INFO: task udevd:5194 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd state:D stack:24264 pid:5194 tgid:5194 ppid:1 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5262 [inline]
__schedule+0x1836/0x4ed0 kernel/sched/core.c:6870
__schedule_loop kernel/sched/core.c:6952 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6967
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7024
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
bdev_open+0xe0/0xd30 block/bdev.c:962
blkdev_open+0x457/0x600 block/fops.c:702
do_dentry_open+0x7e4/0x1430 fs/open.c:962
vfs_open+0x3b/0x340 fs/open.c:1094
do_open fs/namei.c:4014 [inline]
path_openat+0x2efb/0x3860 fs/namei.c:4173
do_filp_open+0x1fa/0x410 fs/namei.c:4200
do_sys_openat2+0x121/0x1c0 fs/open.c:1434
do_sys_open fs/open.c:1449 [inline]
__do_sys_openat fs/open.c:1465 [inline]
__se_sys_openat fs/open.c:1460 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1460
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f55b82a7407
RSP: 002b:00007ffe1e98ab70 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f55b895d880 RCX: 00007f55b82a7407
RDX: 00000000000a0800 RSI: 0000560ff0c20130 RDI: ffffffffffffff9c
RBP: 0000560ff0c55ee0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000560fc5be8100 R14: 0000000000000000 R15: 00007ffe1e98ae00
INFO: task syz.1.18:6074 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.18 state:D stack:27624 pid:6074 tgid:6073 ppid:5959 task_flags:0x400140 flags:0x00080003
Call Trace:
context_switch kernel/sched/core.c:5262 [inline]
__schedule+0x1836/0x4ed0 kernel/sched/core.c:6870
__schedule_loop kernel/sched/core.c:6952 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6967
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7024
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
bdev_release+0x1a9/0x650 block/bdev.c:1145
blkdev_release+0x15/0x20 block/fops.c:710
__fput+0x44c/0xa70 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:233
get_signal+0x11ec/0x1340 kernel/signal.c:2807
arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
exit_to_user_mode_loop+0x87/0x4f0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x2e9/0xfa0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4a8818f6c9
RSP: 002b:00007f4a890fd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 00007f4a883e5fa0 RCX: 00007f4a8818f6c9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00007f4a88211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4a883e6038 R14: 00007f4a883e5fa0 R15: 00007ffca834c5e8
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e33d560 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e33d560 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8e33d560 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/1:1/43:
5 locks held by kworker/u8:6/1157:
1 lock held by udevd/5194:
#0: ffff8880257c6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:962
2 locks held by getty/5584:
#0: ffff88814e24d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900036c32f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
1 lock held by udevd/5907:
#0: ffff8880257c6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:962
2 locks held by kworker/u9:2/5917:
#0: ffff888025eb5148 ((wq_completion)nbd4-recv){+.+.}-{0:0}, at: process_one_work+0x841/0x15e0 kernel/workqueue.c:3236
#1: ffffc90004a4fb80 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x868/0x15e0 kernel/workqueue.c:3237
2 locks held by kworker/u9:5/5965:
#0: ffff888025eaf948 ((wq_completion)nbd3-recv){+.+.}-{0:0}, at: process_one_work+0x841/0x15e0 kernel/workqueue.c:3236
#1: ffffc9000414fb80 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x868/0x15e0 kernel/workqueue.c:3237
2 locks held by kworker/u9:6/5968:
#0: ffff888025ea8948 ((wq_completion)nbd2-recv){+.+.}-{0:0}, at: process_one_work+0x841/0x15e0 kernel/workqueue.c:3236
#1: ffffc90003c8fb80 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x868/0x15e0 kernel/workqueue.c:3237
2 locks held by kworker/u9:8/5970:
#0: ffff888025e89948 ((wq_completion)nbd0-recv){+.+.}-{0:0}, at: process_one_work+0x841/0x15e0 kernel/workqueue.c:3236
#1: ffffc9000407fb80 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x868/0x15e0 kernel/workqueue.c:3237
1 lock held by syz.1.18/6074:
#0: ffff8880257c6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1a9/0x650 block/bdev.c:1145
4 locks held by syz.3.694/7488:
#0: ffff888025eab278 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_start_device+0x189/0xb10 drivers/block/nbd.c:1490
#1: ffff888025de4bb8 (&q->limits_lock){+.+.}-{4:4}, at: queue_limits_start_update include/linux/blkdev.h:1088 [inline]
#1: ffff888025de4bb8 (&q->limits_lock){+.+.}-{4:4}, at: nbd_set_size+0x292/0x6a0 drivers/block/nbd.c:354
#2: ffff888025de4558 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
#2: ffff888025de4558 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: queue_limits_commit_update_frozen+0x56/0xd0 block/blk-settings.c:599
#3: ffff888025de4590 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
#3: ffff888025de4590 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: queue_limits_commit_update_frozen+0x56/0xd0 block/blk-settings.c:599
