Re: [PATCH] mm: don't ioremap COWed anon pages in generic_access_phys()

[Lorenzo Stoakes (ARM)]

On Fri, Oct 02, 2026 at 12:04:27PM +0200, David Hildenbrand (Arm) wrote:
> On 10/2/26 12:02, David Hildenbrand (Arm) wrote:
> > On 10/2/26 10:38, Lorenzo Stoakes (ARM) wrote:
> >> On Thu, Oct 01, 2026 at 10:22:29PM +0200, David Hildenbrand (Arm) wrote:
> >>>
> >>
> >> Sorry to say this looks schlopped.
> >>
> >> This guy has sent 10 series across 6 subsystems over ~21 hrs:
> >>
> >> https://lore.kernel.org/all/?q=f%3Angocthang2710.1999%40gmail.com
> >>
> >> Nguyen - please do not flood the kernel with patches, and please use the
> >> Assisted-by tag for generated content.
> >>
> >> The original code you submitted is really not great even if the issue may
> >> be valid.
> >>
> >> So I'd say somebody from the core team should take over this if we want to
> >> come up with a patch.
> >
> > Yes, I'll take care of it.
> >
> > [...]
> >>>
> >>> Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> >>
> >> This looks reasonable but I hate that we have 'special' CoW overrides like
> >> this :)
> >
> > After sending this yesterday, I concluded that we can do this cleaner: just have
> >
> > bool normal_page;
> >
> > (naming suggestions?)
> >
> > that express that this is something refcounted with a struct page, like
> > documented for vm_normal_page().
>
> Hmm, have to think about that once more, regarding VM_IO and if there are some
> cases that would actually have to work in generic_access_phys().

Well, my series at least makes it easier to reason about VMA_IO_BIT!

Though not sure if it really touches PFN map cases specifically.

>
> --
> Cheers,
>
> David

--
Cheers, Lorenzo