Re: next-20090310: ext4 hangs

[Jan Kara]

> > 2009/3/10 Theodore Tso <tytso@xxxxxxx>:
> > > 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.
  BTW: Is the system SMP?

								Honza
-- 
Jan Kara <jack@xxxxxxx>
SuSE CR Labs
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