[v6.6] WARNING in f2fs_rename2

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7a137e9bfa0e Linux 6.6.127
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15ee755a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2a950bf7c0bff9f9
dashboard link: https://syzkaller.appspot.com/bug?extid=abd21c28d385a6b54352
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/04a02efb4a79/disk-7a137e9b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7b848f192f0/vmlinux-7a137e9b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/77a981f90b3d/bzImage-7a137e9b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+abd21c...@syzkaller.appspotmail.com

F2FS-fs (loop3): invalid crc value
F2FS-fs (loop3): Found nat_bits in checkpoint
F2FS-fs (loop3): Try to recover 1th superblock, ret: 0
F2FS-fs (loop3): Mounted with checkpoint version = 48b305e4
------------[ cut here ]------------
WARNING: CPU: 0 PID: 9771 at fs/inode.c:332 drop_nlink+0xbf/0x100 fs/inode.c:332
Modules linked in:
CPU: 0 PID: 9771 Comm: syz.3.1202 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:drop_nlink+0xbf/0x100 fs/inode.c:332
Code: 48 8b 1b 48 8d bb 78 07 00 00 be 08 00 00 00 e8 e7 12 ea ff f0 48 ff 83 78 07 00 00 5b 41 5c 41 5e 41 5f 5d c3 e8 61 e1 91 ff <0f> 0b eb 88 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 62 ff ff ff 4c
RSP: 0018:ffffc9000487f930 EFLAGS: 00010283
RAX: ffffffff81f533af RBX: ffff888050526c00 RCX: 0000000000080000
RDX: ffffc9000db6d000 RSI: 00000000000324b5 RDI: 00000000000324b6
RBP: 0000000000000000 R08: ffff8880505270bf R09: 1ffff1100a0a4e17
R10: dffffc0000000000 R11: ffffed100a0a4e18 R12: 1ffff1100a0a4d8b
R13: ffff888050526c00 R14: ffff888050526c58 R15: dffffc0000000000
FS: 00007f4ba983e6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4ba89e9e80 CR3: 000000005e020000 CR4: 00000000003506f0
Call Trace:
<TASK>
f2fs_i_links_write fs/f2fs/f2fs.h:3127 [inline]
f2fs_rename fs/f2fs/namei.c:1008 [inline]
f2fs_rename2+0x1633/0x2270 fs/f2fs/namei.c:1283
vfs_rename+0xba2/0xed0 fs/namei.c:4880
do_renameat2+0x8e9/0xce0 fs/namei.c:5033
__do_sys_rename fs/namei.c:5079 [inline]
__se_sys_rename fs/namei.c:5077 [inline]
__x64_sys_rename+0x86/0x90 fs/namei.c:5077
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4ba899c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4ba983e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f4ba8c15fa0 RCX: 00007f4ba899c799
RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 0000200000000040
RBP: 00007f4ba8a32bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4ba8c16038 R14: 00007f4ba8c15fa0 R15: 00007fffc1b12d48
</TASK>


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 7a137e9bfa0e Linux 6.6.127
git tree: linux-6.6.y

console output: https://syzkaller.appspot.com/x/log.txt?x=13c1755a580000

kernel config: https://syzkaller.appspot.com/x/.config?x=2a950bf7c0bff9f9
dashboard link: https://syzkaller.appspot.com/bug?extid=abd21c28d385a6b54352
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=151dbde6580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12b3c202580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/04a02efb4a79/disk-7a137e9b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7b848f192f0/vmlinux-7a137e9b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/77a981f90b3d/bzImage-7a137e9b.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/f36338813d09/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=106ccd5a580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+abd21c...@syzkaller.appspotmail.com

F2FS-fs (loop0): Wrong NAT boundary, start(2560) end(3584) blocks(0)
F2FS-fs (loop0): Can't find valid F2FS filesystem in 1th superblock
F2FS-fs (loop0): invalid crc value
F2FS-fs (loop0): Found nat_bits in checkpoint
F2FS-fs (loop0): Try to recover 1th superblock, ret: 0
F2FS-fs (loop0): Mounted with checkpoint version = 48b305e4
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5923 at fs/inode.c:332 drop_nlink+0xbf/0x100 fs/inode.c:332
Modules linked in:
CPU: 1 PID: 5923 Comm: syz.0.17 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:drop_nlink+0xbf/0x100 fs/inode.c:332
Code: 48 8b 1b 48 8d bb 78 07 00 00 be 08 00 00 00 e8 e7 12 ea ff f0 48 ff 83 78 07 00 00 5b 41 5c 41 5e 41 5f 5d c3 e8 61 e1 91 ff <0f> 0b eb 88 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 62 ff ff ff 4c

RSP: 0018:ffffc90003207930 EFLAGS: 00010293
RAX: ffffffff81f533af RBX: ffff8880600f2400 RCX: ffff88807b3c3c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff8880600f28bf R09: 1ffff1100c01e517
R10: dffffc0000000000 R11: ffffed100c01e518 R12: 1ffff1100c01e48b
R13: ffff8880600f2400 R14: ffff8880600f2458 R15: dffffc0000000000
FS: 000055556292c500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000001b34263fff CR3: 00000000776ca000 CR4: 00000000003506e0

Call Trace:
<TASK>
f2fs_i_links_write fs/f2fs/f2fs.h:3127 [inline]
f2fs_rename fs/f2fs/namei.c:1008 [inline]
f2fs_rename2+0x1633/0x2270 fs/f2fs/namei.c:1283
vfs_rename+0xba2/0xed0 fs/namei.c:4880
do_renameat2+0x8e9/0xce0 fs/namei.c:5033
__do_sys_rename fs/namei.c:5079 [inline]
__se_sys_rename fs/namei.c:5077 [inline]
__x64_sys_rename+0x86/0x90 fs/namei.c:5077
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2

RIP: 0033:0x7fa9f8f9c799

Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007fffa06a1ae8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007fa9f9215fa0 RCX: 00007fa9f8f9c799

RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 0000200000000040

RBP: 00007fa9f9032bd9 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007fa9f9215fac R14: 00007fa9f9215fa0 R15: 00007fa9f9215fa0
</TASK>


---
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