[v6.6] WARNING in bfs_get_block

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9760bf04666d Linux 6.6.135
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=106892d2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5b35c4db8465904
dashboard link: https://syzkaller.appspot.com/bug?extid=f719c54d9fe65474cc4d
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/a685913d05a7/disk-9760bf04.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a3c1d21d4bca/vmlinux-9760bf04.xz
kernel image: https://storage.googleapis.com/syzbot-assets/09178887ef0d/bzImage-9760bf04.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f719c5...@syzkaller.appspotmail.com

loop2: detected capacity change from 0 to 64
BFS-fs: bfs_fill_super(): loop2 is unclean, continuing
------------[ cut here ]------------
WARNING: CPU: 1 PID: 6299 at fs/buffer.c:1188 mark_buffer_dirty+0x2bb/0x4c0 fs/buffer.c:1188
Modules linked in:
CPU: 1 PID: 6299 Comm: syz.2.142 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:mark_buffer_dirty+0x2bb/0x4c0 fs/buffer.c:1188
Code: 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 9f 9a fc ff e8 5a b6 88 ff 48 89 df 5b 41 5c 41 5e 41 5f 5d e9 ea 08 e8 ff e8 45 b6 88 ff <0f> 0b e9 84 fd ff ff e8 39 b6 88 ff 0f 0b e9 b0 fd ff ff e8 2d b6
RSP: 0018:ffffc9000c1c7850 EFLAGS: 00010283
RAX: ffffffff81fe6bbb RBX: ffff888059c371d0 RCX: 0000000000080000
RDX: ffffc9000d7bc000 RSI: 0000000000010c8e RDI: 0000000000010c8f
RBP: ffff888059c35a01 R08: ffff888059c371d7 R09: 1ffff1100b386e3a
R10: dffffc0000000000 R11: ffffed100b386e3b R12: ffff88801f3c6160
R13: 0000000000000200 R14: ffff888056c3f000 R15: 000000000000000f
FS: 00007f5ca1cab6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000002000 CR3: 0000000025f06000 CR4: 00000000003506e0
Call Trace:
<TASK>
bfs_move_block fs/bfs/file.c:43 [inline]
bfs_move_blocks fs/bfs/file.c:56 [inline]
bfs_get_block+0x593/0xa50 fs/bfs/file.c:125
__block_write_begin_int+0x57f/0x1af0 fs/buffer.c:2124
__block_write_begin fs/buffer.c:2173 [inline]
block_write_begin+0x9a/0x1e0 fs/buffer.c:2234
bfs_write_begin+0x35/0xd0 fs/bfs/file.c:177
generic_perform_write+0x2fe/0x5c0 mm/filemap.c:4036
generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4157
call_write_iter include/linux/fs.h:2018 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x46c/0x990 fs/read_write.c:584
ksys_pwrite64 fs/read_write.c:699 [inline]
__do_sys_pwrite64 fs/read_write.c:709 [inline]
__se_sys_pwrite64 fs/read_write.c:706 [inline]
__x64_sys_pwrite64+0x19b/0x230 fs/read_write.c:706
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: 0033:0x7f5ca0d9cdd9
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:00007f5ca1cab028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f5ca1015fa0 RCX: 00007f5ca0d9cdd9
RDX: 000000000000fdef RSI: 0000200000000140 RDI: 0000000000000005
RBP: 00007f5ca0e32d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000e7c R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5ca1016038 R14: 00007f5ca1015fa0 R15: 00007ffe8bb59498
</TASK>


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