From: Zdenek Kabelac <zkabelac@redhat.com>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: dm-devel@redhat.com, Stephen Boyd <sboyd@codeaurora.org>,
"Alasdair G. Kergon" <agk@redhat.com>
Subject: Re: [PATCH] dm-snapshot: workaround for a lockdep warning
Date: Wed, 18 Sep 2013 08:57:29 +0200 [thread overview]
Message-ID: <52394ED9.5010308@redhat.com> (raw)
In-Reply-To: <alpine.LRH.2.02.1309172006001.24061@file01.intranet.prod.int.rdu2.redhat.com>
Dne 18.9.2013 02:08, Mikulas Patocka napsal(a):
>
>
> On Tue, 17 Sep 2013, Mikulas Patocka wrote:
>
>> BTW. this patch is no longer needed on 3.11 because md->io_lock was
>> removed there, so the false lockdep warning doesn't happen.
>>
>> So we need to get this patch to stable trees 3.5 to 3.10, but not
>> upstream. How to push the patch there without pushing it upstream?
>>
>> Mikulas
>
> It's more complicated than that - the original Zdenek's report shows that
> the false warning happened on kernel "3.11.1-300.fc20.x86_64+debug". But I
> am not able to reproduce the bug on 3.11, I only reproduced it on 3.5-3.10
> kernels.
>
> Zdenek, could you reproduce the bug on kernel 3.11?
>
> Mikulas
>
Since I do not have clean 3.11 at my hands - I've reproduced it with my -rc6
kernel (few patches based on 8495e9c4a9616c9d19f23182d0536485902259db)
With enabled kmemleak=on lockdep.prove_locking=1 lockdep.lock_stat=1.
[ 173.077483] device-mapper: snapshots: Invalidating snapshot: Unable to
allocate exception.
[ 173.077928] ======================================================
[ 173.077930] [ INFO: possible circular locking dependency detected ]
[ 173.077934] 3.11.0-rc6-00153-gf4c4c6a #160 Not tainted
[ 173.077936] -------------------------------------------------------
[ 173.077939] kworker/u4:3/50 is trying to acquire lock:
[ 173.077941] ((&req.work)){+.+...}, at: [<ffffffff81067915>]
flush_work+0x5/0x60
[ 173.077954]
but task is already holding lock:
[ 173.077957] (&s->lock){++++..}, at: [<ffffffffa0a71b3a>]
snapshot_map+0x2aa/0x3a0 [dm_snapshot]
[ 173.077968]
which lock already depends on the new lock.
[ 173.077971]
the existing dependency chain (in reverse order) is:
[ 173.077974]
-> #1 (&s->lock){++++..}:
[ 173.077980] [<ffffffff810bd5e3>] lock_acquire+0x93/0x200
[ 173.077986] [<ffffffff8158df60>] _raw_spin_lock+0x40/0x80
[ 173.077991] [<ffffffff815849b9>] __slab_alloc.constprop.67+0x141/0x50d
[ 173.077996] [<ffffffff8118bd42>] kmem_cache_alloc+0x252/0x290
[ 173.078001] [<ffffffff8119f969>] create_object+0x39/0x310
[ 173.078006] [<ffffffff8157e2ae>] kmemleak_alloc+0x4e/0xb0
[ 173.078011] [<ffffffff8118b8b5>] kmem_cache_alloc_trace+0x105/0x2a0
[ 173.078015] [<ffffffff8121c502>] sysfs_open_file+0x1e2/0x240
[ 173.078021] [<ffffffff811a232b>] do_dentry_open+0x1fb/0x290
[ 173.078025] [<ffffffff811a2400>] finish_open+0x40/0x50
[ 173.078029] [<ffffffff811b3c9a>] do_last+0x4ca/0xe00
[ 173.078033] [<ffffffff811b468e>] path_openat+0xbe/0x6f0
[ 173.078037] [<ffffffff811b539a>] do_filp_open+0x3a/0x90
[ 173.078040] [<ffffffff811a37ee>] do_sys_open+0x12e/0x210
[ 173.078045] [<ffffffff811a38ee>] SyS_open+0x1e/0x20
[ 173.078049] [<ffffffff81597106>] system_call_fastpath+0x1a/0x1f
[ 173.078053]
-> #0 ((&req.work)){+.+...}:
[ 173.078060] [<ffffffff810bcac0>] __lock_acquire+0x1790/0x1af0
[ 173.078063] [<ffffffff810bd5e3>] lock_acquire+0x93/0x200
[ 173.078067] [<ffffffff81067946>] flush_work+0x36/0x60
[ 173.078071] [<ffffffffa0a72748>] chunk_io+0x118/0x150 [dm_snapshot]
