INFO: task hung in snd_timer_close

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: a99d8080 Linux 5.4-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10afae68e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c5e2eca3f31f9bf
dashboard link: https://syzkaller.appspot.com/bug?extid=f1048ebddb93befb085f
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=126bc658e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f1048e...@syzkaller.appspotmail.com

INFO: task syz-executor.0:12251 blocked for more than 143 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D28160 12251 8868 0x00000004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
snd_timer_user_release+0x98/0x130 sound/core/timer.c:1478
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: c0 c3 0f 1f 80 00 00 00 00 c7 07 00 00 00 00 31 c0 c3 0f 1f 80 00 00
00 00 31 c0 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 b8 <2d> f8 ff ff c3
66 2e 0f 1f 84 00 00 00 00 00 31 c0 c3 66 66 66 66
RSP: 002b:00007ffdda4a34b0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413db1
RDX: 0000001b2dd20000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff
R10: 00007ffdda4a3590 R11: 0000000000000293 R12: 000000000075c9a0
R13: 000000000075c9a0 R14: 0000000000760a90 R15: 000000000075bf2c
INFO: task syz-executor.2:12256 blocked for more than 143 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2 D28160 12256 8864 0x00000004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
snd_timer_user_release+0x98/0x130 sound/core/timer.c:1478
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: c0 c3 0f 1f 80 00 00 00 00 c7 07 00 00 00 00 31 c0 c3 0f 1f 80 00 00
00 00 31 c0 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 b8 <2d> f8 ff ff c3
66 2e 0f 1f 84 00 00 00 00 00 31 c0 c3 66 66 66 66
RSP: 002b:00007ffe078ed7d0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413db1
RDX: 0000001b2da20000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff
R10: 00007ffe078ed8b0 R11: 0000000000000293 R12: 000000000075c9a0
R13: 000000000075c9a0 R14: 0000000000760a90 R15: 000000000075bf2c
INFO: task syz-executor.4:12266 blocked for more than 144 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D28480 12266 8871 0x00000004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_open+0x98/0x1860 sound/core/timer.c:245
snd_timer_user_tselect sound/core/timer.c:1728 [inline]
__snd_timer_user_ioctl.isra.0+0x68b/0x1fd0 sound/core/timer.c:2003
snd_timer_user_ioctl+0x7a/0xa7 sound/core/timer.c:2033
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.
RSP: 002b:00007f2806975c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a219
RDX: 0000000020029fcc RSI: 0000000040345410 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f28069766d4
R13: 00000000004cf428 R14: 00000000004d9760 R15: 00000000ffffffff
INFO: task syz-executor.4:12269 blocked for more than 144 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D29712 12269 8871 0x00000004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.
RSP: 002b:00007f2806954c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 000000000045a219
RDX: 0000000000000000 RSI: 00000000000054a0 RDI: 0000000000000003
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f28069556d4
R13: 00000000004c4ae8 R14: 00000000004d9778 R15: 00000000ffffffff
INFO: task syz-executor.4:12271 blocked for more than 144 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D28000 12271 8871 0x00000004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_open+0x98/0x1860 sound/core/timer.c:245
snd_seq_timer_open+0x240/0x590 sound/core/seq/seq_timer.c:275
queue_use+0xf1/0x270 sound/core/seq/seq_queue.c:489
snd_seq_queue_alloc+0x2c5/0x4d0 sound/core/seq/seq_queue.c:176
snd_seq_ioctl_create_queue+0xb0/0x330 sound/core/seq/seq_clientmgr.c:1548
snd_seq_kernel_client_ctl+0xf8/0x140 sound/core/seq/seq_clientmgr.c:2353
alloc_seq_queue.isra.0+0xdc/0x180 sound/core/seq/oss/seq_oss_init.c:357
snd_seq_oss_open+0x2ff/0x960 sound/core/seq/oss/seq_oss_init.c:215
odev_open+0x70/0x90 sound/core/seq/oss/seq_oss.c:125
soundcore_open+0x453/0x610 sound/sound_core.c:593
chrdev_open+0x245/0x6b0 fs/char_dev.c:414
do_dentry_open+0x4e6/0x1380 fs/open.c:797
vfs_open+0xa0/0xd0 fs/open.c:914
do_last fs/namei.c:3408 [inline]
