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
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