Re: 2.6.33-rc1: kernel BUG at fs/ext4/inode.c:1063 (sparc)

From: tytso
Date: Sun Dec 27 2009 - 22:52:19 EST

kernel BUG at fs/ext4/inode.c:1063!

> >> Here is output of 2.6.33-rc2 plus Ted's patch
> >>
> >> EXT4-fs (sda1): inode #1387643: mdb_free (1) < mdb_claim (2) BUG
> >

OK, i've been able to reproduce the problem using xfsqa test #74
(fstest) when an ext3 file system is mounted the ext4 file system
driver. I was then able to bisect it down to commit d21cd8f6, which
was introduced between 2.6.33-rc1 and 2.6.33-rc2, as part of
quota/ext4 patch series pushed by Jan.

I then tested v2.6.33-rc2 with commit d21cd8 reverted, and I was not
able to replicate the BUG. More investigation is needed, but if we
compare the potential quota deadlock with the apparently
fairly-easy-to-replicate BUG, if we can't find a better fix fairly
quickly we should probably just revert this commit for now.

- Ted

commit d21cd8f163ac44b15c465aab7306db931c606908
Author: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
AuthorDate: Thu Dec 10 03:31:45 2009 +0000
Commit: Jan Kara <jack@xxxxxxx>
CommitDate: Wed Dec 23 13:44:12 2009 +0100

ext4: Fix potential quota deadlock

We have to delay vfs_dq_claim_space() until allocation context destruction.
Currently we have following call-trace:
ext4_mb_new_blocks()
/* task is already holding ac->alloc_semp */
->ext4_mb_mark_diskspace_used
->vfs_dq_claim_space() /* acquire dqptr_sem here. Possible deadlock */
->ext4_mb_release_context() /* drop ac->alloc_semp here */

Let's move quota claiming to ext4_da_update_reserve_space()

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.32-rc7 #18
-------------------------------------------------------
write-truncate-/3465 is trying to acquire lock:
(&s->s_dquot.dqptr_sem){++++..}, at: [<c025e73b>] dquot_claim_space+0x3b/0x1b0

but task is already holding lock:
(&meta_group_info[i]->alloc_sem){++++..}, at: [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (&meta_group_info[i]->alloc_sem){++++..}:
[<c017d04b>] __lock_acquire+0xd7b/0x1260
[<c017d5ea>] lock_acquire+0xba/0xd0
[<c0527191>] down_read+0x51/0x90
[<c02ce962>] ext4_mb_load_buddy+0xb2/0x370
[<c02d0c1c>] ext4_mb_free_blocks+0x46c/0x870
[<c029c9d3>] ext4_free_blocks+0x73/0x130
[<c02c8cfc>] ext4_ext_truncate+0x76c/0x8d0
[<c02a8087>] ext4_truncate+0x187/0x5e0
[<c01e0f7b>] vmtruncate+0x6b/0x70
[<c022ec02>] inode_setattr+0x62/0x190
[<c02a2d7a>] ext4_setattr+0x25a/0x370
[<c022ee81>] notify_change+0x151/0x340
[<c021349d>] do_truncate+0x6d/0xa0
[<c0221034>] may_open+0x1d4/0x200
[<c022412b>] do_filp_open+0x1eb/0x910
[<c021244d>] do_sys_open+0x6d/0x140
[<c021258e>] sys_open+0x2e/0x40
[<c0103100>] sysenter_do_call+0x12/0x32

