Re: [PATCH] mm/rmap: Add anon_vma lifetime debug check

[David Hildenbrand]

On 25.07.25 13:24, Jann Horn wrote:
> On Fri, Jul 25, 2025 at 1:12 PM David Hildenbrand <david@xxxxxxxxxx> wrote:
> > On 25.07.25 13:08, Jann Horn wrote:
> > > On Thu, Jul 24, 2025 at 11:56 PM David Hildenbrand <david@xxxxxxxxxx> wrote:
> > > > 2) We have a folio here, so ... better
> > > >
> > > > if (folio_test_anon(folio) && !folio_test_ksm(folio)) {
> > > >           ...
> > > > }
> > >
> > > Hrm, okay. It kind of irks me to write it as two checks when really I
> > > want to ask "is it this one specific type", but yeah, will change it.
> >
> > Well, ksm is a subtype of anon.
>
> I mean... not really? At least ksm folios are not a subtype of normal
> anon folios. 

Well, what I mean is:

A KSM folio is considered an anon folio.

An anon folio is not necessarily a KSM folio.

Of course, there are implementation differences when it comes to 
folio->mapping etc, just the way the rmap works.

--
Cheers,

David / dhildenb