Re: [RFC] fs: Avoid to use lockdep information if it's turned off

Boqun Feng
2020-11-12T05:36:06Z

Hi David,

On Wed, Nov 11, 2020 at 03:01:21PM +0100, David Sterba wrote:
> On Tue, Nov 10, 2020 at 04:33:27PM +0100, David Sterba wrote:
> > On Tue, Nov 10, 2020 at 09:37:37AM +0800, Boqun Feng wrote:
> >
> > I'll run another test on top of the development branch in case there are
> > unrelated lockdep warning bugs that have been fixed meanwhile.
>
> Similar reports but earlier test and probably completely valid due to
> "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"
>

Thanks for trying this out. These results are as expected: first a
lockdep splat warning is hit, which could be either caused by the
detection of a deadlock case or caused by an internal lockdep issue
("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" in this case), the lockdep
get turned off afterwards, and then when __sb_start_write() wants to use
lock holding information, we find out, stop using that information and
do a WARN_ON_ONCE().

Without this patch, __sb_start_write() will get incorrect lock holding
information, and result in task hanging as reported by Filipe. Darrick's
patch:

https://lore.kernel.org/linux-fsdevel/160494580419.772573.9286165021627298770.stgit@magnolia/T/#t

can also fix that by not relying the lock holding information at all in
__sb_start_write(). And I think that's a better fix.

For the "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" warning, do you see
that every time when you run xfstests and don't see other lockdep
splats? If so, that means we reach the limitation of number of lockdep
hlock chains, and we should fix that.

Regards,
Boqun

> btrfs/057 [16:01:29][ 1580.146087] run fstests btrfs/057 at 2020-11-10 16:01:29
> [ 1580.787867] BTRFS info (device vda): disk space caching is enabled
> [ 1580.789366] BTRFS info (device vda): has skinny extents
> [ 1581.052542] BTRFS: device fsid 84018822-2e45-4341-80be-da6d2b4e033a devid 1 transid 5 /dev/vdb scanned by mkfs.btrfs (18739)
> [ 1581.105177] BTRFS info (device vdb): turning on sync discard
> [ 1581.106834] BTRFS info (device vdb): disk space caching is enabled
> [ 1581.108423] BTRFS info (device vdb): has skinny extents
> [ 1581.109799] BTRFS info (device vdb): flagging fs with big metadata feature
> [ 1581.120343] BTRFS info (device vdb): checking UUID tree
> [ 1586.942699] BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!
> [ 1586.945725] turning off the locking correctness validator.
> [ 1586.948823] Please attach the output of /proc/lock_stat to the bug report
> [ 1586.952153] CPU: 0 PID: 18771 Comm: fsstress Not tainted 5.10.0-rc3-default+ #1355
> [ 1586.954919] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
> [ 1586.958630] Call Trace:
> [ 1586.959214] dump_stack+0x77/0x97
> [ 1586.960030] add_chain_cache.cold+0x29/0x30
> [ 1586.961028] validate_chain+0x278/0x780
> [ 1586.961979] __lock_acquire+0x3fb/0x730
