[syzbot] [net?] INFO: task hung in nsim_destroy (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4a4be1ad3a6e Revert "vfs: Delete the associated dentry whe..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14e37be6980000
kernel config: https://syzkaller.appspot.com/x/.config?x=238430243a58f702
dashboard link: https://syzkaller.appspot.com/bug?extid=8141dcbd23a8f857798a
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b1ea85ab1f5b/disk-4a4be1ad.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/681d06438c4b/vmlinux-4a4be1ad.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9f422d33e089/bzImage-4a4be1ad.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8141dc...@syzkaller.appspotmail.com

INFO: task kworker/u8:10:2466 blocked for more than 143 seconds.
Not tainted 6.10.0-rc1-syzkaller-00027-g4a4be1ad3a6e #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:10 state:D stack:24624 pid:2466 tgid:2466 ppid:2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5408 [inline]
__schedule+0xf15/0x5d00 kernel/sched/core.c:6745
__schedule_loop kernel/sched/core.c:6822 [inline]
schedule+0xe7/0x350 kernel/sched/core.c:6837
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6894
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752
nsim_destroy+0x6f/0x6a0 drivers/net/netdevsim/netdev.c:772
__nsim_dev_port_del+0x189/0x240 drivers/net/netdevsim/dev.c:1425
nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1437 [inline]
nsim_dev_reload_destroy+0x108/0x4d0 drivers/net/netdevsim/dev.c:1658
nsim_dev_reload_down+0x6e/0xd0 drivers/net/netdevsim/dev.c:965
devlink_reload+0x19a/0x7c0 net/devlink/dev.c:461
devlink_pernet_pre_exit+0x1a1/0x2b0 net/devlink/core.c:509
ops_pre_exit_list net/core/net_namespace.c:163 [inline]
cleanup_net+0x488/0xbf0 net/core/net_namespace.c:620
process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231
process_scheduled_works kernel/workqueue.c:3312 [inline]
worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
INFO: task kworker/1:4:5158 blocked for more than 143 seconds.
Not tainted 6.10.0-rc1-syzkaller-00027-g4a4be1ad3a6e #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:4 state:D stack:24768 pid:5158 tgid:5158 ppid:2 flags:0x00004000
Workqueue: events linkwatch_event
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5408 [inline]
__schedule+0xf15/0x5d00 kernel/sched/core.c:6745
__schedule_loop kernel/sched/core.c:6822 [inline]
schedule+0xe7/0x350 kernel/sched/core.c:6837
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6894
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752
linkwatch_event+0x51/0xc0 net/core/link_watch.c:276
process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231
process_scheduled_works kernel/workqueue.c:3312 [inline]
worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
#0: ffffffff8dbb18e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
#0: ffffffff8dbb18e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
#0: ffffffff8dbb18e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x75/0x340 kernel/locking/lockdep.c:6614


---
This report is generated by a bot. It may contain errors.
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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 3a8660878839 Linux 6.18-rc1
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11b5867c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=af9170887d81dea1
dashboard link: https://syzkaller.appspot.com/bug?extid=8141dcbd23a8f857798a
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133e2dcd980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fd8d149698dd/disk-3a866087.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3821c26bbc7b/vmlinux-3a866087.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8c9814247a19/bzImage-3a866087.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8141dc...@syzkaller.appspotmail.com

INFO: task kworker/u8:17:6162 blocked for more than 143 seconds.
Not tainted syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:kworker/u8:17 state:D stack:23272 pid:6162 tgid:6162 ppid:2 task_flags:0x4208060 flags:0x00080000

