From: Nico Pache <nico.pache@linux.dev>
To: Barry Song <baohua@kernel.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>, Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
"Liam R. Howlett" <liam@infradead.org>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Lance Yang <lance.yang@linux.dev>,
Usama Arif <usama.arif@linux.dev>,
Kiryl Shutsemau <kas@kernel.org>, Yu Zhao <yuzhao@google.com>,
Xu Xin <xu.xin@linux.dev>,
Chengming Zhou <chengming.zhou@linux.dev>,
Matthew Brost <matthew.brost@intel.com>,
Joshua Hahn <joshua.hahnjy@gmail.com>,
Byungchul Park <byungchul@sk.com>,
Gregory Price <gourry@gourry.net>,
Ying Huang <ying.huang@linux.alibaba.com>,
Alistair Popple <apopple@nvidia.com>,
Usama Arif <usamaarif642@gmail.com>,
aarcange@redhat.com
Subject: Re: [PATCH v2 1/2] mm/huge_memory.c: skip zero-page remapping when underused THP shrinker is disabled
Date: Sun, 25 Oct 2026 15:48:43 -0600 [thread overview]
Message-ID: <e865f7f0-087c-4fe5-b729-6e6946cd20f6@linux.dev> (raw)
In-Reply-To: <CAGsJ_4zUVpBJazRxc1CzN6u5XvpUaGnaf-_7JMz-rGK_ZTYMtw@mail.gmail.com>
On 10/25/26 2:28 PM, Barry Song wrote:
> On Mon, Oct 26, 2026 at 1:40 AM Nico Pache (Red Hat)
> <nico.pache@linux.dev> wrote:
>>
>> The zero-page remapping in __folio_split() was added to support the
>> underused THP shrinker. When the shrinker is disabled via
>> shrink_underused, gate TTU_USE_SHARED_ZEROPAGE on split_underused_thp
>> to avoid scanning subpages for zero content unnecessarily.
>>
>> Suggested-by: David Hildenbrand <david@kernel.org>
>> Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp")
>> Signed-off-by: Nico Pache <nico.pache@linux.dev>
>
> is b1f202060afe a correct fixes tag? as
> commit b1f202060afe has no even "split_underused_thp" there.
I believe so. IIUC these two series were merged together. While
81d3ff3c6f7 introduces the toggle, b1f202060afe is where the behavior
started.
I guess you could argue that the Fixes should include both?
Not entirely sure!
-- Nico
>
> it was introduced by 81d3ff3c6f7 ("mm: add sysfs entry to disable
> splitting underused THPs").
next prev parent reply other threads:[~2026-10-25 21:49 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-25 17:39 [PATCH v2 0/2] MM: Tighten control over zero-page remapping Nico Pache (Red Hat)
2026-10-25 17:39 ` [PATCH v2 1/2] mm/huge_memory.c: skip zero-page remapping when underused THP shrinker is disabled Nico Pache (Red Hat)
2026-10-25 20:28 ` Barry Song
2026-10-25 21:48 ` Nico Pache [this message]
2026-10-26 4:52 ` Barry Song
2026-10-26 20:02 ` Nico Pache
2026-10-26 20:58 ` Barry Song
2026-10-26 21:33 ` Nico Pache
2026-10-26 17:41 ` sashiko-bot
2026-10-25 17:39 ` [PATCH v2 2/2] mm/ksm: prevent zero-page remapping during ksmd-triggered THP splits Nico Pache (Red Hat)
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