bisecting fixing commit since 9b15f7fae677336e04b9e026ff91854e43165455
building syzkaller on 1ce142dcc7e25341405592c66bcb7cb0d60d2b3a
testing commit 9b15f7fae677336e04b9e026ff91854e43165455 with gcc (GCC) 8.1.0
kernel signature: 8a34859b9a3fbf4a3403b14bf6ab154d8705a0aa2f596efb3fbe017b0324b6a1
all runs: crashed: WARNING in get_signal
testing current HEAD 3fc898571b974f9a05e4e5c1fe17b18548207091
testing commit 3fc898571b974f9a05e4e5c1fe17b18548207091 with gcc (GCC) 8.1.0
kernel signature: 190d61f49a70256cf3adda4f6302c815eb478ec1181a839dfe30788c10537d0e
all runs: crashed: WARNING in get_signal
revisions tested: 2, total time: 25m0.695081334s (build: 17m47.486211481s, test: 6m38.547246763s)
the crash still happens on HEAD
commit msg: Linux 4.19.128
crash: WARNING in get_signal
IPv6: ADDRCONF(NETDEV_UP): veth0_macvtap: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): macsec0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready
WARNING: CPU: 0 PID: 7828 at kernel/signal.c:2334 get_signal+0x13c9/0x1a00 include/linux/freezer.h:60
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7828 Comm: syz-executor.0 Not tainted 4.19.128-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x123/0x177 lib/dump_stack.c:118
 panic+0x1cd/0x375 kernel/panic.c:186
 __warn.cold.8+0x1b/0x3e kernel/panic.c:541
 report_bug+0x1a4/0x200 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x200/0x350 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:do_jobctl_trap kernel/signal.c:2334 [inline]
RIP: 0010:get_signal+0x13c9/0x1a00 kernel/signal.c:2467
Code: 31 db eb e1 48 89 df e8 d5 2c 16 00 84 c0 0f 84 c7 ed ff ff 31 ff e8 b6 2d 16 00 e9 bb ed ff ff 41 89 c4 31 db e9 74 ff ff ff <0f> 0b be 00 80 00 00 e9 a9 f9 ff ff e8 f6 05 15 00 84 c0 0f 85 15
RSP: 0018:ffff88808cc77c60 EFLAGS: 00010046
RAX: 00000001ffffffff RBX: ffff88808cc77dd8 RCX: ffffffff814bdf90
RDX: 1ffff110151dcb73 RSI: 0000000000008000 RDI: ffff88808ce27320
RBP: ffff88808cc77d10 R08: ffffed10151dcb72 R09: ffffed10151dcb71
R10: ffffed10151dcb71 R11: ffff8880a8ee5b8b R12: ffff88808ce27280
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff88808f7f2680
 do_signal+0x87/0x1960 arch/x86/kernel/signal.c:821
 exit_to_usermode_loop+0x114/0x200 arch/x86/entry/common.c:163
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath+0x31a/0x3b0 arch/x86/entry/common.c:271
 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:407
RIP: 0033:0x45c6b9
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7d88a39c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: 0000000000000000 RBX: 00007f7d88a3a6d4 RCX: 000000000045c6b9
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 000000000a01ffff
RBP: 000000000076bf20 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000074 R14: 00000000004c2f79 R15: 000000000076bf2c
Kernel Offset: disabled
Rebooting in 86400 seconds..