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: 31d, last: 21d
Similar bugs (5)
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 851d 855d 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 416d 416d 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 87d 83d 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 1267d 1430d 20/29 fixed on 2022/03/08 16:11
upstream INFO: task hung in io_uring_del_tctx_node (2) io-uring 1 C error error 20 895d 1258d 0/29 auto-obsoleted due to no activity on 2023/07/30 22:24

Sample crash report:
INFO: task syz.6.311:5952 blocked for more than 143 seconds.
      Not tainted 5.15.189-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.311       state:D stack:27200 pid: 5952 ppid:  5148 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6518
 __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+0xb1/0x140 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: 0033:0x7f5d12055b69
RSP: 002b:00007f5d0fe9c0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f5d1227d088 RCX: 00007f5d12055b69
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f5d1227d088
RBP: 00007f5d1227d080 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5d1227d08c
R13: 0000000000000000 R14: 00007ffece0d8c70 R15: 00007ffece0d8d58
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
1 lock held by acpid/3545:
 #0: ffffffff8c120de8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #0: ffffffff8c120de8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x320/0x6b0 kernel/rcu/tree_exp.h:845
2 locks held by getty/3944:
 #0: ffff88814d191098 (&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
8 locks held by kworker/1:3/4173:
 #0: ffff8881427e0938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc90002d8fd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff8881485a9220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff8881485a9220 (&dev->mutex){....}-{3:3}, at: hub_event+0x18f/0x4fa0 drivers/usb/core/hub.c:5781
 #3: ffff8880630f1220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #3: ffff8880630f1220 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x107/0x8a0 drivers/usb/core/hub.c:2250
 #4: ffff8880611db1a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #4: ffff8880611db1a8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1044 [inline]
 #4: ffff8880611db1a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb0/0x750 drivers/base/dd.c:1259
 #5: ffffffff8cf07108 (em28xx_devlist_mutex){+.+.}-{3:3}, at: em28xx_close_extension+0x2e/0x210 drivers/media/usb/em28xx/em28xx-core.c:1138
 #6: ffffffff8cd3c0e8 (input_mutex){+.+.}-{3:3}, at: __input_unregister_device+0x10e/0x320 drivers/input/input.c:2280
 #7: ffffffff8c120de8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #7: ffffffff8c120de8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x320/0x6b0 kernel/rcu/tree_exp.h:845
6 locks held by kworker/0:4/4232:
4 locks held by udevd/4340:
 #0: ffff8880585ad790 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xad/0xd50 fs/seq_file.c:182
 #1: ffff888048d20888 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x51/0x3c0 fs/kernfs/file.c:112
 #2: ffff888061a7c1d8 (kn->active#32){++++}-{0:0}, at: kernfs_seq_start+0x71/0x3c0 fs/kernfs/file.c:113
 #3: ffff8880630f1220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #3: ffff8880630f1220 (&dev->mutex){....}-{3:3}, at: uevent_show+0x17a/0x330 drivers/base/core.c:2408
3 locks held by kworker/u4:19/4480:
 #0: ffff888016879138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc900047afd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffffffff8d235f48 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:251
2 locks held by kworker/u4:20/4482:
1 lock held by syz.6.311/5951:
1 lock held by syz.6.311/5952:
 #0: ffff88814cf8c0a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_uring_del_tctx_node+0xe8/0x2c0 io_uring/io_uring.c:9825
1 lock held by syz.7.645/7601:
 #0: ffffffff8d235f48 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:699 [inline]
 #0: ffffffff8d235f48 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3440
4 locks held by syz.0.641/7607:

