syzbot


INFO: task hung in io_uring_del_tctx_node (2)

Status: upstream: reported on 2025/07/24 10:20
Reported-by: syzbot+915c6107499bce8b0de3@syzkaller.appspotmail.com
First crash: 148d, last: 34d
Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in io_uring_del_tctx_node 1 2 968d 972d 0/3 auto-obsoleted due to no activity on 2023/08/23 09:02
upstream INFO: task hung in io_uring_del_tctx_node (3) io-uring 1 1 533d 533d 0/29 auto-obsoleted due to no activity on 2024/10/02 07:14
upstream INFO: task hung in io_uring_del_tctx_node (4) io-uring 1 C done 8 204d 200d 0/29 closed as invalid on 2025/06/02 13:41
upstream INFO: task hung in io_uring_del_tctx_node io-uring fs 1 C unreliable 37 1384d 1547d 20/29 fixed on 2022/03/08 16:11
upstream INFO: task hung in io_uring_del_tctx_node (5) io-uring 1 C done 18 22d 53d 27/29 upstream: reported C repro on 2025/10/27 21:07
upstream INFO: task hung in io_uring_del_tctx_node (2) io-uring 1 C error error 20 1013d 1375d 0/29 auto-obsoleted due to no activity on 2023/07/30 22:24

Sample crash report:
INFO: task syz.3.75:4522 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.75        state:D stack:27712 pid: 4522 ppid:  4183 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 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+0xc71/0x2390 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 io_uring_del_tctx_node+0xe8/0x2c0 io_uring/io_uring.c:9825
 io_uring_clean_tctx io_uring/io_uring.c:9841 [inline]
 io_uring_cancel_generic+0x5ec/0x860 io_uring/io_uring.c:9921
 io_uring_files_cancel include/linux/io_uring.h:16 [inline]
 do_exit+0x24a/0x20a0 kernel/exit.c:829
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 get_signal+0x6ca/0x12c0 kernel/signal.c:2900
 arch_do_signal_or_restart+0xc1/0x1300 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f234bc576c9
RSP: 002b:00007f2349e9d0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f234beae098 RCX: 00007f234bc576c9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f234beae098
RBP: 00007f234beae090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f234beae128 R14: 00007ffd3cca6320 R15: 00007ffd3cca6408
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3943:
 #0: ffff88802c0a4098 (&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+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
4 locks held by udevd/4436:
 #0: ffff88802a4c09e0 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xad/0xd50 fs/seq_file.c:182
 #1: ffff88808145b488 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x51/0x3c0 fs/kernfs/file.c:112
 #2: ffff888031318008
 (kn->active#32){++++}-{0:0}, at: kernfs_seq_start+0x71/0x3c0 fs/kernfs/file.c:113
 #3: ffff88807c1231a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #3: ffff88807c1231a8 (&dev->mutex){....}-{3:3}, at: uevent_show+0x17a/0x330 drivers/base/core.c:2408
2 locks held by syz.3.75/4521:
1 lock held by syz.3.75/4522:
 #0: ffff888028d5c0a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_uring_del_tctx_node+0xe8/0x2c0 io_uring/io_uring.c:9825
6 locks held by kworker/0:18/5158:
2 locks held by kworker/u4:8/9923:
 #0: ffff8880b903a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xa5/0x140 kernel/sched/core.c:483
 #1: ffff8880b9127888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x4d6/0x810 kernel/sched/psi.c:891

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 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+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 155 Comm: kworker/u4:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:__preempt_count_add arch/x86/include/asm/preempt.h:80 [inline]
RIP: 0010:rcu_is_watching+0x5/0xa0 kernel/rcu/tree.c:1122
Code: 65 e8 5b 41 5e 41 5f 5d c3 e8 c7 bc 45 08 41 f7 c7 00 02 00 00 75 b8 eb b7 e8 a7 bc 45 08 0f 1f 80 00 00 00 00 41 57 41 56 53 <65> ff 05 8c be 9e 7e e8 9f cc 45 08 89 c3 83 f8 08 73 5c 49 bf 00
RSP: 0018:ffffc90001ec7a80 EFLAGS: 00000257
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff815bfaab
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8d699d28
RBP: ffffc90001ec7bc0 R08: dffffc0000000000 R09: fffffbfff1ad33a6
R10: fffffbfff1ad33a6 R11: 1ffffffff1ad33a5 R12: ffffffff8c11c760
R13: 1ffff920003d8f60 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005636e216b3d0 CR3: 000000005e116000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 trace_lock_acquire include/trace/events/lock.h:13 [inline]
 lock_acquire+0xcd/0x3f0 kernel/locking/lockdep.c:5594
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
 batadv_nc_worker+0xc9/0x5c0 net/batman-adv/network-coding.c:723
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/15 17:37 linux-5.15.y cc5ec8769306 f7988ea4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in io_uring_del_tctx_node
2025/09/08 18:58 linux-5.15.y 7a6c2d093c45 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in io_uring_del_tctx_node
2025/08/03 14:19 linux-5.15.y c79648372d02 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in io_uring_del_tctx_node
2025/07/24 10:19 linux-5.15.y c79648372d02 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: task hung in io_uring_del_tctx_node
* Struck through repros no longer work on HEAD.