INFO: task hung in __blkdev_put

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
e02d37bf55a9a36f22427fd6dd733fe104d817b6 (Thu Apr 5 17:42:07 2018 +0000)
Merge tag 'sound-4.17-rc1' of
git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=feea3dc291bb64479250

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=4806510911684608
Kernel config:
https://syzkaller.appspot.com/x/.config?id=-4805825610197092128
compiler: gcc (GCC) 8.0.1 20180301 (experimental)
CC: [ak...@linux-foundation.org arya...@virtuozzo.com ja...@suse.cz
jla...@redhat.com linux-...@vger.kernel.org linu...@kvack.org
mgo...@techsingularity.net rgol...@suse.com vi...@zeniv.linux.org.uk]

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+feea3d...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.

Buffer I/O error on dev loop0, logical block 6, lost async page write
Buffer I/O error on dev loop0, logical block 7, lost async page write
Buffer I/O error on dev loop0, logical block 8, lost async page write
Buffer I/O error on dev loop0, logical block 9, lost async page write
bond0 (unregistering): Released all slaves
INFO: task syz-executor7:24317 blocked for more than 120 seconds.
Not tainted 4.16.0+ #2
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7 D18880 24317 4522 0x80000006
Call Trace:
context_switch kernel/sched/core.c:2848 [inline]
__schedule+0x807/0x1e40 kernel/sched/core.c:3490
schedule+0xef/0x430 kernel/sched/core.c:3549
io_schedule+0x1c/0x70 kernel/sched/core.c:5169
wait_on_page_bit_common+0x4dc/0x770 mm/filemap.c:1099
wait_on_page_bit mm/filemap.c:1132 [inline]
wait_on_page_writeback include/linux/pagemap.h:546 [inline]
__filemap_fdatawait_range+0x31e/0x4c0 mm/filemap.c:533
filemap_fdatawait_range mm/filemap.c:558 [inline]
filemap_fdatawait include/linux/fs.h:2591 [inline]
filemap_write_and_wait+0x93/0x100 mm/filemap.c:624
__sync_blockdev fs/block_dev.c:448 [inline]
sync_blockdev fs/block_dev.c:457 [inline]
__blkdev_put+0x202/0x830 fs/block_dev.c:1781
blkdev_put+0x98/0x540 fs/block_dev.c:1850
blkdev_close+0x8b/0xb0 fs/block_dev.c:1857
__fput+0x34d/0x890 fs/file_table.c:209
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x1e4/0x290 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x1aee/0x2730 kernel/exit.c:865
do_group_exit+0x16f/0x430 kernel/exit.c:968
get_signal+0x886/0x1960 kernel/signal.c:2469
do_signal+0x90/0x2020 arch/x86/kernel/signal.c:810
exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
do_syscall_64+0x792/0x9d0 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4552d9
RSP: 002b:00007f026fd78c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: 0000000000041000 RBX: 00007f026fd796d4 RCX: 00000000004552d9
RDX: 00000000200ddff8 RSI: 0000000000000014 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000102000001 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000004c5 R14: 00000000006fa318 R15: 0000000000000000

