------------[ cut here ]------------
!valid_signal(sig)
WARNING: kernel/signal.c:2174 at do_notify_parent+0xd18/0xe30, CPU#0: syz.6.2176/17469
Modules linked in:
CPU: 0 UID: 0 PID: 17469 Comm: syz.6.2176 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 60 18 90 0e 01 48 c7 c7 e0 3a cb 8b be a3 08 00 00 48 c7 c2 60 3c cb 8b e8 63 8d 17 00 e9 2e fa ff ff e8 a9 53 3b 00 90 <0f> 0b 90 45 31 e4 e9 1c ff ff ff e8 98 53 3b 00 90 0f 0b 90 e9 db
RSP: 0018:ffffc90006bcf9e0 EFLAGS: 00010093
RAX: ffffffff818a6bc7 RBX: dffffc0000000000 RCX: ffff8881b7c3bb00
RDX: 0000000000000000 RSI: 0000000000000091 RDI: 0000000000000040
RBP: ffffc90006bcfb30 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000d79f58 R12: ffff88816fdb3c10
R13: ffff8881b7c3bb00 R14: 0000000000000091 R15: 1ffff92000d79f44
FS:  00007fd5b51bd6c0(0000) GS:ffff88818dc90000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8240c0d000 CR3: 000000011b320000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 do_exit+0x13f1/0x22c0
 do_group_exit+0x21b/0x2d0
 get_signal+0x1284/0x1330
 arch_do_signal_or_restart+0xbc/0x830
 irqentry_exit+0x284/0x730
 asm_exc_page_fault+0x26/0x30
RIP: 0033:0x7fd5b439cde1
Code: Unable to access opcode bytes at 0x7fd5b439cdb7.
RSP: 002b:fffffffffffffd30 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007fd5b4616090 RCX: 00007fd5b439cdd9
RDX: 0000000000000000 RSI: fffffffffffffd30 RDI: 0000000041840491
RBP: 00007fd5b4432d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007fd5b4616128 R14: 00007fd5b4616090 R15: 00007ffe45238808
 </TASK>
