Message-ID: <34b246e9-0f7a-4ed6-9e43-845c4238bf41@amazon.com>
Date: Thu, 15 Jan 2026 17:45:48 +0000
From: Nikita Kalyazin <kalyazin@...zon.com>
To: Matthew Wilcox <willy@...radead.org>, "Kalyazin, Nikita"
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Subject: Re: [PATCH v9 01/13] set_memory: add folio_{zap, restore}_direct_map
 helpers



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.

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