INFO: task syz.4.839:9016 blocked for more than 143 seconds.
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.839 state:D stack:26792 pid:9016 tgid:9015 ppid:5812 task_flags:0x400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0xfee/0x60e0 kernel/sched/core.c:6907
__schedule_loop kernel/sched/core.c:6989 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:7004
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7061
__mutex_lock_common kernel/locking/mutex.c:692 [inline]
__mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776
sync_bdevs+0x153/0x480 block/bdev.c:1304
ksys_sync+0xb0/0xf0 fs/sync.c:105
__do_sys_sync+0xe/0x20 fs/sync.c:111
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc03d79bf79
RSP: 002b:00007fc03e602028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fc03da15fa0 RCX: 00007fc03d79bf79
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fc03da15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc03da16038 R14: 00007fc03da15fa0 R15: 00007ffe03e2f028
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e7e94a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#0: ffffffff8e7e94a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#0: ffffffff8e7e94a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
8 locks held by kworker/1:2/977:
2 locks held by kworker/1:1H/2737:
2 locks held by getty/5566:
#0: ffff888033a260a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
4 locks held by udevd/5798:
#0: ffff88805e455c30 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x1270 fs/seq_file.c:183
#1: ffff88805d62dc88 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:172
#2: ffff888068a68d28 (kn->active#13){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
#2: ffff888068a68d28 (kn->active#13){++++}-{0:0}, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:173
#3: ffff88805f14c198 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:900 [inline]
#3: ffff88805f14c198 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
3 locks held by kworker/1:5/5888:
2 locks held by kworker/u8:11/6714:
#0: ffff88801ef77148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x1287/0x1920 kernel/workqueue.c:3250
#1: ffffc900051ffd08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x93c/0x1920 kernel/workqueue.c:3251
1 lock held by udevd/7025:
#0: ffff8880275a0358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:961
1 lock held by syz.4.839/9016:
#0: ffff8880275a0358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x153/0x480 block/bdev.c:1304
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x141/0x190 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
watchdog+0xd25/0x1050 kernel/hung_task.c:515
kthread+0x370/0x450 kernel/kthread.c:467
ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 977 Comm: kworker/1:2 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: usb_hub_wq hub_event
RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:59 [inline]
RIP: 0010:__unwind_start+0x411/0x7f0 arch/x86/kernel/unwind_orc.c:771
Code: 00 41 8b 06 85 c0 0f 84 e5 fe ff ff 41 80 7d 00 00 0f 85 9e 02 00 00 41 80 3c 24 00 49 8b 46 08 0f 85 76 02 00 00 49 8b 56 10 <48> 39 c3 72 b3 48 39 d3 73 ae 48 8d 4b 08 48 39 ca 72 a5 48 39 c8
RSP: 0018:ffffc9000463e6a0 EFLAGS: 00000246
RAX: ffffc90004638000 RBX: ffffc9000463e780 RCX: ffffc9000463e5f4
RDX: ffffc90004640000 RSI: ffffffff8de457a5 RDI: ffff888027e7a904
RBP: dffffc0000000000 R08: 0000000000000001 R09: 0000000000000007
R10: 0000000000000200 R11: 000000000000aefb R12: fffff520008c7ce0
R13: fffff520008c7cdf R14: ffffc9000463e6f0 R15: ffffc9000463e6f8
FS: 0000000000000000(0000) GS:ffff888124458000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9b83e4cf88 CR3: 0000000069085000 CR4: 00000000003526f0
Call Trace:
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0x73/0xf0 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2670 [inline]
slab_free mm/slub.c:6082 [inline]
kfree+0x1f6/0x6b0 mm/slub.c:6399
__free_kfree include/linux/slab.h:517 [inline]
snd_mixer_oss_build_test+0x13d/0x3d0 sound/core/oss/mixer_oss.c:895
snd_mixer_oss_build_test_all+0x2b4/0x6e0 sound/core/oss/mixer_oss.c:961
snd_mixer_oss_build_input+0x139/0xd90 sound/core/oss/mixer_oss.c:1020
snd_mixer_oss_build sound/core/oss/mixer_oss.c:1279 [inline]
snd_mixer_oss_notify_handler+0x48d/0x990 sound/core/oss/mixer_oss.c:1347
snd_card_register+0x2e1/0x7c0 sound/core/init.c:923
try_to_register_card+0x1d6/0x3a0 sound/usb/card.c:902
usb_audio_probe+0xf91/0x3a90 sound/usb/card.c:1071
usb_probe_interface+0x303/0x8f0 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:583 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:661
__driver_probe_device+0x1de/0x400 drivers/base/dd.c:803
driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:833
__device_attach_driver+0x1ff/0x3e0 drivers/base/dd.c:961
bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
__device_attach+0x1e4/0x4d0 drivers/base/dd.c:1033
device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1088
bus_probe_device+0x64/0x160 drivers/base/bus.c:574
device_add+0x11d9/0x1950 drivers/base/core.c:3689
usb_set_configuration+0xd97/0x1c60 drivers/usb/core/message.c:2210
usb_generic_driver_probe+0xa1/0xe0 drivers/usb/core/generic.c:250
usb_probe_device+0xef/0x400 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:583 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:661
__driver_probe_device+0x1de/0x400 drivers/base/dd.c:803
driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:833
__device_attach_driver+0x1ff/0x3e0 drivers/base/dd.c:961
bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
__device_attach+0x1e4/0x4d0 drivers/base/dd.c:1033
device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1088
bus_probe_device+0x64/0x160 drivers/base/bus.c:574
device_add+0x11d9/0x1950 drivers/base/core.c:3689
usb_new_device.cold+0x685/0x115c drivers/usb/core/hub.c:2695
hub_port_connect drivers/usb/core/hub.c:5567 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
port_event drivers/usb/core/hub.c:5871 [inline]
hub_event+0x314d/0x4af0 drivers/usb/core/hub.c:5953
process_one_work+0x9d7/0x1920 kernel/workqueue.c:3275
process_scheduled_works kernel/workqueue.c:3358 [inline]
worker_thread+0x5da/0xe40 kernel/workqueue.c:3439
kthread+0x370/0x450 kernel/kthread.c:467
ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245