INFO: task udevd:14708 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:24576 pid:14708 ppid:3637 flags:0x00004002
Call Trace:
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
schedule+0xb9/0x180 kernel/sched/core.c:6637
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6696
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x555/0xaf0 kernel/locking/mutex.c:747
device_lock include/linux/device.h:840 [inline]
uevent_show+0x16c/0x320 drivers/base/core.c:2669
dev_attr_show+0x50/0xb0 drivers/base/core.c:2372
sysfs_kf_seq_show+0x349/0x4b0 fs/sysfs/file.c:59
seq_read_iter+0x49b/0xd50 fs/seq_file.c:230
call_read_iter include/linux/fs.h:2259 [inline]
new_sync_read fs/read_write.c:389 [inline]
vfs_read+0x434/0x920 fs/read_write.c:470
ksys_read+0x143/0x240 fs/read_write.c:613
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdf2faa7407
RSP: 002b:00007ffd480b6b40 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fdf30189880 RCX: 00007fdf2faa7407
RDX: 0000000000001000 RSI: 000055e334d9aa50 RDI: 0000000000000008
RBP: 00007fdf2fbefff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000a
R13: 00007fdf2fbefea0 R14: 0000000000000000 R15: 000055e334d847a0
Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8cb2b630 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8cb2be50 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
3 locks held by kworker/1:0/22:
#0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc900001c7d00 ((work_completion)(&pwq->unbound_release_work)
){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffffffff8cb30978 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
#2: ffffffff8cb30978 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x346/0x830 kernel/rcu/tree_exp.h:962
1 lock held by khungtaskd/27:
#0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
2 locks held by kworker/1:2/126:
#0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc90002db7d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
2 locks held by getty/4027:
#0: ffff88814d4d4098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
9 locks held by kworker/1:10/4983:
2 locks held by syz-executor/8475:
#0: ffff888060a400e0 (&type->s_umount_key#51){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
#1: ffffffff8cb30978 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
#1: ffffffff8cb30978 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x346/0x830 kernel/rcu/tree_exp.h:962
4 locks held by udevd/14708:
#0: ffff88807be55c30 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xad/0xd50 fs/seq_file.c:182
#1: ffff888054e91888 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x58/0x410 fs/kernfs/file.c:172
#2: ffff888057243660 (kn->active#5){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
#2: ffff888057243660 (kn->active#5){++++}-{0:0}, at: kernfs_seq_start+0xae/0x410 fs/kernfs/file.c:173
#3: ffff888057016190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:840 [inline]
#3: ffff888057016190 (&dev->mutex){....}-{3:3}, at: uevent_show+0x16c/0x320 drivers/base/core.c:2669
4 locks held by syz.9.2086/18120:
=============================================
NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
watchdog+0xeee/0xf30 kernel/hung_task.c:377
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5084 Comm: kworker/u4:17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:check_preemption_disabled+0x1/0x110 lib/smp_processor_id.c:13
Code: e0 74 bc 8c 4c 89 f6 e8 9d d1 16 fa e9 6e ff ff ff 00 00 cc cc 00 00 cc cc 48 c7 c7 00 f7 de 8a 48 c7 c6 40 f7 de 8a eb 00 55 <41> 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24
RSP: 0018:ffffc90004b97a30 EFLAGS: 00000046
RAX: 1ffff1100f457c82 RBX: 5f1e42c469f329e1 RCX: 0000000000000001
RDX: 0000000000000002 RSI: ffffffff8a8c1700 RDI: ffffffff8adef760
RBP: ffffc90004b97b60 R08: dffffc0000000000 R09: fffffbfff1c3ed56
R10: fffffbfff1c3ed56 R11: 1ffffffff1c3ed55 R12: ffff88807a2be470
R13: dffffc0000000000 R14: ffff88807a2be410 R15: 1ffff92000972f54
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f22f39b7198 CR3: 000000000c88e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline]
lock_release+0x54f/0x910 kernel/locking/lockdep.c:5684
rcu_lock_release include/linux/rcupdate.h:355 [inline]
rcu_read_unlock include/linux/rcupdate.h:824 [inline]
batadv_nc_process_nc_paths+0x2f7/0x390 net/batman-adv/network-coding.c:699
batadv_nc_worker+0x527/0x600 net/batman-adv/network-coding.c:735
process_one_work+0x898/0x1160 kernel/workqueue.c:2292
worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295