Workqueue: netns cleanup_net
Call Trace:
<TASK>

context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7307
rt_mutex_slowlock_block+0x5ba/0x6d0 kernel/locking/rtmutex.c:1647
__rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
rt_mutex_slowlock+0x2b1/0x6e0 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
__mutex_lock_common kernel/locking/rtmutex_api.c:536 [inline]
mutex_lock_nested+0x16a/0x1d0 kernel/locking/rtmutex_api.c:547
nsim_destroy+0xe5/0x670 drivers/net/netdevsim/netdev.c:1166
__nsim_dev_port_del+0x14d/0x1b0 drivers/net/netdevsim/dev.c:1473
nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1485 [inline]
nsim_dev_reload_destroy+0x288/0x490 drivers/net/netdevsim/dev.c:1707
nsim_dev_reload_down+0x8a/0xc0 drivers/net/netdevsim/dev.c:983
devlink_reload+0x1b6/0x8d0 net/devlink/dev.c:461
devlink_pernet_pre_exit+0x1d9/0x3d0 net/devlink/core.c:509
ops_pre_exit_list net/core/net_namespace.c:161 [inline]
ops_undo_list+0x187/0x990 net/core/net_namespace.c:234
cleanup_net+0x4de/0x820 net/core/net_namespace.c:695
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
INFO: task syz-executor:6187 blocked for more than 144 seconds.
Not tainted syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:syz-executor state:D stack:22296 pid:6187 tgid:6187 ppid:1 task_flags:0x400140 flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7307
rt_mutex_slowlock_block+0x5ba/0x6d0 kernel/locking/rtmutex.c:1647
__rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
rt_mutex_slowlock+0x2b1/0x6e0 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
__mutex_lock_common kernel/locking/rtmutex_api.c:536 [inline]
mutex_lock_nested+0x16a/0x1d0 kernel/locking/rtmutex_api.c:547
rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978
rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6954
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x846/0xa10 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
__sys_sendto+0x3c7/0x520 net/socket.c:2244
__do_sys_sendto net/socket.c:2251 [inline]
__se_sys_sendto net/socket.c:2247 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2247
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0c4ff50d5c
RSP: 002b:00007ffd595a73c0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f0c50cd4620 RCX: 00007f0c4ff50d5c
RDX: 0000000000000028 RSI: 00007f0c50cd4670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffd595a7414 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f0c50cd4670 R15: 0000000000000000
</TASK>
INFO: task syz-executor:6193 blocked for more than 145 seconds.
Not tainted syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:syz-executor state:D stack:23880 pid:6193 tgid:6193 ppid:1 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7307
rt_mutex_slowlock_block+0x5ba/0x6d0 kernel/locking/rtmutex.c:1647
__rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
rt_mutex_slowlock+0x2b1/0x6e0 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
__mutex_lock_common kernel/locking/rtmutex_api.c:536 [inline]
mutex_lock_nested+0x16a/0x1d0 kernel/locking/rtmutex_api.c:547
rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978
rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6954
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x846/0xa10 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
__sys_sendto+0x3c7/0x520 net/socket.c:2244
__do_sys_sendto net/socket.c:2251 [inline]
__se_sys_sendto net/socket.c:2247 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2247
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3b815f0d5c
RSP: 002b:00007ffe5d47dc20 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f3b82374620 RCX: 00007f3b815f0d5c
RDX: 0000000000000028 RSI: 00007f3b82374670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffe5d47dc74 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f3b82374670 R15: 0000000000000000

</TASK>

Showing all locks held in the system:

