syzbot


INFO: task hung in io_wq_put_and_exit

Status: upstream: reported syz repro on 2025/06/25 22:50
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+ea8018030af6aec75b1e@syzkaller.appspotmail.com
First crash: 54d, last: 9d02h
Fix commit to backport (bisect log) :
tree: upstream
commit bcb0fda3c2da9fe4721d3e73d80e778c038e7d27
Author: Jens Axboe <axboe@kernel.dk>
Date: Wed Mar 5 21:03:34 2025 +0000

  io_uring/rw: ensure reissue path is correctly handled for IOPOLL

  
Bug presence (2)
Date Name Commit Repro Result
2025/06/28 linux-6.6.y (ToT) 3f5b4c104b7d C [report] INFO: task hung in io_wq_put_and_exit
2025/06/28 upstream (ToT) aaf724ed6926 C Didn't crash
Similar bugs (7)
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 C error 10 1d16h 1d10h 0/29 upstream: reported C repro on 2025/08/18 08:05
linux-5.15 INFO: task hung in io_wq_put_and_exit 1 1 526d 526d 0/3 auto-obsoleted due to no activity on 2024/06/19 08:55
upstream INFO: task hung in io_wq_put_and_exit (3) io-uring 1 C error unreliable 75 850d 1245d 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 C unreliable 628 1379d 1440d 20/29 fixed on 2021/11/10 00:50
upstream INFO: task hung in io_wq_put_and_exit (2) fs 1 22 1348d 1377d 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 C done 9 8d05h 27d 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 C unreliable 86 74d 303d 28/29 fixed on 2025/06/10 16:19
Last patch testing requests (2)
Created Duration User Patch Repo Result
2025/08/11 15:38 51m sumanth.gavini@yahoo.com patch linux-6.6.y report log
2025/08/10 21:45 23m sumanth.gavini@yahoo.com patch linux-6.6.y report log
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.4.21:6112 blocked for more than 143 seconds.
      Not tainted 6.6.101-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.21        state:D stack:25448 pid:6112  ppid:6076   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x9b/0x280 kernel/time/timer.c:2143
 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+0x2bd/0x590 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1266 [inline]
 io_wq_put_and_exit+0x2f3/0x660 io_uring/io-wq.c:1294
 io_uring_clean_tctx+0x120/0x190 io_uring/tctx.c:204
 io_uring_cancel_generic+0x5f8/0x6a0 io_uring/io_uring.c:3506
 io_uring_files_cancel include/linux/io_uring.h:69 [inline]
 do_exit+0x5a7/0x23c0 kernel/exit.c:829
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
 get_signal+0x12fc/0x1400 kernel/signal.c:2902
 arch_do_signal_or_restart+0x96/0x780 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f33aeb8ebe9
RSP: 002b:00007f33afa570e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f33aedb6098 RCX: 00007f33aeb8ebe9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f33aedb6098
RBP: 00007f33aedb6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f33aedb6128 R14: 00007fffeaed6510 R15: 00007fffeaed65f8
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/1:1/27:
 #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90000a2fd00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90000a2fd00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff888030631240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x26c/0x3170 drivers/net/netdevsim/fib.c:1491
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2fba0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2fba0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2fba0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
3 locks held by kworker/u4:2/34:
 #0: ffff88802cd89d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff88802cd89d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90000aafd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90000aafd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffffffff8dfbb888 (rtnl_mutex){+.+.}-{3:3}
, at: addrconf_dad_work+0xd0/0x14e0 net/ipv6/addrconf.c:4159
3 locks held by kworker/u5:0/50:
 #0: ffff88806429b538 ((wq_completion)hci10){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff88806429b538 ((wq_completion)hci10){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90000bafd00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90000bafd00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff88807ca7ce70 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x1d4/0x390 net/bluetooth/hci_sync.c:326
2 locks held by kworker/1:2/966:
3 locks held by kworker/u4:6/1126:
 #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc900045ffd00 ((linkwatch_work).work){+.+.}-{0:0}
, at: process_one_work kernel/workqueue.c:2609 [inline]
, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffffffff8dfbb888 (rtnl_mutex){+.+.}-{3:3}
, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:286
2 locks held by kworker/u4:8/1309:
2 locks held by getty/5550:
 #0: ffff88814c9130a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
7 locks held by syz-executor/7214:
1 lock held by syz-executor/7246:
 #0: ffffffff8dfbb888 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8dfbb888 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6472