> [ 1586.962880] lock_acquire.part.0+0xac/0x1a0
> [ 1586.963895] ? try_to_wake_up+0x59/0x450
> [ 1586.965153] ? rcu_read_lock_sched_held+0x3f/0x70
> [ 1586.966569] ? lock_acquire+0xc4/0x150
> [ 1586.967699] ? try_to_wake_up+0x59/0x450
> [ 1586.968882] _raw_spin_lock_irqsave+0x43/0x90
> [ 1586.970207] ? try_to_wake_up+0x59/0x450
> [ 1586.971404] try_to_wake_up+0x59/0x450
> [ 1586.973149] wake_up_q+0x60/0xb0
> [ 1586.974620] __up_write+0x117/0x1d0
> [ 1586.975080] ------------[ cut here ]------------
> [ 1586.976039] btrfs_release_path+0xc8/0x180 [btrfs]
> [ 1586.977718] WARNING: CPU: 2 PID: 18772 at fs/super.c:1676 __sb_start_write+0x113/0x2a0
> [ 1586.979478] __btrfs_update_delayed_inode+0x1c1/0x2c0 [btrfs]
> [ 1586.979506] btrfs_commit_inode_delayed_inode+0x115/0x120 [btrfs]
> [ 1586.982484] Modules linked in:
> [ 1586.984080] btrfs_evict_inode+0x1e2/0x370 [btrfs]
> [ 1586.985557] dm_flakey
> [ 1586.986419] ? evict+0xc3/0x220
> [ 1586.986421] evict+0xd5/0x220
> [ 1586.986423] vfs_rmdir.part.0+0x10c/0x180
> [ 1586.986426] do_rmdir+0x14b/0x1b0
> [ 1586.987504] dm_mod
> [ 1586.988244] do_syscall_64+0x2d/0x70
> [ 1586.988947] xxhash_generic btrfs
> [ 1586.989779] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 1586.990906] blake2b_generic
> [ 1586.991808] RIP: 0033:0x7f0ad919b5d7
> [ 1586.992451] libcrc32c
> [ 1586.993427] Code: 73 01 c3 48 8b 0d 99 f8 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 54 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 69 f8 0c 00 f7 d8 64 89 01 48
> [ 1586.994380] crc32c_intel
> [ 1586.995546] RSP: 002b:00007ffc152bf368 EFLAGS: 00000202 ORIG_RAX: 0000000000000054
> [ 1586.996034] xor
> [ 1586.996613] RAX: ffffffffffffffda RBX: 00000000000001f4 RCX: 00007f0ad919b5d7
> [ 1586.996615] RDX: 0000000000316264 RSI: 0000000000000000 RDI: 000000000045eff0
> [ 1586.997033] zstd_decompress
> [ 1587.001060] RBP: 00007ffc152bf4b0 R08: 000000000045eff0 R09: 00007ffc152bf4a4
> [ 1587.001061] R10: 00000000000000b1 R11: 0000000000000202 R12: 000000000000030e
> [ 1587.001062] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> [ 1587.013639] zstd_compress xxhash lzo_compress lzo_decompress raid6_pq loop
> [ 1587.015763] CPU: 2 PID: 18772 Comm: fsstress Not tainted 5.10.0-rc3-default+ #1355
> [ 1587.017719] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
> [ 1587.020878] RIP: 0010:__sb_start_write+0x113/0x2a0
> [ 1587.022233] Code: f3 f8 da 58 85 c0 0f 84 95 01 00 00 40 84 ed 0f 85 4c 01 00 00 45 84 e4 0f 85 75 01 00 00 5b 44 89 e8 5d 41 5c 41 5d 41 5e c3 <0f> 0b 48 89 e8 31 d2 be 31 00 00 00 48 c7 c7 ca 98 e4 a7 48 c1 e0
> [ 1587.027309] RSP: 0018:ffffafbac3c2fdd0 EFLAGS: 00010246
> [ 1587.028998] RAX: 0000000000000001 RBX: ffffa320cc6b4478 RCX: 0000000000000000
> [ 1587.031038] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffa320cc6b4478
> [ 1587.032905] RBP: 0000000000000003 R08: 00000000000001b8 R09: ffffa320dbfa9b88
