Re: [syzbot] [exfat?] [ocfs2?] kernel BUG in link_path_walk

Mateusz Guzik
2025-12-04T11:58:42Z

On Thu, Dec 4, 2025 at 12:56 PM syzbot
<syzbot+d222f4b7129379c3d5bc@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> kernel BUG in link_path_walk
>
> VFS_BUG_ON_INODE(d_can_lookup(_dentry) && !S_ISDIR(_dentry->d_inode->i_mode)) encountered for inode ffff888074eca4f8
> fs ocfs2 mode 100000 opflags 0x2 flags 0x20 state 0x0 count 2

note the patch at hand made sure to avoid transient states by taking a
lock on the dentry:
+ struct dentry *_dentry = nd->path.dentry;
+ struct inode *_inode = READ_ONCE(_dentry->d_inode);
+ if (!d_can_lookup(_dentry) || !_inode || !S_ISDIR(_inode->i_mode)) {
+ spin_lock(&_dentry->d_lock);
+ VFS_BUG_ON_INODE(d_can_lookup(_dentry) &&
!S_ISDIR(_dentry->d_inode->i_mode), _dentry->d_inode);
+ spin_unlock(&_dentry->d_lock);
+ }

So the state *is* indeed bogus and this is most likely something ocfs2-internal.

I'm buggering off this report.