Showing all locks held in the system:
3 locks held by kworker/u4:3/158:
#0: 00000000253d20ca ((wq_completion)"writeback"){+.+.}, at:
__write_once_size include/linux/compiler.h:215 [inline]
#0: 00000000253d20ca ((wq_completion)"writeback"){+.+.}, at:
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: 00000000253d20ca ((wq_completion)"writeback"){+.+.}, at: atomic64_set
include/asm-generic/atomic-instrumented.h:40 [inline]
#0: 00000000253d20ca ((wq_completion)"writeback"){+.+.}, at:
atomic_long_set include/asm-generic/atomic-long.h:57 [inline]
#0: 00000000253d20ca ((wq_completion)"writeback"){+.+.}, at: set_work_data
kernel/workqueue.c:617 [inline]
#0: 00000000253d20ca ((wq_completion)"writeback"){+.+.}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
#0: 00000000253d20ca ((wq_completion)"writeback"){+.+.}, at:
process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116
#1: 00000000b18c7d3f ((work_completion)(&(&wb->dwork)->work)){+.+.}, at:
process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120
#2: 00000000e6930f16 (&type->s_umount_key#35){++++}, at:
trylock_super+0x22/0x110 fs/super.c:395
2 locks held by khungtaskd/878:
#0: 00000000ecd7e36e (rcu_read_lock){....}, at:
check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
#0: 00000000ecd7e36e (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60
kernel/hung_task.c:249
#1: 00000000fe0e8cb6 (tasklist_lock){.+.+}, at:
debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470
1 lock held by rsyslogd/4350:
#0: 00000000a77bbab4 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0
fs/file.c:766
2 locks held by getty/4440:
#0: 00000000bab03177 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: 000000009aa3f262 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4441:
#0: 00000000c8280840 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: 000000008caf5ecd (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4442:
#0: 000000004e356e55 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: 0000000088b85d7e (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4443:
#0: 00000000fc495381 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: 000000008b927eaf (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4444:
#0: 0000000061a08d89 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: 000000003fc2ab62 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4445:
#0: 00000000ade31f7a (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: 00000000ed5c5ca8 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4446:
#0: 00000000129c9188 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: 000000003003dbfd (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
1 lock held by syz-executor7/24317:
#0: 00000000e635ddec (&bdev->bd_mutex){+.+.}, at: __blkdev_put+0xc2/0x830
fs/block_dev.c:1775
1 lock held by blkid/24394:
#0: 00000000e635ddec (&bdev->bd_mutex){+.+.}, at:
__blkdev_get+0x193/0x13a0 fs/block_dev.c:1458

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 878 Comm: khungtaskd Not tainted 4.16.0+ #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b9/0x29f lib/dump_stack.c:53
nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
check_hung_task kernel/hung_task.c:132 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
watchdog+0xc10/0xf60 kernel/hung_task.c:249
kthread+0x345/0x410 kernel/kthread.c:238
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.16.0+ #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:ktime_get+0x200/0x430 kernel/time/timekeeping.c:739
RSP: 0018:ffff8801db107b98 EFLAGS: 00000093
RAX: 0000008f473e99d6 RBX: ffffed003b620f7d RCX: ffffffff81666786
RDX: 0000000000000000 RSI: ffffffff81666799 RDI: 0000000000000005
RBP: ffff8801db107c90 R08: ffff8801d9ec8340 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000000 R12: dffffc0000000000
R13: 000000000009db52 R14: ffff8801db107c68 R15: ffffffff88b172a0
FS: 0000000000000000(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000001b365a000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
tick_nohz_irq_enter kernel/time/tick-sched.c:1133 [inline]
tick_irq_enter+0xbc/0x3f0 kernel/time/tick-sched.c:1154
irq_enter+0xb6/0xd0 kernel/softirq.c:346
scheduler_ipi+0x39b/0xa30 kernel/sched/core.c:1768
smp_reschedule_interrupt+0xed/0x660 arch/x86/kernel/smp.c:277
reschedule_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:886
</IRQ>
RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54
RSP: 0018:ffff8801d9ed7cb0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02
RAX: dffffc0000000000 RBX: 1ffff1003b3daf99 RCX: 0000000000000000
RDX: 1ffffffff1162e58 RSI: 0000000000000001 RDI: ffffffff88b172c0
RBP: ffff8801d9ed7cb0 R08: ffff8801d9ec8340 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffff8801d9ed7d68 R14: ffffffff88b172b0 R15: 0000000000000000
arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
default_idle+0xc2/0x440 arch/x86/kernel/process.c:354
arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:345
default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
cpuidle_idle_call kernel/sched/idle.c:151 [inline]
do_idle+0x2f4/0x3c0 kernel/sched/idle.c:241
cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:346
start_secondary+0x426/0x5b0 arch/x86/kernel/smpboot.c:267
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242
Code: f8 83 e2 01 89 d6 89 95 30 ff ff ff e8 aa 32 10 00 8b 95 30 ff ff ff
85 d2 0f 85 8f 01 00 00 e8 87 31 10 00 48 8b 05 f0 ff e4 08 <48> 89 85 20
ff ff ff 49 8d 46 c0 48 c1 e8 03 4c 01 e0 c6 00 00


---
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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.