syzbot

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Not in threaded context on PREEMPT_RT as expected
WARNING: kernel/sched/completion.c:76 at complete_all+0x174/0x218 kernel/sched/completion.c:76, CPU#1: syz.2.280/6032
Modules linked in:
CPU: 1 UID: 0 PID: 6032 Comm: syz.2.280 Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026
pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : complete_all+0x174/0x218 kernel/sched/completion.c:76
lr : complete_all+0x174/0x218 kernel/sched/completion.c:76
sp : ffff8000931c7780
x29: ffff8000931c7780 x28: ffff0000f2eacba8 x27: ffff0000c30760a0
x26: 1fffe0001e5d5975 x25: dfff800000000000 x24: ffff700012638f08
x23: 1fffe0001e5d5913 x22: dfff800000000000 x21: ffff0000f2690000
x20: ffff0000f2690b18 x19: ffff0000f2eac8f8 x18: 1fffe00035bf0220
x17: 0000000000000003 x16: ffff800088a0b000 x15: ffff800088abda60
x14: ffff0001adf8110c x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000003 x9 : 868cca7cfbaaab00
x8 : 868cca7cfbaaab00 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff8000803b4ab0
x2 : 0000000000000001 x1 : ffff0000f2690000 x0 : 0000000000000001
Call trace:
 complete_all+0x174/0x218 kernel/sched/completion.c:76 (P)
 device_pm_remove+0x74/0x2b0 drivers/base/power/main.c:172
 device_del+0x3f4/0x71c drivers/base/core.c:3896
 netdev_unregister_kobject+0x2a8/0x39c net/core/net-sysfs.c:2314
 unregister_netdevice_many_notify+0x13d8/0x18f4 net/core/dev.c:12456
 unregister_netdevice_many net/core/dev.c:12484 [inline]
 unregister_netdevice_queue+0x274/0x30c net/core/dev.c:12294
 unregister_netdevice include/linux/netdevice.h:3444 [inline]
 __tun_detach+0x814/0xec8 drivers/net/tun.c:621
 tun_detach drivers/net/tun.c:637 [inline]
 tun_chr_close+0x118/0x1f4 drivers/net/tun.c:3441
 __fput+0x338/0x74c fs/file_table.c:510
 ____fput+0x20/0x30 fs/file_table.c:538
 task_work_run+0x1cc/0x25c kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline]
 el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:737
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594
irq event stamp: 11400
hardirqs last  enabled at (11399): [<ffff8000803b4a78>] raw_spin_rq_unlock_irq kernel/sched/sched.h:1644 [inline]
hardirqs last  enabled at (11399): [<ffff8000803b4a78>] finish_lock_switch kernel/sched/core.c:5125 [inline]
hardirqs last  enabled at (11399): [<ffff8000803b4a78>] finish_task_switch+0x234/0x7b8 kernel/sched/core.c:5243
hardirqs last disabled at (11400): [<ffff80008682e34c>] el1_brk64+0x20/0x54 arch/arm64/kernel/entry-common.c:425
softirqs last  enabled at (11374): [<ffff80008030c57c>] softirq_handle_end kernel/softirq.c:468 [inline]
softirqs last  enabled at (11374): [<ffff80008030c57c>] handle_softirqs+0xc28/0xd98 kernel/softirq.c:650
softirqs last disabled at (11213): [<ffff8000800204b0>] __do_softirq+0x14/0x20 kernel/softirq.c:656
---[ end trace 0000000000000000 ]---