[ 173.078076] [<ffffffffa0a727d9>] write_header+0x59/0x60 [dm_snapshot]
[ 173.078081] [<ffffffffa0a727f9>] persistent_drop_snapshot+0x19/0x30
[dm_snapshot]
[ 173.078086] [<ffffffffa0a6fe9c>]
__invalidate_snapshot.part.13+0x2c/0x70 [dm_snapshot]
[ 173.078091] [<ffffffffa0a719b7>] snapshot_map+0x127/0x3a0 [dm_snapshot]
[ 173.078096] [<ffffffffa0a4e7ee>] __map_bio+0x3e/0x1f0 [dm_mod]
[ 173.078104] [<ffffffffa0a4eb80>]
__clone_and_map_data_bio+0x150/0x230 [dm_mod]
[ 173.078109] [<ffffffffa0a4f08c>] __split_and_process_bio+0x38c/0x5a0
[dm_mod]
[ 173.078115] [<ffffffffa0a4f5a9>] dm_request+0x1b9/0x2f0 [dm_mod]
[ 173.078121] [<ffffffff813042b2>] generic_make_request+0xc2/0x110
[ 173.078127] [<ffffffff81304362>] submit_bio+0x62/0x130
[ 173.078131] [<ffffffff811e7ac8>] __mpage_writepage+0x448/0x680
[ 173.078136] [<ffffffff8114931b>] write_cache_pages+0x27b/0x630
[ 173.078142] [<ffffffff811e763a>] mpage_writepages+0x5a/0xa0
[ 173.078146] [<ffffffff812429d5>] ext2_writepages+0x15/0x20
[ 173.078151] [<ffffffff8114b081>] do_writepages+0x21/0x50
[ 173.078155] [<ffffffff811d27d0>] __writeback_single_inode+0x40/0x600
[ 173.078160] [<ffffffff811d3000>] writeback_sb_inodes+0x270/0x570
[ 173.078164] [<ffffffff811d339f>] __writeback_inodes_wb+0x9f/0xd0
[ 173.078168] [<ffffffff811d3743>] wb_writeback+0x373/0x5a0
[ 173.078172] [<ffffffff811d4094>] bdi_writeback_workfn+0x134/0x6d0
[ 173.078176] [<ffffffff8106993d>] process_one_work+0x1fd/0x6f0
[ 173.078180] [<ffffffff81069f53>] worker_thread+0x123/0x3b0
[ 173.078184] [<ffffffff81074a0e>] kthread+0xde/0xf0
[ 173.078188] [<ffffffff8159705c>] ret_from_fork+0x7c/0xb0
[ 173.078192]
other info that might help us debug this:
[ 173.078196] Possible unsafe locking scenario:
[ 173.078198] CPU0 CPU1
[ 173.078200] ---- ----
[ 173.078202] lock(&s->lock);
[ 173.078207] lock((&req.work));
[ 173.078211] lock(&s->lock);
[ 173.078215] lock((&req.work));
[ 173.078219]
*** DEADLOCK ***
[ 173.078222] 5 locks held by kworker/u4:3/50:
[ 173.078225] #0: (writeback){++++.+}, at: [<ffffffff810698db>]
process_one_work+0x19b/0x6f0
[ 173.078233] #1: ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff810698db>]
process_one_work+0x19b/0x6f0
[ 173.078242] #2: (&type->s_umount_key#30){++++..}, at:
[<ffffffff811a7f64>] grab_super_passive+0x44/0x90
[ 173.078252] #3: (&md->io_barrier){.+.+..}, at: [<ffffffffa0a4f335>]
dm_get_live_table+0x5/0xc0 [dm_mod]
[ 173.078263] #4: (&s->lock){++++..}, at: [<ffffffffa0a71b3a>]
snapshot_map+0x2aa/0x3a0 [dm_snapshot]
[ 173.078273]
stack backtrace:
[ 173.078277] CPU: 0 PID: 50 Comm: kworker/u4:3 Not tainted
3.11.0-rc6-00153-gf4c4c6a #160
[ 173.078280] Hardware name: LENOVO 6464CTO/6464CTO, BIOS 7LETC9WW (2.29 )
03/18/2011
[ 173.078284] Workqueue: writeback bdi_writeback_workfn (flush-253:3)
[ 173.078289] ffffffff82369540 ffff8801305732f8 ffffffff815869ad
ffffffff82369540
[ 173.078295] ffff880130573338 ffffffff815827ab ffff880130573390
ffff880130ab4ef8
[ 173.078301] 0000000000000004 ffff880130ab4ec0 ffff880130ab46e0
ffff880130ab4ef8
[ 173.078307] Call Trace:
[ 173.078312] [<ffffffff815869ad>] dump_stack+0x4e/0x82
[ 173.078317] [<ffffffff815827ab>] print_circular_bug+0x200/0x20f
[ 173.078322] [<ffffffff810bcac0>] __lock_acquire+0x1790/0x1af0
[ 173.078326] [<ffffffff810b78df>] ? trace_hardirqs_off_caller+0x1f/0xc0
[ 173.078330] [<ffffffff810b8089>] ? put_lock_stats.isra.27+0x29/0x40
[ 173.078334] [<ffffffff810bd5e3>] lock_acquire+0x93/0x200
