[v5.15] BUG: soft lockup in handle_softirqs

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 98f47d0e9b8c Linux 5.15.184
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16f0c570580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9eb2b5a65dfc4761
dashboard link: https://syzkaller.appspot.com/bug?extid=d252d131ec097dffa44f
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d2845fb3af6c/disk-98f47d0e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1f12b743be24/vmlinux-98f47d0e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f178b57ea38/Image-98f47d0e.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d252d1...@syzkaller.appspotmail.com

watchdog: BUG: soft lockup - CPU#0 stuck for 38s! [kworker/u4:1:136]
Modules linked in:
irq event stamp: 394057
hardirqs last enabled at (394056): [<ffff80000f7180f0>] process_backlog+0x664/0x744 net/core/dev.c:6542
hardirqs last disabled at (394057): [<ffff8000111a3e04>] enter_el1_irq_or_nmi+0x10/0x1c arch/arm64/kernel/entry-common.c:227
softirqs last enabled at (394040): [<ffff80000f6ed3c4>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:31
softirqs last disabled at (394041): [<ffff80000819c5d8>] __do_softirq kernel/softirq.c:592 [inline]
softirqs last disabled at (394041): [<ffff80000819c5d8>] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
softirqs last disabled at (394041): [<ffff80000819c5d8>] do_softirq+0xfc/0x1b0 kernel/softirq.c:459
CPU: 0 PID: 136 Comm: kworker/u4:1 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : process_backlog+0x66c/0x744 net/core/dev.c:6511
lr : process_backlog+0x664/0x744 net/core/dev.c:6542
sp : ffff80001bd673f0
x29: ffff80001bd67460 x28: ffff0001a110fb78 x27: ffff0001a110fbe0
x26: 0000000000000000 x25: 0000000000000001 x24: dfff800000000000
x23: ffff0001a110fbe0 x22: ffff0001a110fb00 x21: ffff0001a110fa20
x20: ffff0001a110fa10 x19: ffff0001a110fb78 x18: 0000000000000101
x17: 0000000000000000 x16: ffff8000082bf2b8 x15: 0000000000000001
x14: 00000000ffff8000 x13: 1ffff0000282a06b x12: 0000000000ff0100
x11: 0000000000000101 x10: 0000000000000003 x9 : 0000000000000000
x8 : 00000000000000e0 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000000 x3 : ffff800008044e7c
x2 : 0000000000000002 x1 : ffff8000112fb080 x0 : ffff80018d058000
Call trace:
arch_local_irq_enable arch/arm64/include/asm/irqflags.h:35 [inline]
process_backlog+0x66c/0x744 net/core/dev.c:6542
__napi_poll+0xb4/0x5dc net/core/dev.c:7075
napi_poll net/core/dev.c:7142 [inline]
net_rx_action+0x468/0xa08 net/core/dev.c:7232
handle_softirqs+0x344/0xbf0 kernel/softirq.c:558
__do_softirq kernel/softirq.c:592 [inline]
do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
do_softirq+0xfc/0x1b0 kernel/softirq.c:459
__local_bh_enable_ip+0x250/0x380 kernel/softirq.c:383
local_bh_enable+0x28/0x34 include/linux/bottom_half.h:32
rcu_read_unlock_bh include/linux/rcupdate.h:809 [inline]
__dev_queue_xmit+0x11c0/0x2800 net/core/dev.c:4315
dev_queue_xmit+0x24/0x34 net/core/dev.c:4321
batadv_send_skb_packet+0x284/0x4c0 net/batman-adv/send.c:108
batadv_send_broadcast_skb+0x30/0x40 net/batman-adv/send.c:127
batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:392 [inline]
batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline]
batadv_iv_send_outstanding_bat_ogm_packet+0x670/0x858 net/batman-adv/bat_iv_ogm.c:1700
process_one_work+0x79c/0x1140 kernel/workqueue.c:2310
worker_thread+0x8f4/0x101c kernel/workqueue.c:2457
kthread+0x374/0x454 kernel/kthread.c:334
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870


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[syzbot]

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