path_openat+0x10e9/0x46d0 fs/namei.c:3525
do_filp_open+0x1a1/0x280 fs/namei.c:3555
do_sys_open+0x3fe/0x5d0 fs/open.c:1097
__do_sys_openat fs/open.c:1124 [inline]
__se_sys_openat fs/open.c:1118 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1118
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.
RSP: 002b:00007f2806933c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a219
RDX: 0000000000000001 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f28069346d4
R13: 00000000004c734a R14: 00000000004dcf88 R15: 00000000ffffffff
INFO: task syz-executor.4:12273 blocked for more than 145 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D28552 12273 8871 0x00000004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.
RSP: 002b:00007f2806912c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 000000000045a219
RDX: 0000000000000000 RSI: 00000000000054a0 RDI: 0000000000000003
RBP: 000000000075c118 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f28069136d4
R13: 00000000004c4ae8 R14: 00000000004d9778 R15: 00000000ffffffff
INFO: task syz-executor.4:12275 blocked for more than 145 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D29312 12275 8871 0x00004004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_open+0x98/0x1860 sound/core/timer.c:245
snd_timer_user_tselect sound/core/timer.c:1728 [inline]
__snd_timer_user_ioctl.isra.0+0x68b/0x1fd0 sound/core/timer.c:2003
snd_timer_user_ioctl+0x7a/0xa7 sound/core/timer.c:2033
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.
RSP: 002b:00007f28068f1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a219
RDX: 0000000020029fcc RSI: 0000000040345410 RDI: 0000000000000003
RBP: 000000000075c1c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f28068f26d4
R13: 00000000004cf428 R14: 00000000004d9760 R15: 00000000ffffffff
INFO: task syz-executor.4:12276 blocked for more than 146 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D28536 12276 8871 0x00004004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
odev_open+0x5f/0x90 sound/core/seq/oss/seq_oss.c:124
soundcore_open+0x453/0x610 sound/sound_core.c:593
chrdev_open+0x245/0x6b0 fs/char_dev.c:414
do_dentry_open+0x4e6/0x1380 fs/open.c:797
vfs_open+0xa0/0xd0 fs/open.c:914
do_last fs/namei.c:3408 [inline]
path_openat+0x10e9/0x46d0 fs/namei.c:3525
do_filp_open+0x1a1/0x280 fs/namei.c:3555
do_sys_open+0x3fe/0x5d0 fs/open.c:1097
__do_sys_openat fs/open.c:1124 [inline]
__se_sys_openat fs/open.c:1118 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1118
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.
RSP: 002b:00007f28068d0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a219
RDX: 0000000000000001 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 000000000075c268 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f28068d16d4
R13: 00000000004c734a R14: 00000000004dcf88 R15: 00000000ffffffff
INFO: task syz-executor.1:12261 blocked for more than 146 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1 D28160 12261 8866 0x00000004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
snd_timer_user_release+0x98/0x130 sound/core/timer.c:1478
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: c0 c3 0f 1f 80 00 00 00 00 c7 07 00 00 00 00 31 c0 c3 0f 1f 80 00 00
00 00 31 c0 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 b8 <2d> f8 ff ff c3
66 2e 0f 1f 84 00 00 00 00 00 31 c0 c3 66 66 66 66
RSP: 002b:00007ffe3503b380 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413db1
RDX: 0000001b2db20000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff
R10: 00007ffe3503b460 R11: 0000000000000293 R12: 000000000075c9a0
R13: 000000000075c9a0 R14: 0000000000760a90 R15: 000000000075bf2c
INFO: task syz-executor.5:12267 blocked for more than 147 seconds.
Not tainted 5.4.0-rc6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5 D28552 12267 8870 0x00000004
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_open+0x98/0x1860 sound/core/timer.c:245
snd_timer_user_tselect sound/core/timer.c:1728 [inline]
__snd_timer_user_ioctl.isra.0+0x68b/0x1fd0 sound/core/timer.c:2003
snd_timer_user_ioctl+0x7a/0xa7 sound/core/timer.c:2033
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.
RSP: 002b:00007ff76c742c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a219
