Re: [PATCH 2/2] mm/thp: Rename pmd_mknotpresent() as pmd_mknotvalid()

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On 04/21/2020 02:33 AM, Will Deacon wrote:
> On Fri, Mar 20, 2020 at 10:24:17AM +0530, Anshuman Khandual wrote:
>> pmd_present() is expected to test positive after pmdp_mknotpresent() as the
>> PMD entry still points to a valid huge page in memory. pmdp_mknotpresent()
>> implies that given PMD entry is just invalidated from MMU perspective while
>> still holding on to pmd_page() referred valid huge page thus also clearing
>> pmd_present() test. This creates the following situation which is counter
>> intuitive.
>>
>> [pmd_present(pmd_mknotpresent(pmd)) = true]
>>
>> This renames pmd_mknotpresent() as pmd_mknotvalid() reflecting the helper's
>> functionality more accurately while changing the above mentioned situation
>> as follows. This does not create any functional change.
>>
>> [pmd_present(pmd_mknotvalid(pmd)) = true]
>>
>> This is not applicable for platforms that define own pmdp_invalidate() via
>> __HAVE_ARCH_PMDP_INVALIDATE. Suggestion for renaming came during a previous
>> discussion here.
> 
> Bikeshed alert: maybe pmd_mkinvalid() would be better, given that this is
> a one-trick pony for pmdp_invalidate()?

I had thought about making it pmd_mkinvalid() earlier. But as we were replacing
pmd_mknotpresent(), hence went with similar pattern pmd_mknotvalid() which was
originally suggested by Catalin. There is an existing pte_mknotpresent() in arc
platform as well. I dont have a very strong opinion either way, will be happy
to rename. But then still wondering if we really need to.

> 
> Will
> 




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