Re: [PATCH REPOST 4/5] mm/damon/vaddr: extend apply_probes() for hugetlb

[Kunwu Chan <kunwu.chan@gmail.com>]

On Wed,  9 Sep 2026 07:04:06 -0700 SJ Park <sj@kernel.org> wrote:

> DAMON virtual address space operation set(vaddr) does not support
> hugetlb pages in apply_probes.  Extend it for hugetlb pages.
> 
> Signed-off-by: SJ Park <sj@kernel.org>
> ---
>  mm/damon/vaddr.c | 30 +++++++++++++++++++++++++++++-
>  1 file changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
> index 7c548ec0cf6b5..45239f05e113b 100644
> --- a/mm/damon/vaddr.c
> +++ b/mm/damon/vaddr.c
> @@ -598,6 +598,34 @@ static int damon_va_probe_pmd_entry(pmd_t *pmd, unsigned long addr,
>  	return 0;
>  }
>  
> +#ifdef CONFIG_HUGETLB_PAGE
> +static int damon_va_probe_hugetlb_entry(pte_t *pte, unsigned long hmask,
> +		unsigned long addr, unsigned long end, struct mm_walk *walk)
> +{
> +	struct damon_va_probe_walk_private *priv = walk->private;
> +	struct hstate *h = hstate_vma(walk->vma);
> +	struct folio *folio;
> +	spinlock_t *ptl;
> +	pte_t entry;
> +
> +	ptl = huge_pte_lock(h, walk->mm, pte);
> +	entry = huge_ptep_get(walk->mm, addr, pte);
> +	if (!pte_present(entry))
> +		goto out;
> +
> +	folio = pfn_folio(pte_pfn(entry));
> +	folio_get(folio);
> +	damon_va_probe_folio(priv->ctx, priv->r, folio);
> +	folio_put(folio);
> +
> +out:
> +	spin_unlock(ptl);
> +	return 0;
> +}
> +#else
> +#define damon_va_probe_hugetlb_entry NULL
> +#endif /* CONFIG_HUGETLB_PAGE */
> +
>  static void __damon_va_apply_probes(struct damon_ctx *ctx,
>  		struct mm_struct *mm,  struct damon_region *r)
>  {
> @@ -607,7 +635,7 @@ static void __damon_va_apply_probes(struct damon_ctx *ctx,
>  	};
>  	struct mm_walk_ops damon_probe_walk_ops = {
>  		.pmd_entry = damon_va_probe_pmd_entry,
> -		.hugetlb_entry = NULL,
> +		.hugetlb_entry = damon_va_probe_hugetlb_entry,
>  	};
>  	unsigned long addr = r->sampling_addr;
>  
> -- 
> 2.47.3
> 

Hi SJ,

Reviewed patches 1-4, with particular attention to the vaddr prep/apply flow, 
the filter handling shared with paddr, and the hugetlb page-walk path. 
The changes look consistent with the existing DAMON interfaces 
and page-walk semantics. 

Reviewed-by: Kunwu Chan <kunwu.chan@gmail.com> 

Thanks,
Kunwu

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