4 locks held by syz.2.695/7490:
#0: ffff888025e8c278 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_start_device+0x189/0xb10 drivers/block/nbd.c:1490
#1: ffff888025de41e8 (&q->limits_lock){+.+.}-{4:4}, at: queue_limits_start_update include/linux/blkdev.h:1088 [inline]
#1: ffff888025de41e8 (&q->limits_lock){+.+.}-{4:4}, at: nbd_set_size+0x292/0x6a0 drivers/block/nbd.c:354
#2: ffff888025de3b88 (&q->q_usage_counter(io)#51){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
#2: ffff888025de3b88 (&q->q_usage_counter(io)#51){++++}-{0:0}, at: queue_limits_commit_update_frozen+0x56/0xd0 block/blk-settings.c:599
#3: ffff888025de3bc0 (&q->q_usage_counter(queue)#35){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
#3: ffff888025de3bc0 (&q->q_usage_counter(queue)#35){+.+.}-{0:0}, at: queue_limits_commit_update_frozen+0x56/0xd0 block/blk-settings.c:599
4 locks held by syz.4.696/7498:
#0: ffff888025eb0a78 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_start_device+0x189/0xb10 drivers/block/nbd.c:1490
#1: ffff888025de5588 (&q->limits_lock){+.+.}-{4:4}, at: queue_limits_start_update include/linux/blkdev.h:1088 [inline]
#1: ffff888025de5588 (&q->limits_lock){+.+.}-{4:4}, at: nbd_set_size+0x292/0x6a0 drivers/block/nbd.c:354
#2: ffff888025de4f28 (&q->q_usage_counter(io)#53){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
#2: ffff888025de4f28 (&q->q_usage_counter(io)#53){++++}-{0:0}, at: queue_limits_commit_update_frozen+0x56/0xd0 block/blk-settings.c:599
#3: ffff888025de4f60 (&q->q_usage_counter(queue)#37){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
#3: ffff888025de4f60 (&q->q_usage_counter(queue)#37){+.+.}-{0:0}, at: queue_limits_commit_update_frozen+0x56/0xd0 block/blk-settings.c:599
4 locks held by syz.0.697/7497:
#0: ffff888025e85278 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_start_device+0x189/0xb10 drivers/block/nbd.c:1490
#1: ffff888025de3818 (&q->limits_lock){+.+.}-{4:4}, at: queue_limits_start_update include/linux/blkdev.h:1088 [inline]
#1: ffff888025de3818 (&q->limits_lock){+.+.}-{4:4}, at: nbd_set_size+0x292/0x6a0 drivers/block/nbd.c:354
#2: ffff888025de31b8 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
#2: ffff888025de31b8 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: queue_limits_commit_update_frozen+0x56/0xd0 block/blk-settings.c:599
#3: ffff888025de31f0 (&q->q_usage_counter(queue)#33){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
#3: ffff888025de31f0 (&q->q_usage_counter(queue)#33){+.+.}-{0:0}, at: queue_limits_commit_update_frozen+0x56/0xd0 block/blk-settings.c:599
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
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]
check_hung_uninterruptible_tasks kernel/hung_task.c:336 [inline]
watchdog+0xfa8/0xff0 kernel/hung_task.c:499
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:245
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7498 Comm: syz.4.696 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:io_serial_out+0x7c/0xc0 drivers/tty/serial/8250/8250_port.c:407
Code: 27 9d fc 44 89 f9 d3 e5 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 7c 80 03 fd 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d e9 97 15 42 06 cc 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc9000cb87410 EFLAGS: 00000002
RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: ffff888140b90237 R09: 1ffff11028172046
R10: dffffc0000000000 R11: ffffffff8524b880 R12: dffffc0000000000
R13: ffffffff99c9c942 R14: ffffffff99fb0420 R15: 0000000000000000
FS: 00007f2ac9d6f6c0(0000) GS:ffff888125a78000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2ac9d6fd58 CR3: 0000000030a32000 CR4: 00000000003526f0
Call Trace:
serial_port_out include/linux/serial_core.h:811 [inline]
serial8250_console_putchar drivers/tty/serial/8250/8250_port.c:3192 [inline]
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:-1 [inline]
serial8250_console_write+0x1410/0x1ba0 drivers/tty/serial/8250/8250_port.c:3342
console_emit_next_record kernel/printk/printk.c:3108 [inline]
console_flush_one_record kernel/printk/printk.c:3194 [inline]
console_flush_all+0x745/0xb60 kernel/printk/printk.c:3268
__console_flush_and_unlock kernel/printk/printk.c:3298 [inline]
console_unlock+0xbb/0x190 kernel/printk/printk.c:3338
vprintk_emit+0x4c5/0x590 kernel/printk/printk.c:2423
_printk+0xcf/0x120 kernel/printk/printk.c:2448
set_capacity_and_notify+0x208/0x2d0 block/genhd.c:93
nbd_set_size+0x512/0x6a0 drivers/block/nbd.c:380
nbd_start_device_ioctl drivers/block/nbd.c:1548 [inline]
__nbd_ioctl drivers/block/nbd.c:1623 [inline]
nbd_ioctl+0x56e/0xe10 drivers/block/nbd.c:1663
blkdev_ioctl+0x60e/0x710 block/ioctl.c:707
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2ac8f8f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2ac9d6f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f2ac91e6180 RCX: 00007f2ac8f8f6c9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00007f2ac9011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2ac91e6218 R14: 00007f2ac91e6180 R15: 00007ffd3d8758e8