> [ 1587.035782] R10: 0000000000000001 R11: ffffffffff9bcd99 R12: 0000000000000001
> [ 1587.037974] R13: ffffa320cc6b4398 R14: ffffa320cc6b4698 R15: ffffa320e06f4000
> [ 1587.040473] FS: 00007f0ad90a7b80(0000) GS:ffffa3213da00000(0000) knlGS:0000000000000000
> [ 1587.043694] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1587.045577] CR2: 00000000007b5ce8 CR3: 0000000004be6006 CR4: 0000000000170ea0
> [ 1587.047744] Call Trace:
> [ 1587.048689] start_transaction+0x406/0x510 [btrfs]
> [ 1587.050009] btrfs_unlink+0x31/0xf0 [btrfs]
> [ 1587.051313] vfs_unlink+0xee/0x1d0
> [ 1587.052435] do_unlinkat+0x1a1/0x2e0
> [ 1587.053676] do_syscall_64+0x2d/0x70
> [ 1587.054883] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 1587.056428] RIP: 0033:0x7f0ad919b577
> [ 1587.057583] Code: f0 ff ff 73 01 c3 48 8b 0d f6 f8 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c9 f8 0c 00 f7 d8 64 89 01 48
> [ 1587.061252] RSP: 002b:00007ffc152bf358 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
> [ 1587.063942] RAX: ffffffffffffffda RBX: 00000000000001f4 RCX: 00007f0ad919b577
> [ 1587.065661] RDX: 0000000000643266 RSI: 0000000000000000 RDI: 0000000000418070
> [ 1587.067478] RBP: 00007ffc152bf4b0 R08: 0000000000418070 R09: 00007ffc152bf49c
> [ 1587.069024] R10: 000000000000002d R11: 0000000000000206 R12: 000000000000033e
> [ 1587.071631] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> [ 1587.074260] CPU: 2 PID: 18772 Comm: fsstress Not tainted 5.10.0-rc3-default+ #1355
> [ 1587.076198] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
> [ 1587.078659] Call Trace:
> [ 1587.079296] dump_stack+0x77/0x97
> [ 1587.080076] ? __sb_start_write+0x113/0x2a0
> [ 1587.081008] __warn.cold+0x24/0x83
> [ 1587.082506] ? __sb_start_write+0x113/0x2a0
> [ 1587.084716] report_bug+0x9a/0xc0
> [ 1587.086153] handle_bug+0x3c/0x60
> [ 1587.087103] exc_invalid_op+0x14/0x70
> [ 1587.087923] asm_exc_invalid_op+0x12/0x20
> [ 1587.088813] RIP: 0010:__sb_start_write+0x113/0x2a0
> [ 1587.089962] Code: f3 f8 da 58 85 c0 0f 84 95 01 00 00 40 84 ed 0f 85 4c 01 00 00 45 84 e4 0f 85 75 01 00 00 5b 44 89 e8 5d 41 5c 41 5d 41 5e c3 <0f> 0b 48 89 e8 31 d2 be 31 00 00 00 48 c7 c7 ca 98 e4 a7 48 c1 e0
> [ 1587.096163] RSP: 0018:ffffafbac3c2fdd0 EFLAGS: 00010246
> [ 1587.098068] RAX: 0000000000000001 RBX: ffffa320cc6b4478 RCX: 0000000000000000
> [ 1587.100489] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffa320cc6b4478
> [ 1587.102454] RBP: 0000000000000003 R08: 00000000000001b8 R09: ffffa320dbfa9b88
> [ 1587.103974] R10: 0000000000000001 R11: ffffffffff9bcd99 R12: 0000000000000001
> [ 1587.105366] R13: ffffa320cc6b4398 R14: ffffa320cc6b4698 R15: ffffa320e06f4000
> [ 1587.106873] start_transaction+0x406/0x510 [btrfs]
> [ 1587.107859] btrfs_unlink+0x31/0xf0 [btrfs]
> [ 1587.108735] vfs_unlink+0xee/0x1d0
> [ 1587.109451] do_unlinkat+0x1a1/0x2e0
> [ 1587.110387] do_syscall_64+0x2d/0x70
> [ 1587.111318] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 1587.112588] RIP: 0033:0x7f0ad919b577
