bisecting fixing commit since fbc5fe7a54d02e11972e3b2a5ddb6ffc88162c8f
building syzkaller on f879db37f90dcefb681897d2e486c11d8298cb72
testing commit fbc5fe7a54d02e11972e3b2a5ddb6ffc88162c8f with gcc (GCC) 8.1.0
kernel signature: 2adf0250f1ee8804cc38e94000a4646326d4c337
all runs: crashed: WARNING in task_participate_group_stop
testing current HEAD 4c5bf01e16a7ec59e59a38a61f793c5d1d5560c7
testing commit 4c5bf01e16a7ec59e59a38a61f793c5d1d5560c7 with gcc (GCC) 8.1.0
kernel signature: 0d27d311516ad1ae8c0dd6aa13988c60b1ec49d8
all runs: crashed: WARNING in task_participate_group_stop
revisions tested: 2, total time: 23m55.204613907s (build: 16m58.232205006s, test: 6m18.436959366s)
the crash still happens on HEAD
commit msg: Linux 4.14.161
crash: WARNING in task_participate_group_stop
bridge0: port 2(bridge_slave_1) entered forwarding state
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
------------[ cut here ]------------
IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready
WARNING: CPU: 0 PID: 6824 at kernel/signal.c:353 task_participate_group_stop+0x192/0x1f0 kernel/signal.c:346
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 6824 Comm: 3 Not tainted 4.14.161-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:task_participate_group_stop+0x192/0x1f0 kernel/signal.c:353
RSP: 0018:ffff88809887fba8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff88809b66ed98 RCX: 1ffff11012ed2564
RDX: 1ffff110136cddb3 RSI: 0000000000000016 RDI: ffff888097692280
RBP: ffff88809887fbc8 R08: ffff888097692b20 R09: 0000000000005aab
R10: 0000000000000000 R11: ffff888097692280 R12: ffff88809b66ed00
R13: 0000000000040000 R14: ffff88809887ff58 R15: dffffc0000000000
 do_signal_stop+0x186/0x690 kernel/signal.c:2102
 get_signal+0xb74/0x1b30 kernel/signal.c:2288
 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 arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x416/0x5b0 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x324
RSP: 002b:00007ffcd4e5c050 EFLAGS: 00000200 ORIG_RAX: 000000000000003b
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..