RDX: 0000000020029fcc RSI: 0000000040345410 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff76c7436d4
R13: 00000000004cf428 R14: 00000000004d9760 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/1070:
#0: ffffffff88fab340 (rcu_read_lock){....}, at:
debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5337
1 lock held by rsyslogd/8724:
#0: ffff88809ae4bd60 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110
fs/file.c:801
2 locks held by getty/8813:
#0: ffff8880a459b090 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f152e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8814:
#0: ffff8880a9021090 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f212e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8815:
#0: ffff8880a818a090 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f192e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8816:
#0: ffff8880a843a090 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f1d2e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8817:
#0: ffff8880a2834090 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f252e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8818:
#0: ffff88809aafe090 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f292e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8819:
#0: ffff8880a514a090 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005ef12e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by syz-executor.3/12245:
2 locks held by syz-executor.0/12251:
#0: ffff888082e84550 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_release+0x67/0x130 sound/core/timer.c:1476
#1: ffffffff89914b00 (register_mutex){+.+.}, at:
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
2 locks held by syz-executor.2/12256:
#0: ffff88809c005150 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_release+0x67/0x130 sound/core/timer.c:1476
#1: ffffffff89914b00 (register_mutex){+.+.}, at:
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
2 locks held by syz-executor.4/12266:
#0: ffff8880a9b93950 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
#1: ffffffff89914b00 (register_mutex){+.+.}, at:
snd_timer_open+0x98/0x1860 sound/core/timer.c:245
1 lock held by syz-executor.4/12269:
#0: ffff8880a9b93950 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
2 locks held by syz-executor.4/12271:
#0: ffffffff89924320 (register_mutex#4){+.+.}, at: odev_open+0x5f/0x90
sound/core/seq/oss/seq_oss.c:124
#1: ffffffff89914b00 (register_mutex){+.+.}, at:
snd_timer_open+0x98/0x1860 sound/core/timer.c:245
1 lock held by syz-executor.4/12273:
#0: ffff888096c8d550 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
2 locks held by syz-executor.4/12275:
#0: ffff888096c8d550 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
#1: ffffffff89914b00 (register_mutex){+.+.}, at:
snd_timer_open+0x98/0x1860 sound/core/timer.c:245
1 lock held by syz-executor.4/12276:
#0: ffffffff89924320 (register_mutex#4){+.+.}, at: odev_open+0x5f/0x90
sound/core/seq/oss/seq_oss.c:124
2 locks held by syz-executor.1/12261:
#0: ffff88809a826950 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_release+0x67/0x130 sound/core/timer.c:1476
#1: ffffffff89914b00 (register_mutex){+.+.}, at:
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
2 locks held by syz-executor.5/12267:
#0: ffff8880970f0950 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
#1: ffffffff89914b00 (register_mutex){+.+.}, at:
snd_timer_open+0x98/0x1860 sound/core/timer.c:245
1 lock held by syz-executor.5/12270:
#0: ffff8880970f0950 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
1 lock held by syz-executor.5/12272:
#0: ffffffff89924320 (register_mutex#4){+.+.}, at: odev_open+0x5f/0x90
sound/core/seq/oss/seq_oss.c:124
1 lock held by syz-executor.5/12274:
#0: ffff8880a0113d50 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
2 locks held by syz-executor.5/12277:
#0: ffff8880a0113d50 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
#1: ffffffff89914b00 (register_mutex){+.+.}, at:
snd_timer_open+0x98/0x1860 sound/core/timer.c:245
1 lock held by syz-executor.5/12279:
#0: ffffffff89924320 (register_mutex#4){+.+.}, at: odev_open+0x5f/0x90
sound/core/seq/oss/seq_oss.c:124

