INFO: task hung in io_wq_put_and_exit

Status: upstream: reported on 2026/08/04 21:15
Reported-by: syzbot+3d7ce2293e62a7d0994b@syzkaller.appspotmail.com
First crash: 1d03h, last: 1d02h
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in io_wq_put_and_exit (6) io-uring 1 syz, C error 74 193d 352d 29/29 fixed on 2026/05/06 16:40
linux-5.15 INFO: task hung in io_wq_put_and_exit 1 1 877d 877d 0/3 auto-obsoleted due to no activity on 2024/06/19 08:55
linux-6.6 INFO: task hung in io_wq_put_and_exit origin:lts-only 1 syz, C done 15 22h21m 406d 0/2 upstream: reported C repro on 2025/06/25 22:50
upstream INFO: task hung in io_wq_put_and_exit (3) io-uring 1 syz, C error unreliable 75 1201d 1596d 0/29 auto-obsoleted due to no activity on 2023/08/20 08:26
upstream INFO: task hung in io_wq_put_and_exit io-uring fs 1 syz, C unreliable 628 1730d 1792d 20/29 fixed on 2021/11/10 00:50
upstream INFO: task hung in io_wq_put_and_exit (2) fs 1 22 1699d 1728d 0/29 closed as invalid on 2022/02/08 09:40
upstream INFO: task hung in io_wq_put_and_exit (5) io-uring input usb 1 syz, C done 9 359d 378d 0/29 closed as invalid on 2025/08/13 14:32
upstream INFO: task hung in io_wq_put_and_exit (4) io-uring 1 syz, C unreliable 86 425d 655d 28/29 fixed on 2025/06/10 16:19

Sample crash report:
INFO: task syz.2.18:4461 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.18        state:D stack:26512 pid:4461  ppid:4283   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2144
 do_wait_for_common kernel/sched/completion.c:85 [inline]
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x2c2/0x590 kernel/sched/completion.c:138
 io_wq_exit_workers io_uring/io-wq.c:1287 [inline]
 io_wq_put_and_exit+0x59d/0xb80 io_uring/io-wq.c:1322
 io_uring_clean_tctx+0x12b/0x19e io_uring/tctx.c:204
 io_uring_cancel_generic+0x59d/0x63c io_uring/io_uring.c:3168
 io_uring_files_cancel include/linux/io_uring.h:54 [inline]
 do_exit+0x5ba/0x2570 kernel/exit.c:833
 do_group_exit+0x229/0x2e0 kernel/exit.c:1030
 get_signal+0x1259/0x1340 kernel/signal.c:2880
 arch_do_signal_or_restart+0xc4/0x1310 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4ce079e019
RSP: 002b:00007f4ce15d90e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f4ce0a25fa8 RCX: 00007f4ce079e019
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f4ce0a25fa8
RBP: 00007f4ce0a25fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4ce0a26038 R14: 00007fff8222efb0 R15: 00007fff8222f098
 </TASK>
INFO: task iou-wrk-4461:4462 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:iou-wrk-4461    state:D stack:25616 pid:4462  ppid:4283   flags:0x00024004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 do_uevent+0x1e9/0x490 fs/dlm/lockspace.c:210
 new_lockspace fs/dlm/lockspace.c:659 [inline]
 __dlm_new_lockspace+0x1d6a/0x22b0 fs/dlm/lockspace.c:719
 device_create_lockspace+0xc4/0x350 fs/dlm/user.c:426
 device_write+0x893/0xea0 fs/dlm/user.c:618
 loop_rw_iter+0x338/0x580 include/linux/uio.h:-1
 io_write+0x119c/0x17a0 io_uring/rw.c:939
 io_issue_sqe+0x28b/0xc90 io_uring/io_uring.c:1747
 io_wq_submit_work+0x40e/0x9c0 io_uring/io_uring.c:1828
 io_worker_handle_work+0x864/0x1190 io_uring/io-wq.c:600
 io_wqe_worker+0x3df/0xed0 io_uring/io-wq.c:645
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2e4f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2ed10 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527
2 locks held by kworker/0:2/1172:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc9000515fd00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
2 locks held by getty/4028:
 #0: ffff88814dd4a098 (&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+0x41e/0x1360 drivers/tty/n_tty.c:2198
3 locks held by kworker/1:4/4317:
 #0: ffff88802e981538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90004137d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xc4/0x1500 net/ipv6/addrconf.c:4138
3 locks held by kworker/0:7/4362:
 #0: ffff88802e981538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90004207d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xc4/0x1500 net/ipv6/addrconf.c:4138
2 locks held by kworker/1:13/4435:
 #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc9000480fd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
1 lock held by iou-wrk-4461/4462:
 #0: ffffffff96d4d888 (&ls_lock){+.+.}-{3:3}, at: __dlm_new_lockspace+0xad/0x22b0 fs/dlm/lockspace.c:713
1 lock held by dlm_recoverd/4467:
 #0: ffff88807ab9cca0 (&ls->ls_in_recovery){+.+.}-{3:3}, at: dlm_recoverd+0xa6/0x1df0 fs/dlm/recoverd.c:312
3 locks held by kworker/1:17/4546:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc9000529fd00 (key_gc_work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
 #2: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3c0/0x890 kernel/rcu/tree_exp.h:962
4 locks held by kworker/u4:12/4968:
 #0: ffff88801761e938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90003747d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd4ead0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x148/0xba0 net/core/net_namespace.c:594
 #3: ffff888035e453e8 (&wg->device_update_lock){+.+.}-{3:3}, at: wg_destruct+0x112/0x300 drivers/net/wireguard/device.c:249
3 locks held by syz-executor/5189:
 #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6163
 #1: ffff8880541d53e8 (&wg->device_update_lock){+.+.}-{3:3}, at: wg_open+0x223/0x420 drivers/net/wireguard/device.c:49
 #2: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
 #2: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2ec/0x890 kernel/rcu/tree_exp.h:962
2 locks held by cmp/5591:

