bisecting fixing commit since 0c88e405c97ed1828443b67891e6d4bb6e56cd4e
building syzkaller on a0092f9dfdd33924abe5cf5565e4ec4748217c7b
testing commit 0c88e405c97ed1828443b67891e6d4bb6e56cd4e
compiler: gcc version 8.4.1 20210217 (GCC)
kernel signature: ebf8646ee87ebc1d85e293a57f909c27e03667905ec3201c20ea05c2d6335ab5
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 corrupted
run #10: crashed: WARNING in inc_nlink
run #11: crashed: WARNING in inc_nlink
run #12: crashed: WARNING in inc_nlink
run #13: crashed: WARNING in corrupted
run #14: crashed: WARNING in inc_nlink
run #15: crashed: WARNING in inc_nlink
run #16: crashed: WARNING in inc_nlink
run #17: crashed: WARNING in inc_nlink
run #18: crashed: WARNING in inc_nlink
run #19: crashed: WARNING in inc_nlink
testing current HEAD 6ca2f514c57864e3085a65c5e9d2adca4144bc4c
testing commit 6ca2f514c57864e3085a65c5e9d2adca4144bc4c
compiler: gcc version 8.4.1 20210217 (GCC)
kernel signature: 9f053307003e25c5f2cc3226d7aab6d9fc914820513cafbe2f83c3c00608283d
run #0: crashed: WARNING in corrupted
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 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: 26m50.081074912s (build: 19m27.080410991s, test: 6m46.279520623s)
the crash still happens on HEAD
commit msg: Linux 4.19.201
crash: WARNING in inc_nlink
VFS: Found a V7 FS (block size = 512) on device loop2
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
------------[ cut here ]------------
WARNING: CPU: 0 PID: 9803 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: 9803 Comm: syz-executor.2 Not tainted 4.19.201-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/0x226 lib/dump_stack.c:118
 panic+0x1cd/0x375 kernel/panic.c:186
 __warn.cold.7+0x1b/0x36 kernel/panic.c:541
 report_bug+0x1a1/0x200 lib/bug.c:183
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 fixup_bug arch/x86/kernel/traps.c:173 [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: fb 03 ff ff 0f 0b e9 c0 f9 16 fa 48 c7 c7 60 8a 13 88 e8 e8 03 ff ff 0f 0b e9 fd f9 16 fa 48 c7 c7 80 92 13 88 e8 d5 03 ff ff <0f> 0b e9 83 13 17 fa 48 8d 7b 40 b8 ff ff 37 00 48 89 fa 48 c1 e0
RSP: 0018:ffff888091727d98 EFLAGS: 00010282
RAX: 0000000000000024 RBX: ffff88808116b948 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff88502180 RDI: ffffffff8bada720
RBP: ffff888091727db8 R08: ffffed1017444e99 R09: ffffed1017444e98
R10: ffffed1017444e98 R11: ffff8880ba2274c7 R12: ffff88808116b990
R13: ffff8880a21ba9a0 R14: 00000000000000a8 R15: ffff8880a21ba9f8
 inode_inc_link_count include/linux/fs.h:2101 [inline]
 sysv_mkdir+0x18/0x100 fs/sysv/namei.c:131
 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: 0033:0x465889
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc5bf738188 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 000000000055bf00 RCX: 0000000000465889
RDX: 00000000000000b8 RSI: 0000000020000040 RDI: 0000000000000005
RBP: 00000000004af68d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00
R13: 00007ffdd978f37f R14: 00007fc5bf738300 R15: 0000000000022000
Kernel Offset: disabled
Rebooting in 86400 seconds..