------------[ cut here ]------------
!valid_signal(sig)
WARNING: kernel/signal.c:2174 at do_notify_parent+0xd18/0xe30, CPU#1: syz.1.1004/10041
Modules linked in:
CPU: 1 UID: 0 PID: 10041 Comm: syz.1.1004 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 1d 90 0e 01 48 c7 c7 e0 3a cb 8b be a3 08 00 00 48 c7 c2 60 3c cb 8b e8 03 8f 17 00 e9 2e fa ff ff e8 39 55 3b 00 90 <0f> 0b 90 45 31 e4 e9 1c ff ff ff e8 28 55 3b 00 90 0f 0b 90 e9 db
RSP: 0000:ffffc900071a79e0 EFLAGS: 00010093
RAX: ffffffff818a6c97 RBX: dffffc0000000000 RCX: ffff88810dc4bb00
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 0000000000000040
RBP: ffffc900071a7b30 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000e34f58 R12: ffff88810937e910
R13: ffff88810dc4bb00 R14: 0000000000000080 R15: 1ffff92000e34f44
FS:  00007f9f88b1d6c0(0000) GS:ffff8882a928d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00001fffffffff80 CR3: 000000000e74a000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 do_exit+0x13f1/0x22c0
 do_group_exit+0x21b/0x2d0
 get_signal+0x1284/0x1330
 arch_do_signal_or_restart+0xbc/0x840
 irqentry_exit+0x289/0x760
 asm_exc_page_fault+0x26/0x30
RIP: 0033:0xf4f66f
Code: Unable to access opcode bytes at 0xf4f645.
RSP: 002b:00002000000003c8 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f9f87e15fa0 RCX: 00007f9f87b9cdd9
RDX: 0000200000000400 RSI: 00002000000003c0 RDI: 0000000002160080
RBP: 00007f9f87c32d69 R08: 0000200000000480 R09: 0000200000000480
R10: 0000200000000440 R11: 0000000000000202 R12: 0000000000000000
R13: 00007f9f87e16038 R14: 00007f9f87e15fa0 R15: 00007ffff19d30e8
 </TASK>