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 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+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 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+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5581 Comm: dhcpcd-run-hook Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:page_remove_rmap+0x9f/0xef0 mm/rmap.c:1428
Code: 83 c4 18 4c 89 e0 48 c1 e8 03 42 80 3c 30 00 74 08 4c 89 e7 e8 d2 0a 0e 00 4d 8b 34 24 44 89 f6 83 e6 01 31 ff e8 e1 e1 bc ff <41> f6 c6 01 48 89 2c 24 0f 85 48 01 00 00 45 84 ed 0f 84 1e 03 00
RSP: 0018:ffffc90003dd7780 EFLAGS: 00000293
RAX: ffffffff81c5501f RBX: ffffea00003e3580 RCX: ffff88802b9f3c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880783d7870 R08: ffff888140058943 R09: 1ffff1102800b128
R10: dffffc0000000000 R11: ffffed102800b129 R12: ffffea00003e3598
R13: 0000000000000000 R14: ffff8880267704d8 R15: 1ffffd400007c6b1
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c0bdfc2138 CR3: 0000000054d27000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 zap_pte_range mm/memory.c:1451 [inline]
 zap_pmd_range mm/memory.c:1572 [inline]
 zap_pud_range mm/memory.c:1601 [inline]
 zap_p4d_range mm/memory.c:1622 [inline]
 unmap_page_range+0x10db/0x25b0 mm/memory.c:1643
 unmap_vmas+0x260/0x390 mm/memory.c:1728
 exit_mmap+0x20d/0x970 mm/mmap.c:3250
 __mmput+0x118/0x3a0 kernel/fork.c:1206
 exit_mm+0x24d/0x350 kernel/exit.c:572
 do_exit+0x958/0x2570 kernel/exit.c:874
 do_group_exit+0x229/0x2e0 kernel/exit.c:1030
 __do_sys_exit_group kernel/exit.c:1041 [inline]
 __se_sys_exit_group kernel/exit.c:1039 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1039
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f28f88766c5
Code: Unable to access opcode bytes at 0x7f28f887669b.
RSP: 002b:00007fff8a624e18 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000055c0bdfac910 RCX: 00007f28f88766c5
RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000
RBP: 00007fff8a625148 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff8a625140
R13: 00007fff8a625150 R14: 00007f28f8a7e000 R15: 000055c0b0bbcd98
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/04 21:15 linux-6.1.y fb28aa725e05 d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in io_wq_put_and_exit
2026/08/04 22:02 linux-6.1.y fb28aa725e05 d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in io_wq_put_and_exit
* Struck through repros no longer work on HEAD.