsync+0x28/0x44
>  [00000000004d47a4] SyS_fsync+0x14/0x28
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> dbench        D 000000000055716c     0  2031      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055716c] start_this_handle+0x374/0x508
>  [0000000000557500] jbd2_journal_start+0xbc/0x11c
>  [000000000053a438] ext4_journal_start_sb+0x5c/0x84
>  [000000000052b958] ext4_da_write_begin+0x98/0x1a0
>  [000000000048a8dc] generic_file_buffered_write+0xe4/0x2b8
>  [000000000048afd0] __generic_file_aio_write_nolock+0x35c/0x380
>  [000000000048b930] generic_file_aio_write+0x58/0xc8
>  [0000000000526274] ext4_file_write+0xa8/0x15c
>  [00000000004b5174] do_sync_write+0x90/0xe0
>  [00000000004b5a40] vfs_write+0x7c/0x11c
>  [00000000004b5b30] SyS_pwrite64+0x50/0x7c
>  [000000000043f744] sys32_pwrite64+0x20/0x34
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> dbench        D 000000000055716c     0  2032      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055716c] start_this_handle+0x374/0x508
>  [0000000000557500] jbd2_journal_start+0xbc/0x11c
>  [000000000053a438] ext4_journal_start_sb+0x5c/0x84
>  [000000000052a9b8] ext4_dirty_inode+0xd4/0xf0
>  [00000000004d1a14] __mark_inode_dirty+0x2c/0x188
>  [00000000004c7714] touch_atime+0x160/0x178
>  [00000000004c2a3c] vfs_readdir+0x88/0xb0
>  [00000000004eab90] compat_sys_getdents+0x3c/0x8c
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> dbench        D 000000000055716c     0  2033      1
> Call Trace:
>  [0000000000768bcc] schedule+0x18/0x40
>  [000000000055716c] start_this_handle+0x374/0x508
>  [0000000000557500] jbd2_journal_start+0xbc/0x11c
>  [000000000053a438] ext4_journal_start_sb+0x5c/0x84
>  [000000000052a9b8] ext4_dirty_inode+0xd4/0xf0
>  [00000000004d1a14] __mark_inode_dirty+0x2c/0x188
>  [00000000004c7714] touch_atime+0x160/0x178
>  [000000000048b56c] generic_file_aio_read+0x578/0x620
>  [00000000004b5254] do_sync_read+0x90/0xe0
>  [00000000004b5c40] vfs_read+0x7c/0x11c
>  [00000000004b5d30] SyS_pread64+0x50/0x7c
>  [000000000043f778] sys32_pread64+0x20/0x34
>  [0000000000406154] linux_sparc_syscall32+0x34/0x40
> 
> 
> >
> > I don't think is related to BZ #12579, although some of the symptoms
> > look superficially the same.
> >
> >                                                        - Ted
> >
> > P.S.  What are your dbench parameters, and how big is your filesystem,
> > so I can try to reproduce it on my side?  And how long do you
> > typically need to run before this triggers?  Thanks!
> 
> It is 2G filesystem, I run
> `dbench -c /usr/share/dbench/client.txt 10` or 5 clients.
> 
> Yesterday it happened when I run it for the first time, but today I
> run it 10 times before I got the deadlock.
> 
> 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.

									Honza
-- 
Jan Kara <jack@...e.cz>
SuSE CR Labs
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