1 lock held by init/1:
2 locks held by kworker/0:0/9:
4 locks held by kworker/0:1/10:
#0: ffff88813fe1a138 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88813fe1a138 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc900000f7ba0 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc900000f7ba0 ((reg_check_chans).work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: reg_check_chans_work+0xa1/0xf40 net/wireless/reg.c:2453
#3: ffff8880592a08b8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6358 [inline]
#3: ffff8880592a08b8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: reg_leave_invalid_chans net/wireless/reg.c:2441 [inline]
#3: ffff8880592a08b8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: reg_check_chans_work+0x170/0xf40 net/wireless/reg.c:2456
5 locks held by kworker/u8:0/12:
3 locks held by kworker/u8:1/13:
4 locks held by pr/legacy/17:
2 locks held by ktimers/1/29:
#0: ffff8880b893add8 (&rq->__lock){-...}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:638
#1: ffff8880b8924148 (psi_seq){-...}-{0:0}, at: psi_task_switch+0x53/0x880 kernel/sched/psi.c:933
1 lock held by khungtaskd/38:
#0: ffffffff8d7aa4c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8d7aa4c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8d7aa4c0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
8 locks held by kworker/u8:2/43:
5 locks held by kworker/u8:3/58:
4 locks held by kworker/u8:5/150:
5 locks held by kworker/u8:6/186:
3 locks held by kworker/0:2/994:
3 locks held by kworker/u8:7/1018:
#0: ffff88802f988938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88802f988938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc9000483fba0 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc9000483fba0 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#2: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x119/0x15a0 net/ipv6/addrconf.c:4194
8 locks held by kworker/u8:8/1120:
4 locks held by kworker/u8:9/1171:
3 locks held by kworker/u8:10/1308:
5 locks held by kworker/u8:11/1356:
1 lock held by klogd/5157:
4 locks held by udevd/5168:
1 lock held by dhcpcd/5464:
2 locks held by getty/5562:
#0: ffff88823bf860a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x444/0x1400 drivers/tty/n_tty.c:2222
4 locks held by syz-execprog/5828:
1 lock held by syz-executor/5835:
1 lock held by syz-executor/5942:
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3436
1 lock held by syz-executor/5944:
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3436
2 locks held by kworker/u8:13/6140:
6 locks held by kworker/u8:14/6150:
4 locks held by kworker/u8:15/6157:
3 locks held by kworker/u8:16/6158:
6 locks held by kworker/u8:17/6162:
#0: ffff88801a294938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88801a294938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc90003ab7ba0 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc90003ab7ba0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffffffff8ea6a9e0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x820 net/core/net_namespace.c:669
#3:
ffff8880352f40d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline]
ffff8880352f40d8 (&dev->mutex){....}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:108 [inline]
ffff8880352f40d8 (&dev->mutex){....}-{4:4}, at: devlink_pernet_pre_exit+0x10a/0x3d0 net/devlink/core.c:506
#4: ffff888033c70300 (&devlink->lock_key#5){+.+.}-{4:4}, at: devl_lock net/devlink/core.c:276 [inline]
#4: ffff888033c70300 (&devlink->lock_key#5){+.+.}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:109 [inline]
#4: ffff888033c70300 (&devlink->lock_key#5){+.+.}-{4:4}, at: devlink_pernet_pre_exit+0x11c/0x3d0 net/devlink/core.c:506
#5: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: nsim_destroy+0xe5/0x670 drivers/net/netdevsim/netdev.c:1166
1 lock held by syz-executor/6187:
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978
1 lock held by syz-executor/6193:
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978
3 locks held by kworker/u8:20/6204:
1 lock held by syz.4.53/6206:
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
#0: ffffffff8ea778f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3436
4 locks held by kworker/u8:21/6212:
5 locks held by kworker/u8:22/6215:
4 locks held by syz-executor/6243:
#0: ffff88805ac08e88 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:499 [inline]
#0: ffff88805ac08e88 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x212/0x510 net/bluetooth/hci_core.c:2715
#1: ffff88805ac080a8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x66a/0x1330 net/bluetooth/hci_sync.c:5291
#2: ffffffff8ebdee38 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2118 [inline]
#2: ffffffff8ebdee38 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xa1/0x230 net/bluetooth/hci_conn.c:2602
#3: ffff888024033358 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x70/0x680 net/bluetooth/l2cap_core.c:1762
2 locks held by syz-executor/6246:
#0: ffff888038751d08 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1a3/0x450 mm/mmap_lock.c:238
#1: ffff88813fffc5d8 (&zone->lock){+.+.}-{3:3}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:638
2 locks held by syz-executor/6249:
1 lock held by syz-executor/6253:
2 locks held by dhcpcd/6252:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf60/0xfa0 kernel/hung_task.c:495
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 29 Comm: ktimers/1 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:trace_hardirqs_on+0x18/0x40 kernel/trace/trace_preemptirq.c:75
Code: 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 65 8b 05 e5 cf ff 0f 85 c0 74 14 48 8b 3c 24 e8 c8 fe ff ff <65> c7 05 cd cf ff 0f 00 00 00 00 e8 d8 56 d5 ff 48 8b 3c 24 e9 8f
RSP: 0000:ffffc90000a3fc38 EFLAGS: 00000002
RAX: 0000000000000001 RBX: ffff88801c2e294c RCX: cebf1c97ee368100
RDX: 0000000000000000 RSI: ffffffff8b3f4d40 RDI: ffffffff8b3f4d00
RBP: ffffc90000a3fcd0 R08: ffffffff8ef76677 R09: 1ffffffff1deecce
R10: dffffc0000000000 R11: fffffbfff1deeccf R12: 0000000000000000
R13: ffff88801c2e3560 R14: 1ffff92000147f88 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888126cc9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3b12462600 CR3: 000000003c378000 CR4: 00000000003526f0
Call Trace:
<TASK>
ksoftirqd_run_end kernel/softirq.c:327 [inline]
run_ktimerd+0x131/0x190 kernel/softirq.c:1140
smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: b85966adbf5d Merge tag 'net-next-7.2' of git://git.kernel...
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11f167b6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9a9f723a32776544
dashboard link: https://syzkaller.appspot.com/bug?extid=8141dcbd23a8f857798a
compiler: Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15cf400a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1013a50e580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d65306d96573/disk-b85966ad.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ef43139aab0e/vmlinux-b85966ad.xz
kernel image: https://storage.googleapis.com/syzbot-assets/26d4d1ab67c3/bzImage-b85966ad.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8141dc...@syzkaller.appspotmail.com