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.6.101-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 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+0xf41/0xf80 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: 7214 Comm: syz-executor Not tainted 6.6.101-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x2e/0x60 kernel/kcov.c:216
Code: 48 8b 04 24 65 48 8b 0d 60 24 7e 7e 65 8b 15 61 24 7e 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 <74> 2c 8b 91 f8 15 00 00 83 fa 02 75 21 48 8b 91 00 16 00 00 48 8b
RSP: 0018:ffffc90000007370 EFLAGS: 00000246
RAX: ffffffff813aa799 RBX: ffffffff8ec2ddf8 RCX: ffff88802660bc00
RDX: 0000000000000100 RSI: ffffffff8a61cc0f RDI: ffffffff8a61cc4b
RBP: ffffffff8ec2ddf4 R08: ffffc90000007510 R09: 0000000000000014
R10: 0000000000000004 R11: 0000000000000100 R12: ffffffff8ec2ddf4
R13: ffffffff8a61cc4b R14: ffffffff8a61cc0f R15: ffffffff8ec2ddfc
FS:  00005555802a5500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0e5b9185b0 CR3: 000000004ee49000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 __orc_find arch/x86/kernel/unwind_orc.c:99 [inline]
 orc_find arch/x86/kernel/unwind_orc.c:227 [inline]
 unwind_next_frame+0x4d9/0x2970 arch/x86/kernel/unwind_orc.c:494
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3485 [inline]
 kmem_cache_alloc_node+0x150/0x330 mm/slub.c:3530
 __alloc_skb+0x108/0x2c0 net/core/skbuff.c:640
 skb_copy+0x13d/0x7a0 net/core/skbuff.c:1983
 mac80211_hwsim_tx_frame_no_nl+0xc81/0x1170 drivers/net/wireless/virtual/mac80211_hwsim.c:1840
 mac80211_hwsim_tx_frame+0x1b5/0x200 drivers/net/wireless/virtual/mac80211_hwsim.c:2176
 mac80211_hwsim_beacon_tx+0x3e9/0x780 drivers/net/wireless/virtual/mac80211_hwsim.c:2269
 __iterate_interfaces+0x243/0x500 net/mac80211/util.c:766
 ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:802
 mac80211_hwsim_beacon+0xbb/0x1b0 drivers/net/wireless/virtual/mac80211_hwsim.c:2295
 __run_hrtimer kernel/time/hrtimer.c:1755 [inline]
 __hrtimer_run_queues+0x51e/0xc40 kernel/time/hrtimer.c:1819
 hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1836
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:console_trylock_spinning kernel/printk/printk.c:2008 [inline]
RIP: 0010:vprintk_emit+0x44f/0x600 kernel/printk/printk.c:2340
Code: 51 01 00 00 e8 12 4b 1b 00 45 89 f7 48 85 db 48 8b 5c 24 08 75 07 e8 00 4b 1b 00 eb 06 e8 f9 4a 1b 00 fb 48 c7 c7 e0 3e d2 8c <31> f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00 45 31 c9 53 e8 69 bd
RSP: 0018:ffffc9000def6a20 EFLAGS: 00000293
RAX: ffffffff816a4a97 RBX: ffffffff816a4951 RCX: ffff88802660bc00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8cd23ee0
RBP: ffffc9000def6b10 R08: ffffffff90da35e7 R09: 1ffffffff21b46bc
R10: dffffc0000000000 R11: fffffbfff21b46bd R12: dffffc0000000000
R13: ffffc9000def6b80 R14: 000000000000005d R15: 000000000000005d
 _printk+0xd0/0x110 kernel/printk/printk.c:2366
 batadv_check_known_mac_addr+0x29b/0x3e0 net/batman-adv/hard-interface.c:526
 batadv_hard_if_event+0x3a3/0x15b0 net/batman-adv/hard-interface.c:998
 notifier_call_chain+0x197/0x390 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
 call_netdevice_notifiers net/core/dev.c:2078 [inline]
 dev_set_mac_address+0x377/0x4b0 net/core/dev.c:8936
 dev_set_mac_address_user+0x31/0x50 net/core/dev.c:8950
 do_setlink+0x871/0x3fb0 net/core/rtnetlink.c:2860
 __rtnl_newlink net/core/rtnetlink.c:3703 [inline]
 rtnl_newlink+0x175b/0x2020 net/core/rtnetlink.c:3750
 rtnetlink_rcv_msg+0x7c7/0xf10 net/core/rtnetlink.c:6475
 netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2555
 netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1356
 netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1904
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x46a/0x620 net/socket.c:2201
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcc41590a7c
Code: 2a 5f 02 00 44 8b 4c 24 2c 4c 8b 44 24 20 89 c5 44 8b 54 24 28 48 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 <48> 3d 00 f0 ff ff 77 34 89 ef 48 89 44 24 08 e8 70 5f 02 00 48 8b
RSP: 002b:00007ffc7005e9c0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fcc422e4620 RCX: 00007fcc41590a7c
RDX: 000000000000002c RSI: 00007fcc422e4670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffc7005ea14 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007fcc422e4670 R15: 0000000000000000
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/10 16:04 linux-6.6.y 3a8ababb8b6a 32a0e5ed .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in io_wq_put_and_exit
2025/06/25 22:50 linux-6.6.y 6282921b6825 26d77996 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in io_wq_put_and_exit
* Struck through repros no longer work on HEAD.