INFO: task syz.0.4568:23762 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.0.4568 state:D stack:26712 pid:23762 tgid:23761 ppid:21851 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5258 [inline]
__schedule+0x150e/0x5070 kernel/sched/core.c:6866
__schedule_loop kernel/sched/core.c:6948 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6963
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7020
__mutex_lock_common kernel/locking/mutex.c:692 [inline]
__mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:776
sync_bdevs+0x27e/0x470 block/bdev.c:1305
ksys_sync+0xb9/0x150 fs/sync.c:105
__ia32_sys_sync+0xe/0x20 fs/sync.c:113
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc6e938f749
RSP: 002b:00007fc6ea1f9038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fc6e95e5fa0 RCX: 00007fc6e938f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fc6e95e5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc6e95e6038 R14: 00007fc6e95e5fa0 R15: 00007ffda49885c8
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e33f2e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e33f2e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8e33f2e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
1 lock held by udevd/5842:
#0: ffff888024e95358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:962
2 locks held by syz.9.3995/21632:
#0: ffffffff8f794230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1:
ffffffff8e635308 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1660 fs/nfsd/nfsctl.c:1880
2 locks held by getty/22623:
#0: ffff88803464d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900038c52f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x449/0x1460 drivers/tty/n_tty.c:2211
1 lock held by syz.0.4568/23762:
#0: ffff888024e95358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470 block/bdev.c:1305
2 locks held by syz.2.4729/24276:
#0: ffff888029ec00e0 (&type->s_umount_key#108){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff888029ec00e0 (&type->s_umount_key#108){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff888029ec00e0 (&type->s_umount_key#108){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:506
#1: ffffffff8e635308 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:575
2 locks held by syz.6.4985/26022:
#0: ffffffff8f794230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8e635308 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1660 fs/nfsd/nfsctl.c:1880
=============================================
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 10/25/2025
Call Trace:
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:363 [inline]
watchdog+0xe40/0xe90 kernel/hung_task.c:557
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 24777 Comm: kworker/1:4 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events legacy_dvb_usb_read_remote_control
RIP: 0010:number+0x11b/0xf60 lib/vsprintf.c:485
Code: e6 02 44 89 64 24 3c 41 0f 44 dc 31 ff e8 3d b7 5e f6 89 de 83 e6 01 31 ff e8 31 b7 5e f6 89 5c 24 14 f6 c3 01 4c 89 7c 24 58 <75> 1b e8 de b2 5e f6 b0 01 89 44 24 38 c7 44 24 34 00 00 00 00 4d
RSP: 0018:ffffc90004706e80 EFLAGS: 00000246
RAX: ffffffff8b63456f RBX: 00000000ffff0a10 RCX: 0000000000000000
RDX: ffff88807585db80 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90004706fa0 R08: ffff88807585db80 R09: 0000000000000008
R10: 0000000000000007 R11: 0000000000000000 R12: 00000000ffff0a10
R13: 000000000009155b R14: ffffc90004707287 R15: 1ffff920008e0ddc
FS: 0000000000000000(0000) GS:ffff888125adc000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5fab111000 CR3: 0000000075938000 CR4: 00000000003526f0
Call Trace:
vsnprintf+0x8e5/0xee0 lib/vsprintf.c:2912
sprintf+0xd9/0x120 lib/vsprintf.c:3111
print_time kernel/printk/printk.c:1357 [inline]
info_print_prefix+0x155/0x310 kernel/printk/printk.c:1383
record_print_text+0x154/0x420 kernel/printk/printk.c:1432
printk_get_next_message+0x26d/0x7b0 kernel/printk/printk.c:3018
console_emit_next_record kernel/printk/printk.c:3083 [inline]
console_flush_one_record kernel/printk/printk.c:3215 [inline]
console_flush_all+0x514/0xb60 kernel/printk/printk.c:3289
__console_flush_and_unlock kernel/printk/printk.c:3319 [inline]
console_unlock+0xbb/0x190 kernel/printk/printk.c:3359
vprintk_emit+0x4f8/0x5f0 kernel/printk/printk.c:2426
_printk+0xcf/0x120 kernel/printk/printk.c:2451
m920x_read drivers/media/usb/dvb-usb/m920x.c:40 [inline]
m920x_rc_query+0x2f6/0x830 drivers/media/usb/dvb-usb/m920x.c:-1
legacy_dvb_usb_read_remote_control+0x100/0x470 drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
process_one_work+0x93a/0x15a0 kernel/workqueue.c:3279
process_scheduled_works kernel/workqueue.c:3362 [inline]
worker_thread+0x9b0/0xee0 kernel/workqueue.c:3443
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246