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

NMI backtrace for cpu 1
CPU: 1 PID: 1070 Comm: khungtaskd Not tainted 5.4.0-rc6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
watchdog+0x9d0/0xef0 kernel/hung_task.c:289
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 12245 Comm: syz-executor.3 Not tainted 5.4.0-rc6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:rdtsc_ordered arch/x86/include/asm/msr.h:236 [inline]
RIP: 0010:delay_tsc+0x4a/0xc0 arch/x86/lib/delay.c:61
Code: 0f 01 f9 66 90 48 c1 e2 20 48 09 c2 49 89 d4 eb 16 f3 90 bf 01 00 00
00 e8 03 c2 01 fa e8 de cd f9 fb 44 39 e8 75 36 0f 01 f9 <66> 90 48 c1 e2
20 48 89 d3 48 09 c3 48 89 d8 4c 29 e0 4c 39 f0 73
RSP: 0018:ffff88808034fc70 EFLAGS: 00000246
RAX: 000000004e0d2263 RBX: 000002d24e0d2178 RCX: 0000000000000000
RDX: 00000000000002d2 RSI: ffffffff8347345c RDI: 0000000000000005
RBP: ffff88808034fc90 R08: ffff8880998302c0 R09: fffffbfff14efd42
R10: fffffbfff14efd41 R11: ffffffff8a77ea0f R12: 000002d24e0d173d
R13: 0000000000000000 R14: 00000000000059d9 R15: ffff88809ccb0108
FS: 0000000000fa4940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 0000000095a99000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__delay arch/x86/lib/delay.c:161 [inline]
__const_udelay+0x59/0x80 arch/x86/lib/delay.c:175
snd_timer_close_locked+0x22a/0xda0 sound/core/timer.c:369
snd_timer_close+0x8a/0x100 sound/core/timer.c:423
snd_timer_user_release+0x98/0x130 sound/core/timer.c:1478
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48
83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48
89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fff58da8ec0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413db1
RDX: 0000000000000000 RSI: 0000000000000081 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000760a88 R09: ffffffffffffffff
R10: 00007fff58da8f90 R11: 0000000000000293 R12: 000000000075bf20
R13: 0000000000000003 R14: 0000000000760a90 R15: 000000000075bf2c


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Takashi Iwai]

This might be the same issue I've been working on.
A test fix patch is below.

Takashi

-- 8< --
From: Takashi Iwai <ti...@suse.de>
Subject: [PATCH] ALSA: timer: Fix incorrectly assigned timer instance

Signed-off-by: Takashi Iwai <ti...@suse.de>
---
sound/core/timer.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 6b724d2ee2de..59ae21b0bb93 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -284,11 +284,11 @@ int snd_timer_open(struct snd_timer_instance **ti,
goto unlock;
}
if (!list_empty(&timer->open_list_head)) {
- timeri = list_entry(timer->open_list_head.next,
+ struct snd_timer_instance *t =
+ list_entry(timer->open_list_head.next,
struct snd_timer_instance, open_list);
- if (timeri->flags & SNDRV_TIMER_IFLG_EXCLUSIVE) {
+ if (t->flags & SNDRV_TIMER_IFLG_EXCLUSIVE) {
err = -EBUSY;
- timeri = NULL;
goto unlock;
}
}
--
2.16.4

[syzbot]

syzbot has bisected this bug to:

commit b2045303147254d01b1db90a83e5df3832c4264b
Author: Clément Péron <peron...@gmail.com>
Date: Mon May 27 20:06:21 2019 +0000

dt-bindings: sound: sun4i-spdif: Add Allwinner H6 compatible

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14acecb4e00000
start commit: a99d8080 Linux 5.4-rc6
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=16acecb4e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=12acecb4e00000

kernel config: https://syzkaller.appspot.com/x/.config?x=8c5e2eca3f31f9bf
dashboard link: https://syzkaller.appspot.com/bug?extid=f1048ebddb93befb085f

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=126bc658e00000

Reported-by: syzbot+f1048e...@syzkaller.appspotmail.com
Fixes: b20453031472 ("dt-bindings: sound: sun4i-spdif: Add Allwinner H6
compatible")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[Mark Brown]

On Wed, Nov 06, 2019 at 04:05:00AM -0800, syzbot wrote:
> syzbot has bisected this bug to:
>
> commit b2045303147254d01b1db90a83e5df3832c4264b
> Author: Clément Péron <peron...@gmail.com>
> Date: Mon May 27 20:06:21 2019 +0000
>
> dt-bindings: sound: sun4i-spdif: Add Allwinner H6 compatible
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14acecb4e00000
> start commit: a99d8080 Linux 5.4-rc6

This bisection is clearly a false positive.

