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Wed, 25 Feb 2026 15:19:36 -0800 (PST) Received: from fedora ([2603:8080:10f0:ab80::1382]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7d58644dd17sm332465a34.5.2026.02.25.15.19.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Feb 2026 15:19:36 -0800 (PST) Date: Wed, 25 Feb 2026 15:19:33 -0800 From: "Vishal Moola (Oracle)" To: lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org Cc: Matthew Wilcox , David Hildenbrand , Mike Rapoport Subject: [LSF/MM/BPF TOPIC] Separately allocating memdescs from struct page Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspam-User: X-Rspamd-Queue-Id: B552B1A0004 X-Rspamd-Server: rspam02 X-Stat-Signature: 3q4kmsixy3cou7pqwbi96g5pxw4n13gn X-HE-Tag: 1772061577-143264 X-HE-Meta: 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 1mB0D3L5 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: As part of the overarching project to shrink struct page, we've been creating memdescs that currently function as wrappers around it[1]. Until we separately allocate memdescs, we won't be able to shrink the page. We're getting close to being able to allocate memdescs separately from struct page, and I'd like to propose the topic to discuss how we want to go about it. We already have Matthew's PoC for ptdescs[2]. I've taken that on, but we're still running into issues for now... Heres a non-exhaustive list of things I'd like to discuss: - What memdescs to separate allocate for shrinking the page right now - What are the implications of separate allocations - Should we separately allocate one at a time, or all at once - How the APIs would look - Are there other generic fields to be cautious about (i.e. memcg) I imagine Matthew might have a broader State of the Page talk too, so this would be more in-depth. Possibly focused on ptdesc & slab (as the two we're actively looking at right now). [1] https://kernelnewbies.org/MatthewWilcox/Memdescs [2] https://lore.kernel.org/linux-mm/20251020001652.2116669-1-willy@infradead.org/