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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: 7607 Comm: syz.0.641 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:lock_accessed kernel/locking/lockdep.c:1486 [inline]
RIP: 0010:__bfs kernel/locking/lockdep.c:1710 [inline]
RIP: 0010:__bfs_backwards kernel/locking/lockdep.c:1805 [inline]
RIP: 0010:check_irq_usage kernel/locking/lockdep.c:2745 [inline]
RIP: 0010:check_prev_add kernel/locking/lockdep.c:3057 [inline]
RIP: 0010:check_prevs_add kernel/locking/lockdep.c:3172 [inline]
RIP: 0010:validate_chain kernel/locking/lockdep.c:3788 [inline]
RIP: 0010:__lock_acquire+0x30c3/0x7c60 kernel/locking/lockdep.c:5012
Code: 00 00 00 fc ff df 4c 89 b4 24 80 00 00 00 4d 8b 3e 4d 85 ff 0f 84 ab 28 00 00 49 83 c7 4c 4d 89 fc 49 c1 ec 03 41 0f b6 04 14 <84> c0 0f 85 79 03 00 00 44 8b 35 5e 8b a4 10 45 39 37 0f 84 9c fe
RSP: 0018:ffffc9000157e900 EFLAGS: 00000807
RAX: 0000000000000000 RBX: ffffffff929122b8 RCX: dffffc0000000000
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffffff92ad7d08
RBP: ffffc9000157eb50 R08: dffffc0000000000 R09: ffffc9000157eaa0
R10: fffff520002afd5b R11: 1ffff920002afd54 R12: 1ffffffff1f30fa9
R13: 1ffffffff2522459 R14: ffffffff929122c8 R15: ffffffff8f987d4c
FS:  00007f8a38e5a6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8a38e59f98 CR3: 0000000045c51000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 do_write_seqcount_begin_nested include/linux/seqlock.h:519 [inline]
 do_write_seqcount_begin include/linux/seqlock.h:545 [inline]
 psi_group_change+0x113/0x1150 kernel/sched/psi.c:710
 psi_task_switch+0x495/0x810 kernel/sched/psi.c:882
 psi_sched_switch kernel/sched/stats.h:148 [inline]
 __schedule+0x1cef/0x43b0 kernel/sched/core.c:6371
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6780
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:rmqueue_pcplist mm/page_alloc.c:3711 [inline]
RIP: 0010:rmqueue mm/page_alloc.c:3742 [inline]
RIP: 0010:get_page_from_freelist+0x156c/0x1c60 mm/page_alloc.c:4189
Code: 01 00 00 00 00 00 00 9c 8f 84 24 80 01 00 00 f6 84 24 81 01 00 00 02 0f 85 dc 02 00 00 41 f7 c6 00 02 00 00 74 01 fb 4d 85 e4 <48> b9 00 00 00 00 00 fc ff df 4c 8b 74 24 38 0f 84 b9 01 00 00 4c
RSP: 0018:ffffc9000157f160 EFLAGS: 00000286
RAX: efd4db3ec2df2300 RBX: ffffffff8bbbe820 RCX: efd4db3ec2df2300
RDX: dffffc0000000000 RSI: ffffffff8a0b15c0 RDI: ffffffff8a599340
RBP: ffffc9000157f370 R08: dffffc0000000000 R09: fffffbfff1ff6e19
R10: fffffbfff1ff6e19 R11: 1ffffffff1ff6e18 R12: ffffea0001221c00
R13: 0000000000000002 R14: 0000000000000202 R15: ffffc9000157f3c8
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5474
 kmalloc_order+0x40/0x150 mm/slab_common.c:986
 kmalloc_order_trace+0x14/0xf0 mm/slab_common.c:1002
 kmalloc include/linux/slab.h:609 [inline]
 kzalloc include/linux/slab.h:735 [inline]
 vc_allocate+0x445/0x730 drivers/tty/vt/vt.c:1147
 con_install+0xa0/0x700 drivers/tty/vt/vt.c:3382
 tty_driver_install_tty drivers/tty/tty_io.c:1317 [inline]
 tty_init_dev+0xbb/0x470 drivers/tty/tty_io.c:1431
 tty_open_by_driver drivers/tty/tty_io.c:2100 [inline]
 tty_open+0x5b9/0xd20 drivers/tty/tty_io.c:2148
 chrdev_open+0x597/0x670 fs/char_dev.c:414
 do_dentry_open+0x7ff/0xf80 fs/open.c:826
 do_open fs/namei.c:3608 [inline]
 path_openat+0x2682/0x2f30 fs/namei.c:3742
 do_filp_open+0x1b3/0x3e0 fs/namei.c:3769
 do_sys_openat2+0x142/0x4a0 fs/open.c:1253
 do_sys_open fs/open.c:1269 [inline]
 __do_sys_openat fs/open.c:1285 [inline]
 __se_sys_openat fs/open.c:1280 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1280
 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: 0033:0x7f8a3aff14d0
Code: 48 89 44 24 20 75 93 44 89 54 24 0c e8 49 94 02 00 44 8b 54 24 0c 89 da 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 89 44 24 0c e8 9c 94 02 00 8b 44
RSP: 002b:00007f8a38e59b70 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f8a3aff14d0
RDX: 0000000000000002 RSI: 00007f8a38e59c10 RDI: 00000000ffffff9c
RBP: 00007f8a38e59c10 R08: 0000000000000000 R09: 00007f8a38e59987
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f8a3b219fa0 R15: 00007fffc5bb63d8
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.