[Takashi Iwai]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git topic/timer-fixes

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer still triggered
crash:
INFO: task hung in snd_timer_close

INFO: task syz-executor.0:12902 blocked for more than 143 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.0 D28160 12902 8828 0x00000004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
snd_timer_user_release+0x98/0x130 sound/core/timer.c:1478
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: c0 c3 0f 1f 80 00 00 00 00 c7 07 00 00 00 00 31 c0 c3 0f 1f 80 00 00
00 00 31 c0 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 b8 <2d> f8 ff ff c3
66 2e 0f 1f 84 00 00 00 00 00 31 c0 c3 66 66 66 66

RSP: 002b:00007ffdc025de30 EFLAGS: 00000293 ORIG_RAX: 0000000000000003

RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413db1

RDX: 0000001b33720000 RSI: 0000000000000000 RDI: 0000000000000003

RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff

R10: 00007ffdc025df10 R11: 0000000000000293 R12: 000000000075c9a0

R13: 000000000075c9a0 R14: 0000000000760a90 R15: 000000000075bf2c

INFO: task syz-executor.3:12905 blocked for more than 143 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.3 D28160 12905 8838 0x00000004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
snd_timer_user_release+0x98/0x130 sound/core/timer.c:1478
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: c0 c3 0f 1f 80 00 00 00 00 c7 07 00 00 00 00 31 c0 c3 0f 1f 80 00 00
00 00 31 c0 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 b8 <2d> f8 ff ff c3
66 2e 0f 1f 84 00 00 00 00 00 31 c0 c3 66 66 66 66

RSP: 002b:00007ffdf8404270 EFLAGS: 00000293 ORIG_RAX: 0000000000000003

RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413db1

RDX: 0000001b2c020000 RSI: 0000000000000000 RDI: 0000000000000003

RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff

R10: 00007ffdf8404350 R11: 0000000000000293 R12: 000000000075c9a0

R13: 000000000075c9a0 R14: 0000000000760a90 R15: 000000000075bf2c

INFO: task syz-executor.1:12908 blocked for more than 144 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.1 D28160 12908 8830 0x00000004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
snd_timer_user_release+0x98/0x130 sound/core/timer.c:1478
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: c0 c3 0f 1f 80 00 00 00 00 c7 07 00 00 00 00 31 c0 c3 0f 1f 80 00 00
00 00 31 c0 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 b8 <2d> f8 ff ff c3
66 2e 0f 1f 84 00 00 00 00 00 31 c0 c3 66 66 66 66

RSP: 002b:00007ffc4ed52170 EFLAGS: 00000293 ORIG_RAX: 0000000000000003

RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413db1

RDX: 0000001b33920000 RSI: 0000000000000000 RDI: 0000000000000003

RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff

R10: 00007ffc4ed52250 R11: 0000000000000293 R12: 000000000075c9a0

R13: 000000000075c9a0 R14: 0000000000760a90 R15: 000000000075bf2c

INFO: task syz-executor.2:12912 blocked for more than 144 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.2 D28160 12912 8837 0x00000004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
snd_timer_user_release+0x98/0x130 sound/core/timer.c:1478
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: c0 c3 0f 1f 80 00 00 00 00 c7 07 00 00 00 00 31 c0 c3 0f 1f 80 00 00
00 00 31 c0 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 b8 <2d> f8 ff ff c3
66 2e 0f 1f 84 00 00 00 00 00 31 c0 c3 66 66 66 66

RSP: 002b:00007ffc11da4be0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003

RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413db1

RDX: 0000001b2bd20000 RSI: 0000000000000000 RDI: 0000000000000003

RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff

R10: 00007ffc11da4cc0 R11: 0000000000000293 R12: 000000000075c9a0

R13: 000000000075c9a0 R14: 0000000000760a90 R15: 000000000075bf2c

INFO: task syz-executor.5:12918 blocked for more than 144 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.5 D28552 12918 8834 0x00000004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118

snd_timer_open+0x98/0x1820 sound/core/timer.c:245

snd_timer_user_tselect sound/core/timer.c:1728 [inline]
__snd_timer_user_ioctl.isra.0+0x68b/0x1fd0 sound/core/timer.c:2003
snd_timer_user_ioctl+0x7a/0xa7 sound/core/timer.c:2033
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.

