Re: [RFC PATCH] mm: only set fault addrsss' access bit in do_anonymous_page

[David Hildenbrand (Arm)]

On 2/10/26 05:34, Wenchao Hao wrote:
> When do_anonymous_page() creates mappings for huge pages, it currently sets
> the access bit for all mapped PTEs (Page Table Entries) by default.
>
> This causes an issue where the Referenced field in /proc/pid/smaps cannot
> distinguish whether a page was actually accessed.

What is the use case that cares about that?

What we have right now is the exact same behavior as if you would get a 
PMD THP that has a single access+dirty bit at fault time.

Also, architectures that support transparent PTE coalescing will not be 
able to coalesce until all PTE bits are equal.

This level of imprecision is to be expected with large folios that only 
have a single access+dirty bit.

--
Cheers,

David