Re: [PATCH v5] eventfs: Remove eventfs_file and just use eventfs_inode

[Heiko Carstens <hca@linux.ibm.com>]

On Fri, Nov 17, 2023 at 03:23:35PM +0100, Heiko Carstens wrote:
> I think this patch causes from time to time crashes when running ftrace
> selftests. In particular I guess there is a bug wrt error handling in this
> function (see below for call trace):
> 
> > +static struct dentry *
> > +create_file_dentry(struct eventfs_inode *ei, struct dentry **e_dentry,
> > +		   struct dentry *parent, const char *name, umode_t mode, void *data,
> > +		   const struct file_operations *fops, bool lookup)
> > +{
...
> Note that the compare and swap instruction within d_invalidate() generates
> a specification exception because it operates on an invalid address
> (0xffffffffffffffef), which happens to be -EEXIST. So my assumption is that
> create_dir_dentry() has incorrect error handling and passes -EEXIST instead
> of a valid dentry pointer to d_invalidate().
> 
> But I leave it up to you to figure this out :)

Ok, wrong function quoted of course. But the rest of my statement
should be correct.