syzbot

watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [kworker/0:2:20588]
Modules linked in:
irq event stamp: 1068677
hardirqs last  enabled at (1068676): [<ffff80008a439ebc>] __exit_to_kernel_mode arch/arm64/kernel/entry-common.c:84 [inline]
hardirqs last  enabled at (1068676): [<ffff80008a439ebc>] exit_to_kernel_mode+0xdc/0x10c arch/arm64/kernel/entry-common.c:94
hardirqs last disabled at (1068677): [<ffff80008a437af4>] __el1_irq arch/arm64/kernel/entry-common.c:470 [inline]
hardirqs last disabled at (1068677): [<ffff80008a437af4>] el1_interrupt+0x24/0x68 arch/arm64/kernel/entry-common.c:488
softirqs last  enabled at (1063232): [<ffff800085588484>] pppoe_flush_dev drivers/net/ppp/pppoe.c:327 [inline]
softirqs last  enabled at (1063232): [<ffff800085588484>] pppoe_device_event+0x45c/0x498 drivers/net/ppp/pppoe.c:346
softirqs last disabled at (1063234): [<ffff800088845318>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
CPU: 0 PID: 20588 Comm: kworker/0:2 Not tainted 6.4.0-rc5-syzkaller-g45010c64f1e4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Workqueue: events ser_release
pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : queued_spin_lock_slowpath+0x15c/0xcf8 kernel/locking/qspinlock.c:383
lr : queued_spin_lock_slowpath+0x168/0xcf8 kernel/locking/qspinlock.c:383
sp : ffff8000a4e07560
x29: ffff8000a4e07600 x28: 1fffe00019f70f18 x27: 1ffff000149c0eb8
x26: dfff800000000000 x25: 1fffe00019f70f1a x24: ffff8000a4e07580
x23: ffff8000a4e075c0 x22: ffff7000149c0eb0 x21: 0000000000000001
x20: 0000000000000001 x19: ffff0000cfb878c0 x18: 000000006d3937a8
x17: 000000006bcd35a8 x16: ffff800080997a00 x15: 0000000000000000
x14: 1ffff00011bd80ac x13: dfff800000000000 x12: 0000000000000001
x11: 1fffe00019f70f18 x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000000000000001 x7 : ffff80008883b014 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff80008a522638
x2 : 0000000000000000 x1 : 0000000000000001 x0 : 0000000000000001
Call trace:
 __cmpwait_case_8 arch/arm64/include/asm/cmpxchg.h:249 [inline]
 __cmpwait arch/arm64/include/asm/cmpxchg.h:277 [inline]
 queued_spin_lock_slowpath+0x15c/0xcf8 kernel/locking/qspinlock.c:383
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x320/0x348 kernel/locking/spinlock_debug.c:115
 __raw_spin_lock include/linux/spinlock_api_smp.h:134 [inline]
 _raw_spin_lock+0x50/0x60 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:350 [inline]
 __netif_tx_lock include/linux/netdevice.h:4366 [inline]
 netif_freeze_queues net/sched/sch_generic.c:459 [inline]
 netif_tx_lock+0x9c/0x1d8 net/sched/sch_generic.c:468
 netif_tx_lock_bh include/linux/netdevice.h:4450 [inline]
 dev_watchdog_down net/sched/sch_generic.c:563 [inline]
 dev_deactivate_many+0x274/0x9fc net/sched/sch_generic.c:1340
 __dev_close_many+0x26c/0x3c4 net/core/dev.c:1486
 dev_close_many+0x1e0/0x470 net/core/dev.c:1524
 dev_close+0x174/0x250 net/core/dev.c:1550
 ser_release+0x188/0x238 drivers/net/caif/caif_serial.c:309
 process_one_work+0x788/0x12d4 kernel/workqueue.c:2405
 worker_thread+0x8e0/0xfe8 kernel/workqueue.c:2552
 kthread+0x288/0x310 kernel/kthread.c:379
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:853