RSP: 002b:00007fdf5ef32c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010

RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a219
RDX: 0000000020029fcc RSI: 0000000040345410 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf5ef336d4

R13: 00000000004cf428 R14: 00000000004d9760 R15: 00000000ffffffff

INFO: task syz-executor.5:12919 blocked for more than 145 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.5 D29712 12919 8834 0x00000004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.

RSP: 002b:00007fdf5ef11c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010

RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 000000000045a219
RDX: 0000000000000000 RSI: 00000000000054a0 RDI: 0000000000000003
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf5ef126d4

R13: 00000000004c4ae8 R14: 00000000004d9778 R15: 00000000ffffffff

INFO: task syz-executor.5:12920 blocked for more than 145 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.5 D28000 12920 8834 0x00000004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118

snd_timer_open+0x98/0x1820 sound/core/timer.c:245

snd_seq_timer_open+0x240/0x590 sound/core/seq/seq_timer.c:275
queue_use+0xf1/0x270 sound/core/seq/seq_queue.c:489
snd_seq_queue_alloc+0x2c5/0x4d0 sound/core/seq/seq_queue.c:176
snd_seq_ioctl_create_queue+0xb0/0x330 sound/core/seq/seq_clientmgr.c:1548
snd_seq_kernel_client_ctl+0xf8/0x140 sound/core/seq/seq_clientmgr.c:2353
alloc_seq_queue.isra.0+0xdc/0x180 sound/core/seq/oss/seq_oss_init.c:357
snd_seq_oss_open+0x2ff/0x960 sound/core/seq/oss/seq_oss_init.c:215
odev_open+0x70/0x90 sound/core/seq/oss/seq_oss.c:125
soundcore_open+0x453/0x610 sound/sound_core.c:593
chrdev_open+0x245/0x6b0 fs/char_dev.c:414
do_dentry_open+0x4e6/0x1380 fs/open.c:797
vfs_open+0xa0/0xd0 fs/open.c:914
do_last fs/namei.c:3408 [inline]
path_openat+0x10e9/0x46d0 fs/namei.c:3525
do_filp_open+0x1a1/0x280 fs/namei.c:3555
do_sys_open+0x3fe/0x5d0 fs/open.c:1097
__do_sys_openat fs/open.c:1124 [inline]
__se_sys_openat fs/open.c:1118 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1118
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.

RSP: 002b:00007fdf5eef0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101

RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a219
RDX: 0000000000000001 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf5eef16d4

R13: 00000000004c734a R14: 00000000004dcf88 R15: 00000000ffffffff

INFO: task syz-executor.5:12921 blocked for more than 146 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.5 D28552 12921 8834 0x00000004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.

RSP: 002b:00007fdf5eecfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010

RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 000000000045a219
RDX: 0000000000000000 RSI: 00000000000054a0 RDI: 0000000000000003
RBP: 000000000075c118 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf5eed06d4

R13: 00000000004c4ae8 R14: 00000000004d9778 R15: 00000000ffffffff

INFO: task syz-executor.5:12922 blocked for more than 146 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.5 D29520 12922 8834 0x00004004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118

snd_timer_open+0x98/0x1820 sound/core/timer.c:245

snd_timer_user_tselect sound/core/timer.c:1728 [inline]
__snd_timer_user_ioctl.isra.0+0x68b/0x1fd0 sound/core/timer.c:2003
snd_timer_user_ioctl+0x7a/0xa7 sound/core/timer.c:2033
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.

