[v6.1] BUG: soft lockup in handle_softirqs

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0bc96de781b4 Linux 6.1.148
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=112d5442580000
kernel config: https://syzkaller.appspot.com/x/.config?x=483f799cd9933afc
dashboard link: https://syzkaller.appspot.com/bug?extid=7d4d67cabbbaf02f49c0
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cd15350f801a/disk-0bc96de7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/789a5d74139d/vmlinux-0bc96de7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a1ef0a7e815a/Image-0bc96de7.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7d4d67...@syzkaller.appspotmail.com

watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [syz.1.564:6668]
Modules linked in:
irq event stamp: 1043483
hardirqs last enabled at (1043482): [<ffff8000083b9464>] seqcount_lockdep_reader_access include/linux/seqlock.h:104 [inline]
hardirqs last enabled at (1043482): [<ffff8000083b9464>] timekeeping_get_delta kernel/time/timekeeping.c:254 [inline]
hardirqs last enabled at (1043482): [<ffff8000083b9464>] timekeeping_get_ns+0x124/0x3b8 kernel/time/timekeeping.c:388
hardirqs last disabled at (1043483): [<ffff800011948df0>] __el1_irq arch/arm64/kernel/entry-common.c:468 [inline]
hardirqs last disabled at (1043483): [<ffff800011948df0>] el1_interrupt+0x24/0x54 arch/arm64/kernel/entry-common.c:486
softirqs last enabled at (3230): [<ffff80000fd32178>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (3231): [<ffff800008020164>] __do_softirq+0x14/0x20 kernel/softirq.c:630
CPU: 1 PID: 6668 Comm: syz.1.564 Not tainted 6.1.148-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 42400005 (nZcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : __sanitizer_cov_trace_pc+0x1c/0x94 kernel/kcov.c:212
lr : cake_heapify+0x30/0x530 net/sched/sch_cake.c:1476
sp : ffff800008017660
x29: ffff800008017680 x28: 1fffe0001ee5f85b x27: ffff000104500000
x26: 000000000003f34f x25: ffff0000f72fc2d8 x24: ffff0000f72f82d0
x23: ffff800008017ca0 x22: ffff0000f72f82c0 x21: ffff0000f72f82c0
x20: 0000000000000000 x19: 00000000000002ab x18: ffff800011aabce0
x17: ffff8000181e7000 x16: ffff8000082d2370 x15: ffff800017cc7fc0
x14: ffff0000c3024218 x13: 1ffff00002a160b1 x12: 0000000000ff0100
x11: ff0080000ffaa1ec x10: 0000000000000102 x9 : ffff80000ffaa1ec
x8 : ffff0000c3023780 x7 : ffff8000083b9870 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000002 x1 : 00000000000002ab x0 : ffff0000f72f82c0
Call trace:
preempt_count arch/arm64/include/asm/preempt.h:13 [inline]
check_kcov_mode kernel/kcov.c:182 [inline]
__sanitizer_cov_trace_pc+0x1c/0x94 kernel/kcov.c:216
cake_drop net/sched/sch_cake.c:1575 [inline]
cake_enqueue+0x333c/0x6880 net/sched/sch_cake.c:1945
qdisc_enqueue include/net/sch_generic.h:816 [inline]
netem_dequeue+0xa74/0x107c net/sched/sch_netem.c:737
dequeue_skb net/sched/sch_generic.c:292 [inline]
qdisc_restart net/sched/sch_generic.c:397 [inline]
__qdisc_run+0x1c4/0x1368 net/sched/sch_generic.c:415
qdisc_run+0xc0/0x228 include/net/pkt_sched.h:126
net_tx_action+0x6c0/0x8c4 net/core/dev.c:5166
handle_softirqs+0x318/0xc6c kernel/softirq.c:596
__do_softirq+0x14/0x20 kernel/softirq.c:630
____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80
call_on_irq_stack+0x24/0x30 arch/arm64/kernel/entry.S:849
do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85
do_softirq+0xf8/0x1ac kernel/softirq.c:497
__local_bh_enable_ip+0x250/0x380 kernel/softirq.c:421
local_bh_enable+0x28/0x34 include/linux/bottom_half.h:33
rcu_read_unlock_bh include/linux/rcupdate.h:861 [inline]
__dev_queue_xmit+0x1704/0x309c net/core/dev.c:4361
dev_queue_xmit include/linux/netdevice.h:3051 [inline]
tipc_l2_send_msg+0x29c/0x35c net/tipc/bearer.c:518
tipc_bearer_xmit_skb+0x244/0x384 net/tipc/bearer.c:577
tipc_disc_reset+0x200/0x2f8 net/tipc/discover.c:419
tipc_reset_bearer+0x5c/0x84 net/tipc/bearer.c:387
tipc_l2_device_event+0x498/0x778 net/tipc/bearer.c:-1
notifier_call_chain kernel/notifier.c:87 [inline]
raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:455
call_netdevice_notifiers_info net/core/dev.c:2001 [inline]
call_netdevice_notifiers_mtu+0x118/0x19c net/core/dev.c:2076
dev_set_mtu_ext+0x350/0x514 net/core/dev.c:8768
dev_set_mtu+0x50/0xe8 net/core/dev.c:8789
dev_ifsioc+0x250/0xed0 net/core/dev_ioctl.c:334
dev_ioctl+0x4c8/0xc8c net/core/dev_ioctl.c:588
sock_do_ioctl+0x18c/0x240 net/socket.c:1218
sock_ioctl+0x5c4/0x840 net/socket.c:1321
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.