bisecting fixing commit since b172b44fcb1771e083aad806fa96f3f60e2ddfac
building syzkaller on 07e953c105af057cb474bc086f68fb7ec5b241ec
testing commit b172b44fcb1771e083aad806fa96f3f60e2ddfac
compiler: gcc version 8.4.1 20210217 (GCC)
kernel signature: 57db8bdc116384d655d08d700631a8135c8f720fe5d1b2fe44b79248b83a9491
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
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 inc_nlink
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 corrupted
testing current HEAD 3f8a27f9e27bd78604c0709224cec0ec85a8b106
testing commit 3f8a27f9e27bd78604c0709224cec0ec85a8b106
compiler: gcc version 8.4.1 20210217 (GCC)
kernel signature: 0651e9cff080c1706ee172d1041f836a84966a5e917f08ae5eef9bd2e86283fa
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 corrupted
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: 22m49.731126737s (build: 15m51.085572012s, test: 6m25.332553527s)
the crash still happens on HEAD
commit msg: Linux 4.19.211
crash: WARNING in inc_nlink
IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
------------[ cut here ]------------
WARNING: CPU: 0 PID: 9867 at fs/inode.c:343 inc_nlink.cold.15+0xc/0x13 fs/inode.c:343
IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 9867 Comm: syz-executor.0 Not tainted 4.19.211-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: a2 03 ff ff 0f 0b e9 70 a4 16 fa 48 c7 c7 20 8c 13 88 e8 8f 03 ff ff 0f 0b e9 ad a4 16 fa 48 c7 c7 40 94 13 88 e8 7c 03 ff ff <0f> 0b e9 33 be 16 fa 48 8d 7b 40 b8 ff ff 37 00 48 89 fa 48 c1 e0
RSP: 0018:ffff88809b6efbc8 EFLAGS: 00010282
RAX: 0000000000000024 RBX: ffff888080dce600 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff885024a0 RDI: ffffffff8bada720
RBP: ffff88809b6efbe8 R08: ffffed1017444ea9 R09: ffffed1017444ea8
R10: ffffed1017444ea8 R11: ffff8880ba227547 R12: ffff888080dce648
R13: 1ffff110136ddf82 R14: ffff8880ad83a000 R15: 0000000000000005
 fuse_link+0x34d/0x4c0 fs/fuse/dir.c:849
 vfs_link+0x640/0xa10 fs/namei.c:4243
 do_linkat+0x415/0x6b0 fs/namei.c:4311
 __do_sys_link fs/namei.c:4340 [inline]
 __se_sys_link fs/namei.c:4338 [inline]
 __x64_sys_link+0x59/0x80 fs/namei.c:4338
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4665f9
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:00007f069f8c7188 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665f9
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000020000040
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffc5472fb7f R14: 00007f069f8c7300 R15: 0000000000022000
Kernel Offset: disabled
Rebooting in 86400 seconds..