RSP: 002b:00007fdf5eeaec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010

RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a219
RDX: 0000000020029fcc RSI: 0000000040345410 RDI: 0000000000000003
RBP: 000000000075c1c0 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf5eeaf6d4

R13: 00000000004cf428 R14: 00000000004d9760 R15: 00000000ffffffff

INFO: task syz-executor.5:12923 blocked for more than 146 seconds.
Not tainted 5.4.0-rc2+ #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor.5 D28536 12923 8834 0x00000004

Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94f/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118

odev_open+0x5f/0x90 sound/core/seq/oss/seq_oss.c:124
soundcore_open+0x453/0x610 sound/sound_core.c:593
chrdev_open+0x245/0x6b0 fs/char_dev.c:414
do_dentry_open+0x4e6/0x1380 fs/open.c:797
vfs_open+0xa0/0xd0 fs/open.c:914
do_last fs/namei.c:3408 [inline]
path_openat+0x10e9/0x46d0 fs/namei.c:3525
do_filp_open+0x1a1/0x280 fs/namei.c:3555
do_sys_open+0x3fe/0x5d0 fs/open.c:1097
__do_sys_openat fs/open.c:1124 [inline]
__se_sys_openat fs/open.c:1118 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1118
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: Bad RIP value.

RSP: 002b:00007fdf5ee8dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101

RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a219
RDX: 0000000000000001 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 000000000075c268 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf5ee8e6d4

R13: 00000000004c734a R14: 00000000004dcf88 R15: 00000000ffffffff

Showing all locks held in the system:

1 lock held by khungtaskd/1071:
#0: ffffffff88faadc0 (rcu_read_lock){....}, at:
debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5337
1 lock held by rsyslogd/8616:
#0: ffff8880a04a0da0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110
fs/file.c:801
2 locks held by getty/8711:
#0: ffff88809c692f50 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005ee92e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8712:
#0: ffff8880a3956690 (&tty->ldisc_sem){++++}, at:

ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005ef12e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156

2 locks held by getty/8713:
#0: ffff88809c6937d0 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005ee52e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8714:
#0: ffff88808a53ee10 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005ecd2e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8715:
#0: ffff88809c6926d0 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005eed2e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8716:
#0: ffff88808a53e590 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005ed12e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by getty/8717:
#0: ffff88809c674650 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005ec12e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156
2 locks held by syz-executor.4/12901:
2 locks held by syz-executor.0/12902:
#0: ffff8880841a9190 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_release+0x67/0x130 sound/core/timer.c:1476
#1: ffffffff89915420 (register_mutex){+.+.}, at:
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
2 locks held by syz-executor.3/12905:
#0: ffff8880916b3b90 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_release+0x67/0x130 sound/core/timer.c:1476
#1: ffffffff89915420 (register_mutex){+.+.}, at:
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
2 locks held by syz-executor.1/12908:
#0: ffff88809105a1d0 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_release+0x67/0x130 sound/core/timer.c:1476
#1: ffffffff89915420 (register_mutex){+.+.}, at:
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
2 locks held by syz-executor.2/12912:
#0: ffff88808f435190 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_release+0x67/0x130 sound/core/timer.c:1476
#1: ffffffff89915420 (register_mutex){+.+.}, at:
snd_timer_close+0x7e/0x100 sound/core/timer.c:422
2 locks held by syz-executor.5/12918:
#0: ffff888091e7b3d0 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
#1: ffffffff89915420 (register_mutex){+.+.}, at:
snd_timer_open+0x98/0x1820 sound/core/timer.c:245
1 lock held by syz-executor.5/12919:
#0: ffff888091e7b3d0 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
2 locks held by syz-executor.5/12920:
#0: ffffffff89924c40 (register_mutex#4){+.+.}, at: odev_open+0x5f/0x90
sound/core/seq/oss/seq_oss.c:124
#1: ffffffff89915420 (register_mutex){+.+.}, at:
snd_timer_open+0x98/0x1820 sound/core/timer.c:245
1 lock held by syz-executor.5/12921:
#0: ffff88809ab1f410 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
2 locks held by syz-executor.5/12922:
#0: ffff88809ab1f410 (&tu->ioctl_lock){+.+.}, at:
snd_timer_user_ioctl+0x51/0xa7 sound/core/timer.c:2032
#1: ffffffff89915420 (register_mutex){+.+.}, at:
snd_timer_open+0x98/0x1820 sound/core/timer.c:245
1 lock held by syz-executor.5/12923:
#0: ffffffff89924c40 (register_mutex#4){+.+.}, at: odev_open+0x5f/0x90

sound/core/seq/oss/seq_oss.c:124

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

NMI backtrace for cpu 1

CPU: 1 PID: 1071 Comm: khungtaskd Not tainted 5.4.0-rc2+ #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
watchdog+0x9d0/0xef0 kernel/hung_task.c:289
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0

