syzbot
INFO: task hung in trace_set_clr_event
Status:
upstream: reported on 2026/09/09 11:05
Reported-by: syzbot+f23e5fb3e1734d860759@syzkaller.appspotmail.com
First crash: 65d, last: 11d
Sample crash report:
INFO: task syz.6.582:7091 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.582 state:D stack:24976 pid: 7091 ppid: 5230 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11c3/0x4350 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
__mutex_lock_common+0xdf5/0x2400 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
__ftrace_set_clr_event kernel/trace/trace_events.c:1195 [inline]
trace_set_clr_event+0xbe/0x130 kernel/trace/trace_events.c:1261
bpf_get_trace_printk_proto+0x1e/0x80 kernel/trace/bpf_trace.c:408
check_helper_call+0x1df/0x5750 kernel/bpf/verifier.c:6554
do_check+0x62de/0xf170 kernel/bpf/verifier.c:11463
do_check_common+0xe7f/0x16e0 kernel/bpf/verifier.c:13542
do_check_main kernel/bpf/verifier.c:13605 [inline]
bpf_check+0x32e9/0xf5f0 kernel/bpf/verifier.c:14188
bpf_prog_load+0xfdf/0x14e0 kernel/bpf/syscall.c:2354
__sys_bpf+0x532/0x6f0 kernel/bpf/syscall.c:4657
__do_sys_bpf kernel/bpf/syscall.c:4761 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4759 [inline]
__x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f3fe2c4a559
RSP: 002b:00007f3fe0ea1028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f3fe2ed0fa0 RCX: 00007f3fe2c4a559
RDX: 0000000000000094 RSI: 0000200000000800 RDI: 0000000000000005
RBP: 00007f3fe2ce1b50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3fe2ed1038 R14: 00007f3fe2ed0fa0 R15: 00007ffc197a35d8
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8d11efa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:2/155:
1 lock held by dhcpcd/3855:
#0: ffffffff8e26ca48 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
#0: ffffffff8e26ca48 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
2 locks held by getty/3945:
#0: ffff88807f071098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
2 locks held by kworker/0:5/4279:
#0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc9000313fd00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
2 locks held by kworker/0:6/4280:
#0: ffff888017872138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc9000314fd00 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
3 locks held by kworker/0:9/4339:
#0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc9000321fd00 (key_gc_work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
#2: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
#2: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845
4 locks held by kworker/u4:12/4526:
#0: ffff888017879138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc900032dfd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
#2: ffffffff8e26ca48 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:251
#3: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
#3: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845
6 locks held by syz.4.108/4702:
1 lock held by syz.6.582/7091:
#0: ffffffff8d16c808 (event_mutex){+.+.}-{3:3}, at: __ftrace_set_clr_event kernel/trace/trace_events.c:1195 [inline]
#0: ffffffff8d16c808 (event_mutex){+.+.}-{3:3}, at: trace_set_clr_event+0xbe/0x130 kernel/trace/trace_events.c:1261
2 locks held by syz.3.777/8100:
#0: ffff888021431918 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf1/0x780 block/bdev.c:911
#1: ffff888021633468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xb50 drivers/block/loop.c:1366
1 lock held by syz-executor/8216:
#0: ffffffff8e26ca48 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
#0: ffffffff8e26ca48 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
=============================================
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 10/07/2026
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
watchdog+0xe1b/0xe60 kernel/hung_task.c:369
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4370 Comm: kworker/u4:8 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
RIP: 0010:__lock_acquire+0x5dd/0x7d40 kernel/locking/lockdep.c:5062
Code: c0 44 09 f8 8b 4c 24 18 83 e1 03 c1 e1 10 09 c1 8b 84 24 c0 00 00 00 83 e0 01 c1 e0 12 09 c8 41 c1 e5 14 41 09 c5 8b 44 24 50 <c1> e0 13 41 c1 e6 15 41 09 c6 41 09 de 45 09 ee 48 8b 44 24 48 42
RSP: 0018:ffffc900032cf680 EFLAGS: 00000006
RAX: 0000000000000000 RBX: 0000000000000015 RCX: 0000000000020000
RDX: 0000000000000015 RSI: 0000000000000000 RDI: ffff88807dc7c6f0
RBP: ffffc900032cf8c8 R08: dffffc0000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1cda646 R12: ffff88807dc7c654
R13: 0000000000020000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0da9c3c2f8 CR3: 000000002bc90000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
rcu_read_lock include/linux/rcupdate.h:740 [inline]
batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:769 [inline]
batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:849 [inline]
batadv_iv_ogm_schedule+0x434/0x1000 net/batman-adv/bat_iv_ogm.c:908
batadv_iv_send_outstanding_bat_ogm_packet+0x6e9/0x800 net/batman-adv/bat_iv_ogm.c:1805
process_one_work+0x867/0xff0 kernel/workqueue.c:2310
worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
* Struck through repros no longer work on HEAD.