INFO: task kworker/R-netns:8 blocked for more than 140 seconds.
Not tainted syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:kworker/R-netns state:D stack:27768 pid:8 tgid:8 ppid:2 task_flags:0x4208060 flags:0x00080000

Workqueue: netns cleanup_net
Call Trace:
<TASK>

context_switch kernel/sched/core.c:5504 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7228
__schedule_loop kernel/sched/core.c:7307 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7322
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7379
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7bf/0x1550 kernel/locking/mutex.c:821
rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
rtnl_net_dev_lock+0x257/0x2f0 net/core/dev.c:2163
unregister_netdevice_notifier_dev_net+0x96/0x450 net/core/dev.c:2208
nsim_destroy+0xfd/0x800 drivers/net/netdevsim/netdev.c:1183
__nsim_dev_port_del+0x14e/0x200 drivers/net/netdevsim/dev.c:1547
nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1561 [inline]
nsim_dev_reload_destroy+0x288/0x490 drivers/net/netdevsim/dev.c:1785
nsim_dev_reload_down+0x8a/0xc0 drivers/net/netdevsim/dev.c:1038
devlink_reload+0x1c5/0x890 net/devlink/dev.c:462
devlink_pernet_pre_exit+0x1ff/0x420 net/devlink/core.c:560
ops_pre_exit_list net/core/net_namespace.c:161 [inline]
ops_undo_list+0x17d/0x8d0 net/core/net_namespace.c:234
cleanup_net+0x572/0x810 net/core/net_namespace.c:702
process_one_work kernel/workqueue.c:3314 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397
rescuer_thread+0x7b6/0x10b0 kernel/workqueue.c:3621
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
INFO: task kworker/0:1:10 blocked for more than 142 seconds.
Not tainted syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:kworker/0:1 state:D stack:27096 pid:10 tgid:10 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: events request_firmware_work_func
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5504 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7228
__schedule_loop kernel/sched/core.c:7307 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7322
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7379
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7bf/0x1550 kernel/locking/mutex.c:821
regdb_fw_cb+0x7d/0x1c0 net/wireless/reg.c:1005
request_firmware_work_func+0xf2/0x1a0 drivers/base/firmware_loader/main.c:1152
process_one_work kernel/workqueue.c:3314 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3478
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
INFO: task kworker/u8:0:12 blocked for more than 143 seconds.
Not tainted syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:kworker/u8:0 state:D stack:23864 pid:12 tgid:12 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5504 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7228
__schedule_loop kernel/sched/core.c:7307 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7322
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7379
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7bf/0x1550 kernel/locking/mutex.c:821
rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
addrconf_dad_work+0x116/0x15c0 net/ipv6/addrconf.c:4223
</TASK>
INFO: task syz-executor831:5632 blocked for more than 144 seconds.
Not tainted syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:syz-executor831 state:R running task stack:22336 pid:5632 tgid:5632 ppid:5629 task_flags:0x400140 flags:0x00080000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5504 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7228
</TASK>
INFO: lockdep is turned off.

