On Tue, Aug 13, 2024 at 3:02 PM Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> On Tue, 2024-08-13 at 14:30 +0200, Christian Brauner wrote:
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index fd34b5755c0b..319c566a9e98 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -947,6 +947,7 @@ static inline unsigned imajor(const struct inode *inode)
> > }
> >
> > struct fown_struct {
> > + struct file *file; /* backpointer for security modules */
>
> This struct was 32 bytes before (on x86_64). Now it'll be 40. That's
> fine, but it may be worthwhile to create a dedicated slabcache for this
> now, since it's no longer a power-of-2 size.
>
creating a dedicated slab would be a waste imo
If someone is concerned with memory usage here, I note that plausibly
the file pointer can be plumbed through sigio code, eliding any use of
the newly added ->file
However, a real daredevil would check if the thing to do is perhaps to
add a 48-byte malloc slab. But that would require quite a bit of
looking at allocations elsewhere, collecting stats and whatnot. Noting
this just in case, I have negative interest in looking at this.
--
Mateusz Guzik <mjguzik gmail.com>