-> #2 (&ei->i_data_sem){++++..}:
[<c017d04b>] __lock_acquire+0xd7b/0x1260
[<c017d5ea>] lock_acquire+0xba/0xd0
[<c0527191>] down_read+0x51/0x90
[<c02a5787>] ext4_get_blocks+0x47/0x450
[<c02a74c1>] ext4_getblk+0x61/0x1d0
[<c02a7a7f>] ext4_bread+0x1f/0xa0
[<c02bcddc>] ext4_quota_write+0x12c/0x310
[<c0262d23>] qtree_write_dquot+0x93/0x120
[<c0261708>] v2_write_dquot+0x28/0x30
[<c025d3fb>] dquot_commit+0xab/0xf0
[<c02be977>] ext4_write_dquot+0x77/0x90
[<c02be9bf>] ext4_mark_dquot_dirty+0x2f/0x50
[<c025e321>] dquot_alloc_inode+0x101/0x180
[<c029fec2>] ext4_new_inode+0x602/0xf00
[<c02ad789>] ext4_create+0x89/0x150
[<c0221ff2>] vfs_create+0xa2/0xc0
[<c02246e7>] do_filp_open+0x7a7/0x910
[<c021244d>] do_sys_open+0x6d/0x140
[<c021258e>] sys_open+0x2e/0x40
[<c0103100>] sysenter_do_call+0x12/0x32

-> #1 (&sb->s_type->i_mutex_key#7/4){+.+...}:
[<c017d04b>] __lock_acquire+0xd7b/0x1260
[<c017d5ea>] lock_acquire+0xba/0xd0
[<c0526505>] mutex_lock_nested+0x65/0x2d0
[<c0260c9d>] vfs_load_quota_inode+0x4bd/0x5a0
[<c02610af>] vfs_quota_on_path+0x5f/0x70
[<c02bc812>] ext4_quota_on+0x112/0x190
[<c026345a>] sys_quotactl+0x44a/0x8a0
[<c0103100>] sysenter_do_call+0x12/0x32

-> #0 (&s->s_dquot.dqptr_sem){++++..}:
[<c017d361>] __lock_acquire+0x1091/0x1260
[<c017d5ea>] lock_acquire+0xba/0xd0
[<c0527191>] down_read+0x51/0x90
[<c025e73b>] dquot_claim_space+0x3b/0x1b0
[<c02cb95f>] ext4_mb_mark_diskspace_used+0x36f/0x380
[<c02d210a>] ext4_mb_new_blocks+0x34a/0x530
[<c02c83fb>] ext4_ext_get_blocks+0x122b/0x13c0
[<c02a5966>] ext4_get_blocks+0x226/0x450
[<c02a5ff3>] mpage_da_map_blocks+0xc3/0xaa0
[<c02a6ed6>] ext4_da_writepages+0x506/0x790
[<c01de272>] do_writepages+0x22/0x50
[<c01d766d>] __filemap_fdatawrite_range+0x6d/0x80
[<c01d7b9b>] filemap_flush+0x2b/0x30
[<c02a40ac>] ext4_alloc_da_blocks+0x5c/0x60
[<c029e595>] ext4_release_file+0x75/0xb0
[<c0216b59>] __fput+0xf9/0x210
[<c0216c97>] fput+0x27/0x30
[<c02122dc>] filp_close+0x4c/0x80
[<c014510e>] put_files_struct+0x6e/0xd0
[<c01451b7>] exit_files+0x47/0x60
[<c0146a24>] do_exit+0x144/0x710
[<c0147028>] do_group_exit+0x38/0xa0
[<c0159abc>] get_signal_to_deliver+0x2ac/0x410
[<c0102849>] do_notify_resume+0xb9/0x890
[<c01032d2>] work_notifysig+0x13/0x21

other info that might help us debug this:

3 locks held by write-truncate-/3465:
#0: (jbd2_handle){+.+...}, at: [<c02e1f8f>] start_this_handle+0x38f/0x5c0
#1: (&ei->i_data_sem){++++..}, at: [<c02a57f6>] ext4_get_blocks+0xb6/0x450
#2: (&meta_group_info[i]->alloc_sem){++++..}, at: [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370

