Re: [syzbot] WARNING in kernfs_active

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    61c3426aca2c Add linux-next specific files for 20221102
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12c40689880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=acb529cc910d907c
dashboard link: https://syzkaller.appspot.com/bug?extid=590ce62b128e79cf0a35
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1457cdda880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=179969da880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cc56d88dd6a3/disk-61c3426a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5921b65b080f/vmlinux-61c3426a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/39cbd355fedd/bzImage-61c3426a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+590ce62b128e79cf0a35@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
WARNING: CPU: 1 PID: 5234 at fs/kernfs/dir.c:36 kernfs_active+0x119/0x150 fs/kernfs/dir.c:36
Modules linked in:
CPU: 1 PID: 5234 Comm: syz-executor157 Not tainted 6.1.0-rc3-next-20221102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
RIP: 0010:kernfs_active+0x119/0x150 fs/kernfs/dir.c:36
Code: e8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 1f 8b 5b 04 31 ff 89 de e8 06 9a 7e ff 89 d8 5b f7 d0 5d c1 e8 1f c3 e8 27 9d 7e ff <0f> 0b eb a5 48 89 ef e8 eb 2a cb ff eb d7 48 c7 c7 2c 1a e3 8d e8
RSP: 0018:ffffc90003cdfbc0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8881400f31d0 RCX: 0000000000000000
RDX: ffff88802707d7c0 RSI: ffffffff81fe4429 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8881400f31d0
R13: ffff88802a48e000 R14: 0000000000000000 R15: 0000000000000001
FS:  0000555555ffe300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005f6b40 CR3: 000000007edff000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kernfs_find_and_get_node_by_id+0x84/0x170 fs/kernfs/dir.c:708
 __kernfs_fh_to_dentry+0xdb/0x270 fs/kernfs/mount.c:102
 exportfs_decode_fh_raw+0x127/0x7b0 fs/exportfs/expfs.c:435
 exportfs_decode_fh+0x38/0x90 fs/exportfs/expfs.c:575
 do_handle_to_path fs/fhandle.c:152 [inline]
 handle_to_path fs/fhandle.c:207 [inline]
 do_handle_open+0x2b6/0x8b0 fs/fhandle.c:223
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f51080a6ba9
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcd1c41c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000130
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f51080a6ba9
RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000005
RBP: 00007f510806ad50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f510806ade0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>