[syzbot] [kernel?] WARNING in do_notify_parent

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3fa5e5702a82 Add linux-next specific files for 20260227
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16ca68d6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4791940d55a6241f
dashboard link: https://syzkaller.appspot.com/bug?extid=bbe6b99feefc3a0842de
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/68faadb8e3e6/disk-3fa5e570.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4244d0610a6a/vmlinux-3fa5e570.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f95b76890c87/bzImage-3fa5e570.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bbe6b9...@syzkaller.appspotmail.com

------------[ cut here ]------------
!valid_signal(sig)
WARNING: kernel/signal.c:2174 at do_notify_parent+0xc7e/0xd70 kernel/signal.c:2174, CPU#1: syz.1.1187/9757
Modules linked in:
CPU: 1 UID: 0 PID: 9757 Comm: syz.1.1187 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:do_notify_parent+0xc7e/0xd70 kernel/signal.c:2174
Code: c6 05 c4 e5 92 0e 01 48 c7 c7 c0 46 cb 8b be a3 08 00 00 48 c7 c2 40 48 cb 8b e8 ed 52 17 00 e9 c6 fa ff ff e8 23 1f 3b 00 90 <0f> 0b 90 45 31 e4 e9 1c ff ff ff e8 12 1f 3b 00 90 0f 0b 90 e9 75
RSP: 0018:ffffc90003f17c40 EFLAGS: 00010093
RAX: ffffffff818ad72d RBX: dffffc0000000000 RCX: ffff888035061e80
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 0000000000000040
RBP: ffffc90003f17d90 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520007e2fa4 R12: ffff88802eba8010
R13: ffff888035061e80 R14: 0000000000000080 R15: 1ffff920007e2f90
FS: 0000000000000000(0000) GS:ffff888125102000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007faf66e52770 CR3: 000000002cc0a000 CR4: 00000000003526f0
DR0: 0000000000000007 DR1: 0000000000010005 DR2: 000000000000000f
DR3: 0000000000007fff DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
exit_notify kernel/exit.c:756 [inline]
do_exit+0x13f1/0x23c0 kernel/exit.c:986
__do_sys_exit kernel/exit.c:1083 [inline]
__se_sys_exit kernel/exit.c:1081 [inline]
__x64_sys_exit+0x40/0x40 kernel/exit.c:1081
x64_sys_call+0x2231/0x2240 arch/x86/include/generated/asm/syscalls_64.h:61
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7faf66f9c799
Code: Unable to access opcode bytes at 0x7faf66f9c76f.
RSP: 002b:0000200000002818 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 000000000000000b RCX: 00007faf66f9c799
RDX: 00007faf66f9c799 RSI: 0000200000002840 RDI: 000000000000000b
RBP: 00007faf67032bd9 R08: 0000200000002e80 R09: e32a5aa294094ac1
R10: 0000200000002e80 R11: 0000000000000246 R12: 0000000000000000
R13: 00007faf67216038 R14: 00007faf67215fa0 R15: 00007ffe4e1e4898
</TASK>


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