bisecting fixing commit since a41ba30d9df20fe141c92aacbb56b6b077f19716
building syzkaller on 4afdfa205b55633e7eb9db03a9d099d7aa324801
testing commit a41ba30d9df20fe141c92aacbb56b6b077f19716 with gcc (GCC) 8.1.0
kernel signature: 8abaed13026d7d1ce5180555deee840b3f2ec35137678b4a8ad1b2dfaa30cd40
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 inc_nlink
run #5: crashed: WARNING in inc_nlink
run #6: crashed: WARNING in corrupted
run #7: crashed: WARNING in inc_nlink
run #8: crashed: WARNING in inc_nlink
run #9: crashed: WARNING in inc_nlink
testing current HEAD 14b58326976de6ef3998eefec1dd7f8b38b97a75
testing commit 14b58326976de6ef3998eefec1dd7f8b38b97a75 with gcc (GCC) 8.1.0
kernel signature: 2cf0634cd09625e2f3eddc1336dbf780b90ef53fb239804fd8066efb8d06b6bf
all runs: crashed: WARNING in inc_nlink
revisions tested: 2, total time: 26m12.241456128s (build: 18m48.711139486s, test: 5m56.321774744s)
the crash still happens on HEAD
commit msg: Linux 4.14.193
crash: WARNING in inc_nlink
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
MINIX-fs: mounting unchecked file system, running fsck is recommended
------------[ cut here ]------------
WARNING: CPU: 1 PID: 7770 at fs/inode.c:342 inc_nlink+0x10c/0x130 fs/inode.c:341
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 7770 Comm: syz-executor.3 Not tainted 4.14.193-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+0x14b/0x1f1 lib/dump_stack.c:58
 panic+0x1b0/0x358 kernel/panic.c:183
 __warn.cold.7+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:964
RIP: 0010:inc_nlink+0x10c/0x130 fs/inode.c:342
RSP: 0018:ffff888085267d30 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88807e5e7970 RCX: ffff88807e5e7990
RDX: 1ffff1100fcbcf49 RSI: ffff888082413c60 RDI: ffff88807e5e7a48
RBP: ffff888085267d48 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88807e5e79b8
R13: ffff88807e5e7970 R14: ffff888082413c60 R15: ffff888082413cb8
 inode_inc_link_count include/linux/fs.h:2035 [inline]
 minix_mkdir+0x64/0x150 fs/minix/namei.c:121
 vfs_mkdir+0x37f/0x620 fs/namei.c:3849
 SYSC_mkdirat fs/namei.c:3872 [inline]
 SyS_mkdirat+0x1ad/0x210 fs/namei.c:3856
 SYSC_mkdir fs/namei.c:3883 [inline]
 SyS_mkdir+0x14/0x20 fs/namei.c:3881
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45caa9
RSP: 002b:00007fc21ceebc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00000000004f5bc0 RCX: 000000000045caa9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000240
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000734 R14: 00000000004c2580 R15: 00007fc21ceec6d4
Kernel Offset: disabled
Rebooting in 86400 seconds..