[syzbot] [nilfs?] WARNING in nilfs_rmdir (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e3c33bc767b5 Merge tag 'mm-hotfixes-stable-2026-03-23-17-5..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1327aa06580000
kernel config: https://syzkaller.appspot.com/x/.config?x=45cb3c58fd963c27
dashboard link: https://syzkaller.appspot.com/bug?extid=b41999640fad20a4dd44
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/95a5c5b7cf3f/disk-e3c33bc7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9813b6b6d1c8/vmlinux-e3c33bc7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/711f8da725b2/bzImage-e3c33bc7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b41999...@syzkaller.appspotmail.com

NILFS (loop2): nilfs_palloc_commit_free_entry (ino=6): entry number 14 already freed
------------[ cut here ]------------
inode->i_nlink == 0
WARNING: fs/inode.c:418 at drop_nlink+0xc5/0x110 fs/inode.c:418, CPU#0: syz-executor/12719
Modules linked in:
CPU: 0 UID: 0 PID: 12719 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:drop_nlink+0xc5/0x110 fs/inode.c:418
Code: c0 08 00 00 be 08 00 00 00 e8 e7 e1 ea ff f0 48 ff 83 c0 08 00 00 5b 41 5c 41 5e 41 5f 5d e9 c2 5b e7 08 cc e8 6c c1 84 ff 90 <0f> 0b 90 eb 81 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 5b ff ff ff
RSP: 0018:ffffc90005b6fc50 EFLAGS: 00010293
RAX: ffffffff823fb6e4 RBX: ffff888062dfd2a8 RCX: ffff888040885b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100573ed19 R12: 1ffff1100c5bfa5e
R13: ffff888062dfd2a8 R14: ffff888062dfd2f0 R15: dffffc0000000000
FS: 000055557bc92500(0000) GS:ffff888126339000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f323ffc CR3: 00000000533a4000 CR4: 00000000003526f0
Call Trace:
<TASK>
nilfs_rmdir+0x1b4/0x250 fs/nilfs2/namei.c:347
vfs_rmdir+0x400/0x6f0 fs/namei.c:5338
filename_rmdir+0x292/0x520 fs/namei.c:5393
__do_sys_unlinkat fs/namei.c:5568 [inline]
__se_sys_unlinkat+0x71/0x1a0 fs/namei.c:5561
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3a7afeb8b7
Code: 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 b8 07 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdf64d6368 EFLAGS: 00000207 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 00007f3a7afeb8b7
RDX: 0000000000000200 RSI: 00007ffdf64d7510 RDI: 00000000ffffff9c
RBP: 00007f3a7b082050 R08: 0000000000008560 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000207 R12: 00007ffdf64d7510
R13: 00007f3a7b082050 R14: 0000000000085d50 R15: 00007ffdf64d96d0
</TASK>


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