> [ 1587.113543] Code: f0 ff ff 73 01 c3 48 8b 0d f6 f8 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c9 f8 0c 00 f7 d8 64 89 01 48
> [ 1587.117977] RSP: 002b:00007ffc152bf358 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
> [ 1587.119801] RAX: ffffffffffffffda RBX: 00000000000001f4 RCX: 00007f0ad919b577
> [ 1587.121488] RDX: 0000000000643266 RSI: 0000000000000000 RDI: 0000000000418070
> [ 1587.123213] RBP: 00007ffc152bf4b0 R08: 0000000000418070 R09: 00007ffc152bf49c
> [ 1587.124927] R10: 000000000000002d R11: 0000000000000206 R12: 000000000000033e
> [ 1587.126121] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> [ 1587.127122] irq event stamp: 1024932
> [ 1587.128395] hardirqs last enabled at (1024931): [<ffffffffa77fba04>] _raw_spin_unlock_irq+0x24/0x50
> [ 1587.131643] hardirqs last disabled at (1024932): [<ffffffffa77f4188>] __schedule+0x3d8/0x8a0
> [ 1587.135136] softirqs last enabled at (1024750): [<ffffffffa7a00333>] __do_softirq+0x333/0x5c2
> [ 1587.138237] softirqs last disabled at (1024741): [<ffffffffa7800dbf>] asm_call_irq_on_stack+0xf/0x20
> [ 1587.140456] ---[ end trace 6b74e3ebe67d602c ]---
> [ 1596.516828] BTRFS warning (device vdb): qgroup rescan is already in progress
> [ 1596.788296] BTRFS info (device vdb): qgroup scan completed (inconsistency flag cleared)
> [ 1597.641295] BTRFS info (device vdb): turning on sync discard
> [ 1597.644117] BTRFS info (device vdb): disk space caching is enabled
> [ 1597.646713] BTRFS info (device vdb): has skinny extents
> _check_dmesg: something found in dmesg (see /tmp/fstests/results//btrfs/057.dmesg)
> [16:01:46]
> btrfs/058 [16:01:46][ 1597.762062] run fstests btrfs/058 at 2020-11-10 16:01:46
> [ 1598.091148] BTRFS info (device vda): disk space caching is enabled
> [ 1598.093031] BTRFS info (device vda): has skinny extents
> [ 1598.168010] ------------[ cut here ]------------
> [ 1598.170209] WARNING: CPU: 1 PID: 19058 at fs/super.c:1676 __sb_start_write+0x113/0x2a0
> [ 1598.173471] Modules linked in: dm_flakey dm_mod xxhash_generic btrfs blake2b_generic libcrc32c crc32c_intel xor zstd_decompress zstd_compress xxhash lzo_compress lzo_decompress raid6_pq loop
> [ 1598.179110] CPU: 1 PID: 19058 Comm: xfs_io Tainted: G W 5.10.0-rc3-default+ #1355
> [ 1598.181745] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
> [ 1598.185018] RIP: 0010:__sb_start_write+0x113/0x2a0
> [ 1598.186490] Code: f3 f8 da 58 85 c0 0f 84 95 01 00 00 40 84 ed 0f 85 4c 01 00 00 45 84 e4 0f 85 75 01 00 00 5b 44 89 e8 5d 41 5c 41 5d 41 5e c3 <0f> 0b 48 89 e8 31 d2 be 31 00 00 00 48 c7 c7 ca 98 e4 a7 48 c1 e0
> [ 1598.191880] RSP: 0018:ffffafbac3ee7c38 EFLAGS: 00010246
> [ 1598.193397] RAX: 0000000000000001 RBX: ffffa320cfcdc478 RCX: 0000000000000000
> [ 1598.195124] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffa320cfcdc478
> [ 1598.197034] RBP: 0000000000000003 R08: 00000000000001b8 R09: ffffa320dbfa8378
