Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO)

Tycho Andersen
2017-09-11T15:03:46Z

On Sat, Sep 09, 2017 at 08:35:17AM -0700, Laura Abbott wrote:
> On 09/07/2017 10:36 AM, Tycho Andersen wrote:
> > +static inline struct xpfo *lookup_xpfo(struct page *page)
> > +{
> > + struct page_ext *page_ext = lookup_page_ext(page);
> > +
> > + if (unlikely(!page_ext)) {
> > + WARN(1, "xpfo: failed to get page ext");
> > + return NULL;
> > + }
> > +
> > + return (void *)page_ext + page_xpfo_ops.offset;
> > +}
> > +
>
> Just drop the WARN. On my arm64 UEFI machine this spews warnings
> under most normal operation. This should be normal for some
> situations but I haven't had the time to dig into why this
> is so pronounced on arm64.

Will do, thanks! If you figure out under what conditions it's normal,
I'd be curious :)

Tycho