Re: [PATCH 2/2] vmalloc: reject vmap with VM_FLUSH_RESET_PERMS

[Lorenzo Stoakes]

On Fri, Dec 23, 2022 at 03:03:12PM +0100, Christoph Hellwig wrote:
> On Fri, Dec 23, 2022 at 10:24:25AM +0000, Lorenzo Stoakes wrote:
> > Might it be worth adding a specific vmap mask that explicitly indicates what
> > flags are permissible on vmap()? Then this could become e.g.:-
> >
> > 	if (WARN_ON_ONCE(flags & ~VM_VMAP_PERMITTED_MASK))
> > 		return NULL;
> >
> > And would be self-documenting as to why we are disallowing flags (i.e. they are
> > not part of the permitted vmap mask).
>
> That's probably a good idea.  It might need some time to audit
> for use of all the flags, though.

Perhaps leave that for a later patch (I could take a look as well), but in the
meantime might be worth adding a quick comment here indicating why the flag is
prohibited?