> [ 1598.198974] R10: 0000000000000001 R11: 4548530074736574 R12: 0000000000000001
> [ 1598.200876] R13: ffffa320cfcdc398 R14: ffffa320cfcdc698 R15: ffffa320dade8000
> [ 1598.202775] FS: 00007fb5ad735e80(0000) GS:ffffa3213d800000(0000) knlGS:0000000000000000
> [ 1598.205041] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1598.206551] CR2: 00007fb5ad84d520 CR3: 000000000fc4c004 CR4: 0000000000170ea0
> [ 1598.208075] Call Trace:
> [ 1598.208707] start_transaction+0x406/0x510 [btrfs]
> [ 1598.209821] btrfs_tmpfile+0x49/0x1e0 [btrfs]
> [ 1598.210881] ? _raw_spin_unlock+0x29/0x40
> [ 1598.211841] vfs_tmpfile+0x63/0xe0
> [ 1598.212617] do_tmpfile+0x58/0xf0
> [ 1598.213355] path_openat+0x115/0x1b0
> [ 1598.214205] ? getname_flags+0x29/0x180
> [ 1598.215050] do_filp_open+0x88/0x130
> [ 1598.215883] ? lock_release+0xb0/0x160
> [ 1598.216793] ? do_raw_spin_unlock+0x4b/0xa0
> [ 1598.217741] ? _raw_spin_unlock+0x29/0x40
> [ 1598.218660] ? __alloc_fd+0xfc/0x1e0
> [ 1598.219478] do_sys_openat2+0x97/0x150
> [ 1598.220342] __x64_sys_openat+0x54/0x90
> [ 1598.221240] do_syscall_64+0x2d/0x70
> [ 1598.222027] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 1598.223057] RIP: 0033:0x7fb5ad980047
> [ 1598.223913] Code: 25 00 00 41 00 3d 00 00 41 00 74 47 64 8b 04 25 18 00 00 00 85 c0 75 6b 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 95 00 00 00 48 8b 4c 24 28 64 48 2b 0c 25
> [ 1598.228002] RSP: 002b:00007ffd74683120 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> [ 1598.230150] RAX: ffffffffffffffda RBX: 0000000000410002 RCX: 00007fb5ad980047
> [ 1598.232082] RDX: 0000000000410002 RSI: 00007ffd74684138 RDI: 00000000ffffff9c
> [ 1598.234054] RBP: 00007ffd74684138 R08: 0000000000000001 R09: 0000000000000000
> [ 1598.236003] R10: 0000000000000180 R11: 0000000000000246 R12: 0000000000410002
> [ 1598.237974] R13: 00007ffd74683510 R14: 0000000000000180 R15: 0000000000000200
> [ 1598.239945] CPU: 1 PID: 19058 Comm: xfs_io Tainted: G W 5.10.0-rc3-default+ #1355
> [ 1598.242186] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
> [ 1598.244585] Call Trace:
> [ 1598.245162] dump_stack+0x77/0x97
> [ 1598.245952] ? __sb_start_write+0x113/0x2a0
> [ 1598.246869] __warn.cold+0x24/0x83
> [ 1598.247614] ? __sb_start_write+0x113/0x2a0
> [ 1598.248561] report_bug+0x9a/0xc0
> [ 1598.249340] handle_bug+0x3c/0x60
> [ 1598.250112] exc_invalid_op+0x14/0x70
> [ 1598.250949] asm_exc_invalid_op+0x12/0x20
> [ 1598.251844] RIP: 0010:__sb_start_write+0x113/0x2a0
> [ 1598.252862] Code: f3 f8 da 58 85 c0 0f 84 95 01 00 00 40 84 ed 0f 85 4c 01 00 00 45 84 e4 0f 85 75 01 00 00 5b 44 89 e8 5d 41 5c 41 5d 41 5e c3 <0f> 0b 48 89 e8 31 d2 be 31 00 00 00 48 c7 c7 ca 98 e4 a7 48 c1 e0
> [ 1598.256674] RSP: 0018:ffffafbac3ee7c38 EFLAGS: 00010246
> [ 1598.257786] RAX: 0000000000000001 RBX: ffffa320cfcdc478 RCX: 0000000000000000
> [ 1598.259554] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffa320cfcdc478
