bisecting fixing commit since a5758c5311775625be7f6dd54757ed356dbf2977
building syzkaller on 34bf9440bd06034f86b5d9ac8afbf078129cbdae
testing commit a5758c5311775625be7f6dd54757ed356dbf2977 with gcc (GCC) 8.1.0
kernel signature: 547d1be77753fab7377fa4b38b4cc6cb143428b8
all runs: crashed: WARNING in get_signal
testing current HEAD a844dc4c544291470aa69edbe2434b040794e269
testing commit a844dc4c544291470aa69edbe2434b040794e269 with gcc (GCC) 8.1.0
kernel signature: 11d82006496c83d81201c72f3c23ed856737f046
all runs: crashed: WARNING in get_signal
revisions tested: 2, total time: 23m31.252033575s (build: 16m31.260980995s, test: 6m22.344762674s)
the crash still happens on HEAD
commit msg: Linux 4.14.158
crash: WARNING in get_signal
IPv6: ADDRCONF(NETDEV_UP): bridge_slave_0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready
------------[ cut here ]------------
IPv6: ADDRCONF(NETDEV_CHANGE): bridge_slave_0: link becomes ready
WARNING: CPU: 1 PID: 6852 at kernel/signal.c:2160 get_signal+0x14c0/0x1b30 include/linux/freezer.h:60
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 6852 Comm: syz-executor.2 Not tainted 4.14.158-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xf7/0x13b lib/dump_stack.c:58
 panic+0x1b0/0x358 kernel/panic.c:183
 __warn.cold.8+0x25/0x2c kernel/panic.c:547
 report_bug+0x1a4/0x1f3 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 do_error_trap+0x1bd/0x310 arch/x86/kernel/traps.c:295
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:963
RIP: 0010:do_jobctl_trap kernel/signal.c:2160 [inline]
RIP: 0010:get_signal+0x14c0/0x1b30 kernel/signal.c:2292
RSP: 0018:ffff88808b8efc50 EFLAGS: 00010046
RAX: 00000001ffffffff RBX: ffff88808b150000 RCX: 1ffff1101263cd54
RDX: 1ffff1101380c643 RSI: 0000000000008000 RDI: ffff88808b150098
RBP: ffff88808b8efd00 R08: ffff8880931e6aa0 R09: 0000000000006e8c
R10: 0000000000000000 R11: ffff8880931e6200 R12: 0000000000000000
R13: ffff8880931e6200 R14: ffff88808b8eff58 R15: dffffc0000000000
 do_signal+0x7f/0x19a0 arch/x86/kernel/signal.c:814
 exit_to_usermode_loop+0x114/0x1b0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath+0x232/0x2b0 arch/x86/entry/common.c:270
 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:397
RIP: 0033:0x4592c9
bridge0: port 1(bridge_slave_0) entered blocking state
RSP: 002b:00007f066575fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00000000004592c9
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 000000000a01ffff
RBP: 000000000075bf20 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f06657606d4
R13: 00000000004bf72a R14: 00000000004d0e18 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..