Re: [PATCH 2/6] mm/damon/ops-common: handle hugetlb folios in folio mkold/young rmap walkers

[SJ Park <sj@kernel.org>]

On Sun, 30 Aug 2026 09:13:33 -0700 SJ Park <sj@kernel.org> wrote:

> On Sun, 30 Aug 2026 05:28:55 +0000 sashiko-bot@kernel.org wrote:
[...]
> > [Severity: Medium]
> > Will mmu_notifier_test_young() miss accesses within shattered huge pages here?
> > 
> > Since the kernel's mmu_notifier_test_young() API does not take a size
> > parameter, passing only the base address of the huge page means it will
> > only evaluate the first base page.
> > 
> > For secondary MMUs like KVM EPT that map huge pages as multiple smaller
> > pages, wouldn't accesses to other subpages within the huge page be completely
> > missed? This could cause DAMON to classify the huge page as colder than it
> > actually is, which might lead to inappropriate reclaim or migration decisions.
> 
> This is also a pre-existing issue.  I will work on fixing this.

Actually, the curernt implementation is correct.  The goal here is to know if
the single byte of the address is accessed.  It works in page granularity for
most cases due to limitations.  That's not the intention.  So I think this can
just be as-is.


Thanks,
SJ

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