NMI backtrace for cpu 1

CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xfd7/0x1030 kernel/hung_task.c:561
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 1 to CPUs 0:

NMI backtrace for cpu 0

CPU: 0 UID: 0 PID: 808 Comm: kworker/0:2 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: wg-crypt-wg0 wg_packet_encrypt_worker
RIP: 0010:memset_orig+0x25/0xb0 arch/x86/lib/memset_64.S:64
Code: 90 90 90 90 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01 01 01 48 0f af c1 41 89 f9 41 83 e1 07 75 74 48 89 d1 48 c1 e9 06 <74> 39 66 0f 1f 84 00 00 00 00 00 48 ff c9 48 89 07 48 89 47 08 48
RSP: 0018:ffffc90000006f20 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc90000007078 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc90000007078
RBP: 1ffffffff2189698 R08: ffffc90000007087 R09: 0000000000000000
R10: ffffc90000007078 R11: fffff52000000e11 R12: dffffc0000000000
R13: ffffffff90c4b4c0 R14: ffffc90000007028 R15: ffffc90000007070
FS: 0000000000000000(0000) GS:ffff88812527c000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 000055968609b450 CR3: 000000000e746000 CR4: 00000000003526f0
Call Trace:
<IRQ>
unwind_next_frame+0xd04/0x2550 arch/x86/kernel/unwind_orc.c:621
__unwind_start+0x514/0x660 arch/x86/kernel/unwind_orc.c:787
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xe3/0x150 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2700 [inline]
slab_free mm/slub.c:6310 [inline]
kmem_cache_free+0x182/0x650 mm/slub.c:6437
nft_synproxy_eval_v4+0x383/0x530 net/netfilter/nft_synproxy.c:61
nft_synproxy_do_eval+0x335/0x550 net/netfilter/nft_synproxy.c:142
expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
nft_do_chain+0x48d/0x1b10 net/netfilter/nf_tables_core.c:285
nft_do_chain_inet+0x360/0x4b0 net/netfilter/nft_chain_filter.c:162
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook include/linux/netfilter.h:273 [inline]
NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:316
NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318
__netif_receive_skb_one_core net/core/dev.c:6206 [inline]
__netif_receive_skb net/core/dev.c:6319 [inline]
process_backlog+0xa34/0x1860 net/core/dev.c:6670
__napi_poll+0xaa/0x330 net/core/dev.c:7729
napi_poll net/core/dev.c:7792 [inline]
net_rx_action+0x61d/0xf50 net/core/dev.c:7949
handle_softirqs+0x225/0x840 kernel/softirq.c:622
do_softirq+0x76/0xd0 kernel/softirq.c:523
</IRQ>
<TASK>
__local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450
spin_unlock_bh include/linux/spinlock.h:396 [inline]
ptr_ring_consume_bh include/linux/ptr_ring.h:393 [inline]
wg_packet_encrypt_worker+0x16e2/0x1760 drivers/net/wireguard/send.c:293
process_one_work kernel/workqueue.c:3314 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3478
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.314 msecs