Re: [PATCH v1] kernel/fork: only call untrack_pfn_clear() on VMAs duplicated for fork()

[David Hildenbrand]

> > > But maybe I misunderstand your approach :) Happy to obviously look and if
> > > not like some crazy thing just for PAT (you can understand why I would not
> > > like this) will be supportive :>)
> >
> > This is something quick (well, longer than I wish it would take) that seems to
> > work. There are smaller pat-internal cleanups to be had on top of this, and
> > the new functions shall be documented.
> >
> >
> > Observe how:
> > * We remove VM_PAT and that weird VM flags manipulation + "locked" flag
> > * We remove any traces of the nasty tracking handling from mremap+fork code
> > * Just like anon_vma_name, it hooks into vm_area_dup()/vm_area_free().
> > * We remove the page table lookup via get_pat_info()->... completely
> > * We remove the VMA parameter from PAT code completely
> > * We reduce the track/untrack/sanitize interface to 3 functions
>
> Yeah this is all lovely!
>
> OK this should hopefully be workable then!

Okay, let me polish that up (and see if there is any reasonable way to 
split it up), and write some doc+descriptions .. and do some more testing.

The VMA split reproducer is definitely happy with this already.

--
Cheers,

David / dhildenb