Message-ID: <2219ec0f-edc4-4267-b251-ee060fd951e2@kernel.org>
Date: Thu, 15 Jan 2026 21:05:35 +0100
From: "David Hildenbrand (Red Hat)" <david@...nel.org>
To: kalyazin@...zon.com, Matthew Wilcox <willy@...radead.org>,
 "Kalyazin, Nikita" <kalyazin@...zon.co.uk>
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Subject: Re: [PATCH v9 01/13] set_memory: add folio_{zap, restore}_direct_map
 helpers

On 1/15/26 18:45, Nikita Kalyazin wrote:
> 
> 
> On 15/01/2026 15:55, Matthew Wilcox wrote:
>> On Wed, Jan 14, 2026 at 01:45:23PM +0000, Kalyazin, Nikita wrote:
>>> +int folio_zap_direct_map(struct folio *folio)
>>> +{
>>> +     return set_direct_map_valid_noflush(folio_page(folio, 0),
>>> +                                         folio_nr_pages(folio), false);
>>> +}
>>
>> The implementation isn't the greatest.  None of the implementations
>> of set_direct_map_valid_noflush() actually do anything with the struct
>> page; they all call page_address() or page_to_virt() (fundamentally the
>> same thing).  So converting folio->page->address is a bit inefficient.
>>
>> It feels like we should change set_direct_map_valid_noflush() to take a
>> const void * and pass either page_address() or folio_address(), depending
>> whether the caller has a page or a folio.  What do you think?
> 
> I have nothing against that.  execmem_set_direct_map_valid() appears to
> be the only other user of set_direct_map_valid_noflush() so it isn't
> going to be a broad change.

Makes perfect sense to me :)

-- 
Cheers

David

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