From: David Hildenbrand <david@redhat.com>
To: Kiryl Shutsemau <kirill@shutemov.name>,
Lance Yang <lance.yang@linux.dev>
Cc: akpm@linux-foundation.org, Liam.Howlett@oracle.com,
baohua@kernel.org, baolin.wang@linux.alibaba.com,
dev.jain@arm.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, lorenzo.stoakes@oracle.com,
npache@redhat.com, ryan.roberts@arm.com, usamaarif642@gmail.com,
ziy@nvidia.com
Subject: Re: [PATCH v2 1/1] mm: skip mlocked THPs that are underused early in deferred_split_scan()
Date: Mon, 8 Sep 2025 13:32:05 +0200 [thread overview]
Message-ID: <9a0c07b9-5bf0-4251-8609-fbaf0ca75bf9@redhat.com> (raw)
In-Reply-To: <niywtremc5kfhs3lenmfxvbiiizyexnaw3m25twedmzovfoeno@lk2o46tfdklk>
On 08.09.25 12:38, Kiryl Shutsemau wrote:
> On Mon, Sep 08, 2025 at 05:07:41PM +0800, Lance Yang wrote:
>> From: Lance Yang <lance.yang@linux.dev>
>>
>> When we stumble over a fully-mapped mlocked THP in the deferred shrinker,
>> it does not make sense to try to detect whether it is underused, because
>> try_to_map_unused_to_zeropage(), called while splitting the folio, will not
>> actually replace any zeroed pages by the shared zeropage.
>
> It makes me think, does KSM follows the same logic as
> try_to_map_unused_to_zeropage()?
>
> I cannot immediately find what prevents KSM from replacing zeroed mlocked
> folio with ZERO_PAGE().
>
> Hm?
I assume if you're using mlock and at the same time enable KSM for a
process/VMA, you're doing something wrong.
In contrast, THP is supposed to be transparent (yeah, I know ...).
--
Cheers
David / dhildenb
next prev parent reply other threads:[~2025-09-08 11:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-08 9:07 Lance Yang
2025-09-08 9:12 ` David Hildenbrand
2025-09-08 9:27 ` Lance Yang
2025-09-08 10:38 ` Kiryl Shutsemau
2025-09-08 11:32 ` David Hildenbrand [this message]
2025-09-08 11:44 ` Kiryl Shutsemau
2025-09-08 12:04 ` David Hildenbrand
2025-09-08 12:45 ` Kiryl Shutsemau
2025-09-08 13:00 ` Lance Yang
2025-09-08 11:32 ` Lance Yang
2025-09-08 14:28 ` Usama Arif
2025-09-08 16:18 ` Lorenzo Stoakes
2025-09-09 6:23 ` Baolin Wang
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