From: Dev Jain <dev.jain@arm.com>
To: Wei Yang <richard.weiyang@gmail.com>, Lance Yang <lance.yang@linux.dev>
Cc: linux-mm@kvack.org, baolin.wang@linux.alibaba.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 09:28:34 +0530 [thread overview]
Message-ID: <811bea18-30d0-446f-8840-d99698a6a9ba@arm.com> (raw)
In-Reply-To: <20251112034008.ojwghkko74psu65v@master>
On 12/11/25 9:10 am, Wei Yang wrote:
> On Wed, Nov 12, 2025 at 10:37:06AM +0800, Lance Yang wrote:
>>
>> 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>
>>
> Thanks for the review.
>
> I'm currently evaluating the use of SCAN_NULL versus SCAN_NONE. It seems their
> usage in the current code is intermixed, and I'm questioning if there's a
> strong, practical reason to maintain a distinction between these two states.
> Should they be unified?
There was some discussion about that in this thread:
https://lore.kernel.org/all/v5ivpub6z2n2uyemlnxgbilzs52ep4lrary7lm7o6axxoneb75@yfacfl5rkzeh/
There are some cleanups mentioned in the thread which you can try if you want :)
next prev parent reply other threads:[~2025-11-12 3:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-12 2:00 Wei Yang
2025-11-12 2:37 ` Lance Yang
2025-11-12 3:40 ` Wei Yang
2025-11-12 3:58 ` Dev Jain [this message]
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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