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

[David Hildenbrand <david@redhat.com>]

>>> 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