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b=oaAm6ZoL0bGjZNnnDPIJ7BXckZpQ3BmpgPnW5gWbYQfp7gpAkJNt7lLc+JWkrobJn brbcqfuvNBIv9dWGRsvq7NaFzyKYSvtcA2/8a94AHmaMA2JWt+y0hwvPw24TtPQBoC hLPYaqBg2GMJg7oJ5SWcWjj7huO84D6OKabzAxEKGI6uFbYT7oCrAkt1d+FuRG6KhG SDUGkoKUPa8OQhqp3rSW2FAQ8h/H0FGSWNdL/F+eP00BJ6sfSLNVvY3PjdpC9phucQ MX8Bbtq0Ra45++zyGyAZpYMm7RwgR/q+Ve4aMEGj65gnhNnCoCe4f9D6z+txZcM+nU TeJQCS0LT9DXQ== Date: Wed, 12 Aug 2026 09:58:33 +0100 From: "Lorenzo Stoakes (ARM)" To: Song Hu Cc: linux-mm@kvack.org, akpm@linux-foundation.org, david@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 Subject: Re: [PATCH 1/2] Docs/ABI: document transparent_hugepage/shrink_underused Message-ID: References: <20260812080313.330413-1-husong@kylinos.cn> <20260812080313.330413-2-husong@kylinos.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260812080313.330413-2-husong@kylinos.cn> X-Rspam-User: X-Stat-Signature: m9fnqtadqryr8hbe4f87r1n5zhkx5ox9 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1F7E320006 X-HE-Tag: 1786525134-62541 X-HE-Meta: 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 qOz3E1k3 ftuQY+ZNpBNmhI8GR4xGGGKy8+ptzyGxtL+3Zpfs+mY3/yV6TMH945X9iljwYvr8n3hayxd0KhDMsW/L5Vv3RcoeuuHn0wBSvSIZ55EPHlVUDK0XBU+yx6ZMn+fC0eplzJujUMUWU1KImMij/LsxC8Vju22rJkPA/9S770zYWjj9MRZ5Ke+cthB3/gRz3G0WwPUyhTbuzi9WPoZSVe+K0aMjkJZrUKd3rx4Fi3nr1axPU3wNI8Wpfvb2fHFGALtst1iRzco1POrH+hREjTuJKUw/xP18Iqw3qJKfMpGgdBIBhV7oiZLNY33NF3QFEdxGGrUKSunth4HBWetDoRJou6Luq3alzwWn4F2axSRy0nMzhNaI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Please don't send patch series like this - we really require a cover letter if patch count > 1, and every patch should reply to the cover letter. On Wed, Aug 12, 2026 at 04:03:12PM +0800, Song Hu wrote: > 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. Hmm what even is this file? :) What is the contract on this file? > > 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 I mean I guess fine for consistency. > - use_zero_page > - subdirectories of the form hugepages-kB, where > is the page size of the hugepages supported by the kernel/CPU > combination. But we already handwave literally everything else here.... > > 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. Nothing else is documented in this file so why is this getting special treatment? And why is it backdated to Sep 2024?... Drop it please. > -- > 2.43.0 > -- Cheers, Lorenzo