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b=NxcOvnqTLqnucN77/ABpJZAyzChmV2Fi0KnuSgNaUtL4FtePQ3yk+d58dIAGltofZ Dfd/Fh0av3tGTeKX9OydBN5Bj+R5YNfOzC142oLSyP5J5U69MtfW3Yx+T9zpe7L3fm aJhWxlVnp9/UFO2sCbrT4sLwqiZQ4kUtVvrm499OTClhrhujcTKhfgbUGE1LKO490b L6nOOPQS99TvdKGENVdlLz6UlkBVfZ4FhxRjgaPHR32thskI0EYAC6E4Jyq7GotH3Q 924JlasleBvAcWDtIghuv7dwqABEXCC60y14aDpcCVLGR8Acdi2AYiBbPpio2pG1xq G4riMK/2ozqiA== Message-ID: <89837004-b5c9-4b59-b795-3b79005379af@kernel.org> Date: Thu, 13 Aug 2026 12:00:30 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/8] Introducte Reserved THP To: Zi Yan , Qi Zheng , akpm@linux-foundation.org, ljs@kernel.org, baolin.wang@linux.alibaba.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, muchun.song@linux.dev, osalvador@suse.de, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, youngjun.park@lge.com, peterx@redhat.com, usama.arif@linux.dev, willy@infradead.org, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Qi Zheng References: From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: nuek4nsb5tfjbqhsdkfpqfru7rjzz49r X-Rspamd-Queue-Id: 3E09920006 X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1786615240-336327 X-HE-Meta: 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 UV9riI57 POmpDo8Omp/zQnYW4D2hwt0ddU2ImHX1fCryfilL184D9mBhxrSNR+b8Tu6a6u8onp/uTzlhk58yxWzUIuwANrkja5NQTrUY/VbNrW9m85pup5sDNmxSqS0ybQTCbGv94wl17hC1ChhJKqgjXuNlpivHnH3/s4ZfdZW21MzJnDnEggAhR6JfSJlEVjjiZNd3Uuix5Xll7u4VzKf1O/dnB5f/23nQNxXU3BAUMmcqFrFk2TXB974cq1rTOn07sJlj/e03v Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: ... digging through old mail. > > You mean the reservation should be done via some file handle, like > memfd, so that it is easy to apply memory policies to determine where > reserved memory locates? > > For existing hugetlb reservation, there is no fine control, like NUMA, > or cgroup, of the reserved free memory. > > Is that what you mean above? I guess, it's all tricky. hugetlb reservation is a mess. We better not make similar mistakes with THPs. [...] >>> 3.6 Remove Hugetlb >>> ------------------ >>> >>> Once reserved THP can completely replace the existing functions of hugetlb, we >>> can gradually remove Hugetlb, leaving only one huge page management system in >>> the kernel. >> >> I'm sorry, but no way this will work in any reasonable timeframe unless you >> mimic the exact user facing ABI -- and I don't think we'll gain a lot that way. >> >> I know, we all like to dream, but this just isn't feasible. > > Based on my understanding, the key takeway is that we want to have more > control over reserved memory, where to get the free memory, who gets how > much of the reserved memory, and more. yes, it's all very complicated. Slapping on some MADV_RESERVED_THP is just entirely the wrong way to tackle this. -- Cheers, David