> [ 1598.261376] RBP: 0000000000000003 R08: 00000000000001b8 R09: ffffa320dbfa8378
> [ 1598.263173] R10: 0000000000000001 R11: 4548530074736574 R12: 0000000000000001
> [ 1598.264966] R13: ffffa320cfcdc398 R14: ffffa320cfcdc698 R15: ffffa320dade8000
> [ 1598.266774] ? __sb_start_write+0x68/0x2a0
> [ 1598.267888] start_transaction+0x406/0x510 [btrfs]
> [ 1598.269165] btrfs_tmpfile+0x49/0x1e0 [btrfs]
> [ 1598.270350] ? _raw_spin_unlock+0x29/0x40
> [ 1598.271421] vfs_tmpfile+0x63/0xe0
> [ 1598.272361] do_tmpfile+0x58/0xf0
> [ 1598.273281] path_openat+0x115/0x1b0
> [ 1598.274230] ? getname_flags+0x29/0x180
> [ 1598.275082] do_filp_open+0x88/0x130
> [ 1598.275879] ? lock_release+0xb0/0x160
> [ 1598.276706] ? do_raw_spin_unlock+0x4b/0xa0
> [ 1598.277923] ? _raw_spin_unlock+0x29/0x40
> [ 1598.279328] ? __alloc_fd+0xfc/0x1e0
> [ 1598.280596] do_sys_openat2+0x97/0x150
> [ 1598.281922] __x64_sys_openat+0x54/0x90
> [ 1598.283179] do_syscall_64+0x2d/0x70
> [ 1598.284373] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 1598.285973] RIP: 0033:0x7fb5ad980047
> [ 1598.287187] Code: 25 00 00 41 00 3d 00 00 41 00 74 47 64 8b 04 25 18 00 00 00 85 c0 75 6b 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 95 00 00 00 48 8b 4c 24 28 64 48 2b 0c 25
> [ 1598.292907] RSP: 002b:00007ffd74683120 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> [ 1598.294685] RAX: ffffffffffffffda RBX: 0000000000410002 RCX: 00007fb5ad980047
> [ 1598.296442] RDX: 0000000000410002 RSI: 00007ffd74684138 RDI: 00000000ffffff9c
> [ 1598.298284] RBP: 00007ffd74684138 R08: 0000000000000001 R09: 0000000000000000
> [ 1598.300103] R10: 0000000000000180 R11: 0000000000000246 R12: 0000000000410002
> [ 1598.301922] R13: 00007ffd74683510 R14: 0000000000000180 R15: 0000000000000200
> [ 1598.303754] irq event stamp: 0
> [ 1598.304612] hardirqs last enabled at (0): [<0000000000000000>] 0x0
> [ 1598.306302] hardirqs last disabled at (0): [<ffffffffa707134b>] copy_process+0x3db/0x1440
> [ 1598.308468] softirqs last enabled at (0): [<ffffffffa707134b>] copy_process+0x3db/0x1440
> [ 1598.310645] softirqs last disabled at (0): [<0000000000000000>] 0x0
> [ 1598.312198] ---[ end trace 6b74e3ebe67d602d ]---
> [ 1598.432274] BTRFS: device fsid 7c33f125-75b7-43f5-92a4-0fdbf15d7bef devid 1 transid 5 /dev/vdb scanned by mkfs.btrfs (19079)
> [ 1598.459998] BTRFS info (device vdb): turning on sync discard
> [ 1598.461401] BTRFS info (device vdb): disk space caching is enabled
> [ 1598.462886] BTRFS info (device vdb): has skinny extents
> [ 1598.464116] BTRFS info (device vdb): flagging fs with big metadata feature
> [ 1598.470328] BTRFS info (device vdb): checking UUID tree
> [ 1601.577163] BTRFS info (device vdb): turning on sync discard
> [ 1601.579595] BTRFS info (device vdb): disk space caching is enabled
> [ 1601.581907] BTRFS info (device vdb): has skinny extents
> _check_dmesg: something found in dmesg (see /tmp/fstests/results//btrfs/058.dmesg)
> [16:01:50]