------------[ cut here ]------------
!valid_signal(sig)
WARNING: kernel/signal.c:2174 at do_notify_parent+0xd18/0xe30, CPU#1: syz.2.504/8448
Modules linked in:
CPU: 1 UID: 0 PID: 8448 Comm: syz.2.504 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:do_notify_parent+0xd18/0xe30
Code: c6 05 d0 12 90 0e 01 48 c7 c7 e0 3a cb 8b be a3 08 00 00 48 c7 c2 60 3c cb 8b e8 c3 8c 17 00 e9 2e fa ff ff e8 d9 47 3b 00 90 <0f> 0b 90 45 31 e4 e9 1c ff ff ff e8 c8 47 3b 00 90 0f 0b 90 e9 db
RSP: 0018:ffffc9000857fc40 EFLAGS: 00010093
RAX: ffffffff818a5bd7 RBX: dffffc0000000000 RCX: ffff888177771d80
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 0000000000000040
RBP: ffffc9000857fd90 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520010affa4 R12: ffff88816ccb8790
R13: ffff888177771d80 R14: 0000000000000080 R15: 1ffff920010aff90
FS:  00007fb9838db6c0(0000) GS:ffff8882a9293000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001880 CR3: 00000001772c6000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 do_exit+0x13f1/0x22c0
 __x64_sys_exit+0x40/0x40
 x64_sys_call+0x2231/0x2240
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb98299cdd9
Code: Unable to access opcode bytes at 0x7fb98299cdaf.
RSP: 002b:0000200000001258 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 000000000000000b RCX: 00007fb98299cdd9
RDX: 00007fb98299cdd9 RSI: 0000200000001280 RDI: 000000000000000b
RBP: 00007fb982a32d69 R08: 0000200000001780 R09: 0000000000000000
R10: 0000200000001780 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb982c16038 R14: 00007fb982c15fa0 R15: 00007ffeaee0d498
 </TASK>
