bisecting fixing commit since 1bab61d3e8cd96f2badf515dcb06e4e1029bc017
building syzkaller on 4afdfa205b55633e7eb9db03a9d099d7aa324801
testing commit 1bab61d3e8cd96f2badf515dcb06e4e1029bc017 with gcc (GCC) 8.1.0
kernel signature: 31ceb0eb6b46c723f52bc72fda06408885521a4fa8d27e5b09a121cfe1fc6d24
all runs: crashed: WARNING in inc_nlink
testing current HEAD 3fc898571b974f9a05e4e5c1fe17b18548207091
testing commit 3fc898571b974f9a05e4e5c1fe17b18548207091 with gcc (GCC) 8.1.0
kernel signature: 4fbdfdc901c4ddf57385b444600fd42adb1a868ff3cf4532e97504c6236ff17c
run #0: crashed: WARNING in inc_nlink
run #1: crashed: WARNING in corrupted
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
revisions tested: 2, total time: 24m57.739146233s (build: 17m49.089695595s, test: 6m4.391500009s)
the crash still happens on HEAD
commit msg: Linux 4.19.128
crash: WARNING in inc_nlink
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
MINIX-fs: mounting unchecked file system, running fsck is recommended
MINIX-fs: mounting unchecked file system, running fsck is recommended
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7877 at fs/inode.c:343 inc_nlink.cold.15+0xc/0x13 fs/inode.c:343
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7877 Comm: syz-executor.2 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+0x17c/0x22a lib/dump_stack.c:118
 panic+0x1cd/0x375 kernel/panic.c:186
 __warn.cold.7+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:inc_nlink.cold.15+0xc/0x13 fs/inode.c:343
Code: 10 75 08 48 89 df e8 3a c9 ff ff 5b 41 5c 5d c3 e8 d0 e5 f0 ff eb e2 e8 e9 e5 f0 ff eb ac 48 c7 c7 00 ad 33 87 e8 ea 06 ae ff <0f> 0b e9 f2 96 ff ff 48 8d 7b 40 b8 ff ff 37 00 48 89 fa 48 c1 e0
RSP: 0018:ffff88808c027d40 EFLAGS: 00010286
RAX: 0000000000000024 RBX: ffff888075c0e960 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff87676320 RDI: ffffffff8a192a60
RBP: ffff88808c027d60 R08: ffffed1015d45081 R09: ffffed1015d45080
R10: ffffed1015d45080 R11: ffff8880aea28407 R12: ffff888075c0e9a8
R13: 1ffff11011804fae R14: ffff888083245600 R15: ffff888083245658
 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_mkdir fs/namei.c:3858 [inline]
 __se_sys_mkdir fs/namei.c:3856 [inline]
 __x64_sys_mkdir+0x57/0x80 fs/namei.c:3856
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45ca29
Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f36584c7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00000000004f5b40 RCX: 000000000045ca29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000240
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000734 R14: 00000000004c2500 R15: 00007f36584c86d4
Kernel Offset: disabled
Rebooting in 86400 seconds..