CPU: 0 PID: 12901 Comm: syz-executor.4 Not tainted 5.4.0-rc2+ #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011

RIP: 0010:delay_tsc+0x33/0xc0 arch/x86/lib/delay.c:68
Code: bf 01 00 00 00 41 55 41 54 53 e8 38 a1 02 fa e8 c3 65 fa fb 41 89 c5

0f 01 f9 66 90 48 c1 e2 20 48 09 c2 49 89 d4 eb 16 f3 90 <bf> 01 00 00 00

e8 13 a1 02 fa e8 9e 65 fa fb 44 39 e8 75 36 0f 01
RSP: 0018:ffff88808894fc70 EFLAGS: 00000286
RAX: 0000000080000000 RBX: 00000099d428328a RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff8346edec RDI: 0000000000000001
RBP: ffff88808894fc90 R08: ffff888098cbc6c0 R09: fffffbfff14f0142
R10: fffffbfff14f0141 R11: ffffffff8a780a0f R12: 00000099d427ec22
R13: 0000000000000000 R14: 00000000000059d9 R15: ffff88809d2ebb98
FS: 00000000022eb940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: ffffffffff600400 CR3: 00000000a89e3000 CR4: 00000000001406f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__delay arch/x86/lib/delay.c:161 [inline]
__const_udelay+0x59/0x80 arch/x86/lib/delay.c:175
snd_timer_close_locked+0x22a/0xda0 sound/core/timer.c:369
snd_timer_close+0x8a/0x100 sound/core/timer.c:423
snd_timer_user_release+0x98/0x130 sound/core/timer.c:1478
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48
83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48
89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01

RSP: 002b:00007ffe5313a290 EFLAGS: 00000293 ORIG_RAX: 0000000000000003

RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413db1
RDX: 0000000000000000 RSI: 0000000000000081 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000760a88 R09: ffffffffffffffff

R10: 00007ffe5313a360 R11: 0000000000000293 R12: 000000000075bf20

R13: 0000000000000003 R14: 0000000000760a90 R15: 000000000075bf2c

Tested on:

commit: 1d526faf ALSA: timer: Fix incorrectly assigned timer insta..
git tree:
git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git
topic/timer-fixes
console output: https://syzkaller.appspot.com/x/log.txt?x=14690358e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=5e03978d526c743b

[Eric Biggers]

On Wed, Nov 06, 2019 at 08:53:01AM -0800, syzbot wrote:
> Hello,
>
> syzbot has tested the proposed patch but the reproducer still triggered
> crash:
> INFO: task hung in snd_timer_close

Hi Takashi, has there been any more progress on this bug?

- Eric

[Takashi Iwai]

Not yet, this could be never reproduced locally on my VM, no matter
which config is used.


Takashi

[Eric Biggers]

Since reproducing this failed, and syzbot only hit this 4 months ago and never
since then, I'm just going ahead and invalidating it:

#syz invalid

[Takashi Iwai]

On Sat, 07 Mar 2020 23:40:36 +0100,

Eric Biggers wrote:
>
> On Tue, Nov 19, 2019 at 07:21:18AM +0100, Takashi Iwai wrote:
> > On Tue, 19 Nov 2019 03:28:16 +0100,
> > Eric Biggers wrote:
> > >
> > > On Wed, Nov 06, 2019 at 08:53:01AM -0800, syzbot wrote:
> > > > Hello,
> > > >
> > > > syzbot has tested the proposed patch but the reproducer still triggered
> > > > crash:
> > > > INFO: task hung in snd_timer_close
> > >
> > > Hi Takashi, has there been any more progress on this bug?
> >
> > Not yet, this could be never reproduced locally on my VM, no matter
> > which config is used.
> >
> >
> > Takashi
>
> Since reproducing this failed, and syzbot only hit this 4 months ago and never
> since then, I'm just going ahead and invalidating it:
>
> #syz invalid

Thanks! I believe that it's been fixed meanwhile, too.


Takashi