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[(111.162.215.50)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 2092408523; Wed, 12 Aug 2026 16:04:23 +0800 From: Song Hu To: linux-mm@kvack.org, akpm@linux-foundation.org Cc: david@kernel.org, ljs@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, corbet@lwn.net, skhan@linuxfoundation.org, rdunlap@infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Song Hu Subject: [PATCH 1/2] Docs/ABI: document transparent_hugepage/shrink_underused Date: Wed, 12 Aug 2026 16:03:12 +0800 Message-ID: <20260812080313.330413-2-husong@kylinos.cn> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260812080313.330413-1-husong@kylinos.cn> References: <20260812080313.330413-1-husong@kylinos.cn> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 52A5740002 X-Stat-Signature: jhpekd48uui7sb1a8ptgsipb6c4f6f5i X-Rspam-User: X-HE-Tag: 1786521873-754519 X-HE-Meta: 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 SdIN/AQ2 yyYHi7LFVhKMryTPKg1v0AtbqdKj+WD9H8jAkRSlMaCRyHBORrgLRZLpgQJlBs+hCKYuHJJp80yT66FsieOGEBBe92VN9rWaSMMSpoKjTgAVRiao= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The shrink_underused knob was added in commit 81d3ff3c6f76 ("mm: add sysfs entry to disable splitting underused THPs") but is missing from Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage, although transhuge.rst already documents it. Add the ABI entry. Signed-off-by: Song Hu --- .../ABI/testing/sysfs-kernel-mm-transparent-hugepage | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage b/Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage index 7bfbb9cc2c11..bbdfae2c0caa 100644 --- a/Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage +++ b/Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage @@ -10,9 +10,19 @@ Description: - hpage_pmd_size - khugepaged - shmem_enabled + - shrink_underused - use_zero_page - subdirectories of the form hugepages-kB, where is the page size of the hugepages supported by the kernel/CPU combination. See Documentation/admin-guide/mm/transhuge.rst for details. + +What: /sys/kernel/mm/transparent_hugepage/shrink_underused +Date: Sep 2024 +Contact: Linux memory management mailing list +Description: Reading and writing this file controls whether khugepaged + splits underused transparent huge pages (THPs) under memory + pressure. A THP is considered underused when its number of + zero-filled pages is above max_ptes_none. Enabled by default; + writing 0 disables the splitting and 1 enables it. -- 2.43.0