[syzbot] [x25?] BUG: sleeping function called from invalid context in x25_kill_by_neigh

Hello,

syzbot found the following issue on:

HEAD commit:    50d05c7c76c9 Merge tag 'landlock-7.3-rc3' of git://git.ker..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14abb749580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b454dc6b1b7acd30
dashboard link: https://syzkaller.appspot.com/bug?extid=9faa82ae2e94c5c7d2ef
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12445ef9580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16445ef9580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7171282977df/disk-50d05c7c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/eb180d9b54d5/vmlinux-50d05c7c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ff1f279b8f9e/bzImage-50d05c7c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9faa82ae2e94c5c7d2ef@syzkaller.appspotmail.com

BUG: sleeping function called from invalid context at net/core/sock.c:3832
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 29, name: ktimers/1
preempt_count: 0, expected: 0
RCU nest depth: 2, expected: 0
locks held by ktimers/1/29: 4, last CPU#1:
 #0: ffffffff8e0594c0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3d/0x420 kernel/softirq.c:186
 #1: ffffffff8e1c3c40 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3d/0x420 kernel/softirq.c:186
 #2: ffffffff8e1c3c40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #2: ffffffff8e1c3c40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #2: ffffffff8e1c3c40 (rcu_read_lock){....}-{1:3}, at: netif_receive_skb_core+0x33/0x2b0 net/core/dev.c:6288
 #3: ffff888038d40358 (sk_lock-AF_X25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
 #3: ffff888038d40358 (sk_lock-AF_X25){+.+.}-{0:0}, at: x25_kill_by_neigh+0x134/0x2a0 net/x25/af_x25.c:1778
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 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 __might_resched+0x31b/0x470 kernel/sched/core.c:9256
 lock_sock_nested+0x56/0x130 net/core/sock.c:3832
 lock_sock include/net/sock.h:1713 [inline]
 x25_kill_by_neigh+0x134/0x2a0 net/x25/af_x25.c:1778
 x25_lapb_receive_frame+0x1b0/0xfb0 net/x25/x25_dev.c:138
 __netif_receive_skb_one_core net/core/dev.c:6264 [inline]
 netif_receive_skb_core+0x2a6/0x2b0 net/core/dev.c:6289
 lapbeth_napi_poll+0x45/0x90 drivers/net/wan/lapbether.c:100
 __napi_poll+0xae/0x550 net/core/dev.c:7787
 napi_poll net/core/dev.c:7850 [inline]
 net_rx_action+0x621/0xd70 net/core/dev.c:8007
 handle_softirqs+0x1da/0x6d0 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 run_ktimerd+0x6a/0x100 kernel/softirq.c:1174
 smpboot_thread_fn+0x565/0xa70 kernel/smpboot.c:160
 kthread+0x38b/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>


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