Re: [PATCH v2 4/4] mm: page_table_check: Ensure user pages are not slab pages

[Pasha Tatashin]

> >> Acked-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> >>
> >> I would also update order in mm/memory.c
> >> static int validate_page_before_insert(struct page *page)
> >> {
> >> if (PageAnon(page) || PageSlab(page) || page_has_type(page))
> >>
> >> It is not strictly a bug there, as it works by accident, but
> >> PageSlab() should go before PageAnon(), because without checking if
> >> this is PageSlab() we should not be testing for PageAnon().
> >
> > Right. Perhaps it would be better to send another patch for this
> > separately.

Yes, as a separate from this series patch would work.

>
> Probably not really worth it IMHO. With PageSlab() we might have
> PageAnon() false-positives. Either will take the same path here ...

That is correct, it works by accident, but it is not a good idea to
keep a broken logic at least because it may be copied into other
places.