bisecting fixing commit since dda0e2920330128e0dbdeb11c8f25031aa40b11c
building syzkaller on ef26b61025bac4c6bb1a0ef7eccc45f43f84c841
testing commit dda0e2920330128e0dbdeb11c8f25031aa40b11c with gcc (GCC) 8.1.0
kernel signature: 3f8d064fb1e69aa63af7c0c56ac0b141e63c37728098a2f03e82fef69731ce94
run #0: crashed: WARNING in inc_nlink
run #1: crashed: WARNING in inc_nlink
run #2: crashed: WARNING in inc_nlink
run #3: crashed: WARNING in inc_nlink
run #4: crashed: WARNING in corrupted
run #5: crashed: WARNING in inc_nlink
run #6: crashed: WARNING in inc_nlink
run #7: crashed: WARNING in inc_nlink
run #8: crashed: WARNING in inc_nlink
run #9: crashed: WARNING in inc_nlink
testing current HEAD fdc072324f3c66190a20f57490b4842a391d8233
testing commit fdc072324f3c66190a20f57490b4842a391d8233 with gcc (GCC) 8.1.0
kernel signature: 0662704d009dec5f1251ce72617a67fd21f3591444b65309da0a11925dcae09d
all runs: crashed: WARNING in inc_nlink
revisions tested: 2, total time: 26m22.540531426s (build: 18m49.682184672s, test: 6m24.332192813s)
the crash still happens on HEAD
commit msg: Linux 4.19.120
crash: WARNING in inc_nlink
MINIX-fs: mounting unchecked file system, running fsck is recommended
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:3e) already exists on: batadv_slave_1
------------[ cut here ]------------
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
WARNING: CPU: 1 PID: 7830 at fs/inode.c:343 inc_nlink.cold.28+0xc/0x13 fs/inode.c:343
Kernel panic - not syncing: panic_on_warn set ...

IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
CPU: 1 PID: 7830 Comm: syz-executor.4 Not tainted 4.19.120-syzkaller #0
batman_adv: batadv0: Interface activated: batadv_slave_1
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:1037
RIP: 0010:inc_nlink.cold.28+0xc/0x13 fs/inode.c:343
Code: 10 75 08 48 89 df e8 2a b5 ff ff 5b 41 5c 5d c3 e8 90 60 f1 ff eb e2 e8 a9 60 f1 ff eb ac 48 c7 c7 40 b3 33 87 e8 1a e6 ad ff <0f> 0b e9 22 96 ff ff 48 8d 7b 40 b8 ff ff 37 00 48 89 fa 48 c1 e0
RSP: 0018:ffff88808b6bfd38 EFLAGS: 00010282
RAX: 0000000000000024 RBX: ffff88808116b960 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff87677900 RDI: ffffffff8a183960
RBP: ffff88808b6bfd58 R08: ffffed1015d65079 R09: ffffed1015d65078
R10: ffffed1015d65078 R11: ffff8880aeb283c7 R12: ffff88808116b9a8
R13: 1ffff110116d7fad R14: ffff888082cfd300 R15: ffff888082cfd358
 inode_inc_link_count include/linux/fs.h:2098 [inline]
 minix_mkdir+0x68/0x160 fs/minix/namei.c:117
 vfs_mkdir+0x37f/0x620 fs/namei.c:3819
 do_mkdirat+0x1c2/0x220 fs/namei.c:3842
 __do_sys_mkdirat fs/namei.c:3853 [inline]
 __se_sys_mkdirat fs/namei.c:3851 [inline]
 __x64_sys_mkdirat+0x71/0xb0 fs/namei.c:3851
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c879
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:00007f13498b2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f13498b36d4 RCX: 000000000045c879
RDX: 00000000000001ff RSI: 0000000020000080 RDI: 0000000000000003
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000072e R14: 00000000004c9f33 R15: 000000000076bf0c
Kernel Offset: disabled
Rebooting in 86400 seconds..