[ 173.078338] [<ffffffff81067915>] ? flush_work+0x5/0x60
[ 173.078342] [<ffffffff81067946>] flush_work+0x36/0x60
[ 173.078346] [<ffffffff81067915>] ? flush_work+0x5/0x60
[ 173.078351] [<ffffffffa0a72748>] chunk_io+0x118/0x150 [dm_snapshot]
[ 173.078357] [<ffffffffa0a72600>] ? persistent_prepare_exception+0xa0/0xa0
[dm_snapshot]
[ 173.078363] [<ffffffffa0a727d9>] write_header+0x59/0x60 [dm_snapshot]
[ 173.078368] [<ffffffffa0a727f9>] persistent_drop_snapshot+0x19/0x30
[dm_snapshot]
[ 173.078373] [<ffffffffa0a6fe9c>] __invalidate_snapshot.part.13+0x2c/0x70
[dm_snapshot]
[ 173.078378] [<ffffffffa0a719b7>] snapshot_map+0x127/0x3a0 [dm_snapshot]
[ 173.078384] [<ffffffffa0a4e7ee>] __map_bio+0x3e/0x1f0 [dm_mod]
[ 173.078391] [<ffffffffa0a4eb80>] __clone_and_map_data_bio+0x150/0x230 [dm_mod]
[ 173.078397] [<ffffffffa0a4f08c>] __split_and_process_bio+0x38c/0x5a0 [dm_mod]
[ 173.078404] [<ffffffffa0a4f5a9>] dm_request+0x1b9/0x2f0 [dm_mod]
[ 173.078410] [<ffffffffa0a4f425>] ? dm_request+0x35/0x2f0 [dm_mod]
[ 173.078414] [<ffffffff813042b2>] generic_make_request+0xc2/0x110
[ 173.078419] [<ffffffff81304362>] submit_bio+0x62/0x130
[ 173.078423] [<ffffffff811e7ac8>] __mpage_writepage+0x448/0x680
[ 173.078429] [<ffffffff81084c2d>] ? get_parent_ip+0xd/0x50
[ 173.078433] [<ffffffff810baddb>] ? mark_held_locks+0xbb/0x140
[ 173.078438] [<ffffffff8114906c>] ? clear_page_dirty_for_io+0xac/0xe0
[ 173.078442] [<ffffffff810baf75>] ? trace_hardirqs_on_caller+0x115/0x1e0
[ 173.078446] [<ffffffff8114931b>] write_cache_pages+0x27b/0x630
[ 173.078450] [<ffffffff810ba933>] ? check_irq_usage+0x83/0xc0
[ 173.078455] [<ffffffff811e7680>] ? mpage_writepages+0xa0/0xa0
[ 173.078459] [<ffffffff81243620>] ? ext2_get_blocks+0xa90/0xa90
[ 173.078463] [<ffffffff811e763a>] mpage_writepages+0x5a/0xa0
[ 173.078467] [<ffffffff81243620>] ? ext2_get_blocks+0xa90/0xa90
[ 173.078472] [<ffffffff812429d5>] ext2_writepages+0x15/0x20
[ 173.078476] [<ffffffff8114b081>] do_writepages+0x21/0x50
[ 173.078481] [<ffffffff811d27d0>] __writeback_single_inode+0x40/0x600
[ 173.078485] [<ffffffff811d3000>] writeback_sb_inodes+0x270/0x570
[ 173.078489] [<ffffffff811d339f>] __writeback_inodes_wb+0x9f/0xd0
[ 173.078494] [<ffffffff811d3743>] wb_writeback+0x373/0x5a0
[ 173.078498] [<ffffffff811d4094>] bdi_writeback_workfn+0x134/0x6d0
[ 173.078503] [<ffffffff810698db>] ? process_one_work+0x19b/0x6f0
[ 173.078507] [<ffffffff8106993d>] process_one_work+0x1fd/0x6f0
[ 173.078511] [<ffffffff810698db>] ? process_one_work+0x19b/0x6f0
[ 173.078515] [<ffffffff81069f53>] worker_thread+0x123/0x3b0
[ 173.078519] [<ffffffff81069e30>] ? process_one_work+0x6f0/0x6f0
[ 173.078523] [<ffffffff81074a0e>] kthread+0xde/0xf0
[ 173.078529] [<ffffffff81074930>] ? insert_kthread_work+0x70/0x70
[ 173.078532] [<ffffffff8159705c>] ret_from_fork+0x7c/0xb0
[ 173.078537] [<ffffffff81074930>] ? insert_kthread_work+0x70/0x70
[ 173.120355] quiet_error: 1206 callbacks suppressed
[ 173.120362] Buffer I/O error on device dm-3, logical block 34
next prev parent reply other threads:[~2013-09-18 6:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-17 20:47 [PATCH] dm-snapshot: workaround for a lockdep warning Mikulas Patocka
2013-09-17 23:24 ` Mikulas Patocka
2013-09-18 0:08 ` Mikulas Patocka
2013-09-18 6:57 ` Zdenek Kabelac [this message]
2013-09-18 15:57 ` Mikulas Patocka
2013-09-18 19:07 ` Zdenek Kabelac
2013-09-18 23:14 ` Mikulas Patocka
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