From: Lance Yang <lance.yang@linux.dev>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: linux-mm@kvack.org, baolin.wang@linux.alibaba.com,
dev.jain@arm.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com,
npache@redhat.com, baohua@kernel.org, akpm@linux-foundation.org,
david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com
Subject: Re: [PATCH] mm/khugepaged: continue to collapse on SCAN_PMD_NONE
Date: Wed, 12 Nov 2025 10:37:06 +0800 [thread overview]
Message-ID: <06096f8b-4da0-4b5c-af3c-fd8871437c16@linux.dev> (raw)
In-Reply-To: <20251112020031.25350-1-richard.weiyang@gmail.com>
On 2025/11/12 10:00, Wei Yang wrote:
> SCAN_PMD_NONE means current pmd is empty, but we can still continue
> collapse next pmd range.
Right, bailing out of the whole MADV_COLLAPSE request just because
we encounter one empty PMD is too strict ...
It makes sense to treat SCAN_PMD_NONE like the other whitelisted cases
(e.g., SCAN_PMD_NULL).
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> ---
LGTM.
Reviewed-by: Lance Yang <lance.yang@linux.dev>
> mm/khugepaged.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 7e8cb181d5bd..4c2217076ad3 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -2835,6 +2835,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start,
> goto handle_result;
> /* Whitelisted set of results where continuing OK */
> case SCAN_PMD_NULL:
> + case SCAN_PMD_NONE:
> case SCAN_PTE_NON_PRESENT:
> case SCAN_PTE_UFFD_WP:
> case SCAN_LACK_REFERENCED_PAGE:
next prev parent reply other threads:[~2025-11-12 2:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-12 2:00 [PATCH] mm/khugepaged: continue to collapse on SCAN_PMD_NONE Wei Yang
2025-11-12 2:37 ` Lance Yang [this message]
2025-11-12 3:40 ` Wei Yang
2025-11-12 3:58 ` Dev Jain
2025-11-12 9:10 ` Wei Yang
2025-11-12 3:33 ` Dev Jain
2025-11-12 9:51 ` David Hildenbrand (Red Hat)
2025-11-12 9:51 ` David Hildenbrand (Red Hat)
2025-11-12 11:27 ` Wei Yang
2025-11-12 11:41 ` David Hildenbrand (Red Hat)
2025-11-13 2:44 ` Baolin Wang
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