bisecting fixing commit since 9b15f7fae677336e04b9e026ff91854e43165455
building syzkaller on 1ce142dcc7e25341405592c66bcb7cb0d60d2b3a
testing commit 9b15f7fae677336e04b9e026ff91854e43165455 with gcc (GCC) 8.1.0
kernel signature: 7ba4912e360d55f477d567d00ed4532bbaec2cc9be9b57dca1452df48f6a60e5
all runs: crashed: WARNING in get_signal
testing current HEAD 17a87580a8856170d59aab302226811a4ae69149
testing commit 17a87580a8856170d59aab302226811a4ae69149 with gcc (GCC) 8.1.0
kernel signature: 79b22b1eeb0d4531aa64effeb8dbac3a36ad931cf358131f934517598be35ffc
all runs: crashed: WARNING in get_signal
revisions tested: 2, total time: 26m4.229199827s (build: 19m3.194455407s, test: 6m10.522758183s)
the crash still happens on HEAD
commit msg: Linux 4.19.133
crash: WARNING in get_signal
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
WARNING: CPU: 1 PID: 7837 at kernel/signal.c:2334 get_signal+0x13e4/0x1a30 include/linux/freezer.h:60
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 7837 Comm: syz-executor.5 Not tainted 4.19.133-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
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x200/0x350 arch/x86/kernel/traps.c:296
batman_adv: batadv0: Interface activated: batadv_slave_0
 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+0x13e4/0x1a30 kernel/signal.c:2467
Code: 31 db eb e1 48 89 df e8 fa 22 16 00 84 c0 0f 84 ac ed ff ff 31 ff e8 db 23 16 00 e9 a0 ed ff ff 41 89 c4 31 db e9 74 ff ff ff <0f> 0b be 00 80 00 00 e9 8e f9 ff ff e8 ab fa 14 00 84 c0 0f 85 15
RSP: 0018:ffff88809039fc60 EFLAGS: 00010046
RAX: 00000001ffffffff RBX: ffff88809039fdd8 RCX: ffffffff814c5540
RDX: 1ffff11012981a43 RSI: 0000000000008000 RDI: ffff8880900f4160
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
RBP: ffff88809039fd10 R08: ffffed1012981a42 R09: ffffed1012981a41
R10: ffffed1012981a41 R11: ffff888094c0d20b R12: ffff8880900f40c0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff888090b8c300
 do_signal+0x87/0x1960 arch/x86/kernel/signal.c:821
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
 exit_to_usermode_loop+0x114/0x200 arch/x86/entry/common.c:163
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath+0x31a/0x3b0 arch/x86/entry/common.c:271
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready
 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:407
batman_adv: batadv0: Interface activated: batadv_slave_0
RIP: 0033:0x45c739
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
Code: 2d 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 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f8417383c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: 0000000000000000 RBX: 00007f84173846d4 RCX: 000000000045c739
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 000000000a01ffff
RBP: 000000000076bf20 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000074 R14: 00000000004c2ff9 R15: 000000000076bf2c
Kernel Offset: disabled
Rebooting in 86400 seconds..