syzbot
INFO: task hung in io_wq_put_and_exit
Status:
upstream: reported C repro on 2025/06/25 22:50
Bug presence:
origin:lts-only
[Documentation on labels]
Reported-by: syzbot+ea8018030af6aec75b1e@syzkaller.appspotmail.com
First crash: 417d, last: 2d19h
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Bug presence (2)
| Date |
Name |
Commit |
Repro |
Result |
| 2025/12/31 |
linux-6.6.y (ToT) |
5fa4793a2d2d |
C
|
[report] INFO: task hung in io_wq_put_and_exit
|
| 2025/12/31 |
upstream (ToT) |
dbf8fe85a16a |
C
|
Didn't crash |
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Last patch testing requests (2)
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▼
Fix bisection attempts (1)
| Created |
Duration |
User |
Patch |
Repo |
Result |
| 2025/08/07 00:08 |
9h48m
|
fix candidate
|
|
upstream |
OK
(1)
job log
|
Sample crash report:
INFO: task syz.0.20:5939 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.20 state:D stack:25512 pid:5939 ppid:5893 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
schedule+0xbd/0x170 kernel/sched/core.c:6775
schedule_timeout+0xc1/0x2d0 kernel/time/timer.c:2144
do_wait_for_common kernel/sched/completion.c:95 [inline]
__wait_for_common kernel/sched/completion.c:116 [inline]
wait_for_common kernel/sched/completion.c:127 [inline]
wait_for_completion+0x2c6/0x5a0 kernel/sched/completion.c:148
io_wq_exit_workers io_uring/io-wq.c:1267 [inline]
io_wq_put_and_exit+0x493/0x820 io_uring/io-wq.c:1295
io_uring_clean_tctx+0x12f/0x1b0 io_uring/tctx.c:204
io_uring_cancel_generic+0x610/0x6c0 io_uring/io_uring.c:3507
io_uring_files_cancel include/linux/io_uring.h:69 [inline]
do_exit+0x5f4/0x2530 kernel/exit.c:836
do_group_exit+0x22d/0x2f0 kernel/exit.c:1032
__do_sys_exit_group kernel/exit.c:1043 [inline]
__se_sys_exit_group kernel/exit.c:1041 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1041
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb4dd99e0d9
RSP: 002b:00007ffc7e42dc08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb4dd99e0d9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffc7e42dc6c R08: 0000000000000000 R09: 00000000000927c0
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000003
R13: 00000000000927c0 R14: 0000000000018a21 R15: 00007ffc7e42dcc0
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/29:
#0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by kworker/u4:9/1102:
2 locks held by getty/5534:
#0: ffff88814d2ac0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x428/0x1370 drivers/tty/n_tty.c:2217
2 locks held by dhcpcd/6134:
#0: ffff88805afbc130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline]
#0: ffff88805afbc130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x33/0xd40 net/packet/af_packet.c:3264
#1: ffffffff8d137778 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline]
#1: ffffffff8d137778 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x306/0x880 kernel/rcu/tree_exp.h:1004
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
watchdog+0xf59/0xfa0 kernel/hung_task.c:379
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 1145 Comm: kworker/u4:11 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:check_region_inline mm/kasan/generic.c:-1 [inline]
RIP: 0010:kasan_check_range+0x12/0x290 mm/kasan/generic.c:187
Code: 0f 0b b8 ea ff ff ff c3 0f 0b b8 ea ff ff ff c3 cc cc cc cc cc cc cc cc 66 0f 1f 00 b0 01 48 85 f6 0f 84 b4 01 00 00 55 41 57 <41> 56 41 55 41 54 53 4c 8d 04 37 49 39 f8 0f 82 13 02 00 00 49 89
RSP: 0018:ffffc900048df4c8 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000003 RCX: ffffffff816893c2
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff911ed5e8
RBP: ffffc900048df728 R08: dffffc0000000000 R09: 1ffffffff223dac1
R10: dffffc0000000000 R11: fffffbfff223dac2 R12: 0000000000000003
R13: ffff888023da0b80 R14: 000000000000077a R15: ffff888023da0b80
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e63eb79660 CR3: 000000002f542000 CR4: 00000000003506f0
Call Trace:
<TASK>
instrument_atomic_read include/linux/instrumented.h:68 [inline]
_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
hlock_class kernel/locking/lockdep.c:228 [inline]
check_wait_context kernel/locking/lockdep.c:4798 [inline]
__lock_acquire+0x952/0x7d80 kernel/locking/lockdep.c:5087
lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
__debug_check_no_obj_freed lib/debugobjects.c:1034 [inline]
debug_check_no_obj_freed+0x9e/0x520 lib/debugobjects.c:1075
slab_free_hook mm/slub.c:1786 [inline]
slab_free_freelist_hook+0xd2/0x1a0 mm/slub.c:1837
slab_free mm/slub.c:3830 [inline]
__kmem_cache_free+0xba/0x1f0 mm/slub.c:3843
skb_kfree_head net/core/skbuff.c:946 [inline]
skb_free_head net/core/skbuff.c:958 [inline]
skb_release_data+0x609/0x7f0 net/core/skbuff.c:988
skb_release_all net/core/skbuff.c:1054 [inline]
__kfree_skb net/core/skbuff.c:1068 [inline]
consume_skb+0xb2/0x110 net/core/skbuff.c:1284
nsim_dev_trap_report drivers/net/netdevsim/dev.c:821 [inline]
nsim_dev_trap_report_work+0x723/0xa90 drivers/net/netdevsim/dev.c:851
process_one_work kernel/workqueue.c:2657 [inline]
process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
* Struck through repros no longer work on HEAD.