stack backtrace:
Pid: 3465, comm: write-truncate- Not tainted 2.6.32-rc7 #18
Call Trace:
[<c0524cb3>] ? printk+0x1d/0x22
[<c017ac9a>] print_circular_bug+0xca/0xd0
[<c017d361>] __lock_acquire+0x1091/0x1260
[<c016bca2>] ? sched_clock_local+0xd2/0x170
[<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
[<c017d5ea>] lock_acquire+0xba/0xd0
[<c025e73b>] ? dquot_claim_space+0x3b/0x1b0
[<c0527191>] down_read+0x51/0x90
[<c025e73b>] ? dquot_claim_space+0x3b/0x1b0
[<c025e73b>] dquot_claim_space+0x3b/0x1b0
[<c02cb95f>] ext4_mb_mark_diskspace_used+0x36f/0x380
[<c02d210a>] ext4_mb_new_blocks+0x34a/0x530
[<c02c601d>] ? ext4_ext_find_extent+0x25d/0x280
[<c02c83fb>] ext4_ext_get_blocks+0x122b/0x13c0
[<c016bca2>] ? sched_clock_local+0xd2/0x170
[<c016be60>] ? sched_clock_cpu+0x120/0x160
[<c016beef>] ? cpu_clock+0x4f/0x60
[<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
[<c052712c>] ? down_write+0x8c/0xa0
[<c02a5966>] ext4_get_blocks+0x226/0x450
[<c016be60>] ? sched_clock_cpu+0x120/0x160
[<c016beef>] ? cpu_clock+0x4f/0x60
[<c017908b>] ? trace_hardirqs_off+0xb/0x10
[<c02a5ff3>] mpage_da_map_blocks+0xc3/0xaa0
[<c01d69cc>] ? find_get_pages_tag+0x16c/0x180
[<c01d6860>] ? find_get_pages_tag+0x0/0x180
[<c02a73bd>] ? __mpage_da_writepage+0x16d/0x1a0
[<c01dfc4e>] ? pagevec_lookup_tag+0x2e/0x40
[<c01ddf1b>] ? write_cache_pages+0xdb/0x3d0
[<c02a7250>] ? __mpage_da_writepage+0x0/0x1a0
[<c02a6ed6>] ext4_da_writepages+0x506/0x790
[<c016beef>] ? cpu_clock+0x4f/0x60
[<c016bca2>] ? sched_clock_local+0xd2/0x170
[<c016be60>] ? sched_clock_cpu+0x120/0x160
[<c016be60>] ? sched_clock_cpu+0x120/0x160
[<c02a69d0>] ? ext4_da_writepages+0x0/0x790
[<c01de272>] do_writepages+0x22/0x50
[<c01d766d>] __filemap_fdatawrite_range+0x6d/0x80
[<c01d7b9b>] filemap_flush+0x2b/0x30
[<c02a40ac>] ext4_alloc_da_blocks+0x5c/0x60
[<c029e595>] ext4_release_file+0x75/0xb0
[<c0216b59>] __fput+0xf9/0x210
[<c0216c97>] fput+0x27/0x30
[<c02122dc>] filp_close+0x4c/0x80
[<c014510e>] put_files_struct+0x6e/0xd0
[<c01451b7>] exit_files+0x47/0x60
[<c0146a24>] do_exit+0x144/0x710
[<c017b163>] ? lock_release_holdtime+0x33/0x210
[<c0528137>] ? _spin_unlock_irq+0x27/0x30
[<c0147028>] do_group_exit+0x38/0xa0
[<c017babb>] ? trace_hardirqs_on+0xb/0x10
[<c0159abc>] get_signal_to_deliver+0x2ac/0x410
[<c0102849>] do_notify_resume+0xb9/0x890
[<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
[<c017b163>] ? lock_release_holdtime+0x33/0x210
[<c0165b50>] ? autoremove_wake_function+0x0/0x50
[<c017ba54>] ? trace_hardirqs_on_caller+0x134/0x190
[<c017babb>] ? trace_hardirqs_on+0xb/0x10
[<c0300ba4>] ? security_file_permission+0x14/0x20
[<c0215761>] ? vfs_write+0x131/0x190
[<c0214f50>] ? do_sync_write+0x0/0x120
[<c0103115>] ? sysenter_do_call+0x27/0x32
[<c01032d2>] work_notifysig+0x13/0x21

CC: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>

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