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Mon, 02 Mar 2026 01:12:13 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 2 Mar 2026 10:12:12 +0100 To: Shivam Kalra Cc: Danilo Krummrich , Uladzislau Rezki , linux-mm@kvack.org, akpm@linux-foundation.org, aliceryhl@google.com Subject: Re: [RFC] mm/vmalloc: vrealloc() shrink TODO - seeking direction before implementing Message-ID: References: <29e454bc-5a46-43b2-80b0-4d8d93e3feae@zohomail.in> <7d65b7a0-9bc3-4fb6-b25f-58b0e07c2ad8@zohomail.in> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7d65b7a0-9bc3-4fb6-b25f-58b0e07c2ad8@zohomail.in> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 268801A0011 X-Stat-Signature: oqk6h9ef5uppoza56naqpjheydwj8n1j X-HE-Tag: 1772442735-251457 X-HE-Meta: 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 h6CwA8wV V9c9GtRCOHenfL0FSYXAIbQU239FoAkTFVQ2EhTo68pZRnKQAYr+RyaUCcTqju82z7X+O0Vygcg3695sR2MR+QA6v3PzGTQ6Cm7D5gwBMmi7tn2sH1gA2xTIhy/kx58C6HaiGl1I4w4oCfruUZ8jJahSOn0CRNqD8Mnb/HrUN4y2vcd/N/L3vP7eEstufyaeuENR5QFHBc+s88H7KBCxxIGX7L8p1ZSUrEN+YaqZenG33ga72YUgeZv32+8mDm3xjHsU2s33RimVdQTjxVRUEO5S9c3kXDRW0GIOuGtWfibdqauSClVAYIbo63kxiEC5R+0LmDxL4/LdmsAkApe+phBjtPctrBEh80hLEI+141xzI9R2bZfI5tUduzhuL6El6z4yGtaUPR1wOJuX3uuz8rBfviGTmFw15TiqVeGSomdYe3pEb60IBoSpFoZiEI/JsCn2fd7FQM56eBJ8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello, Shivam! > On 19/02/26 22:31, Danilo Krummrich wrote: > > (Cc: Alice) > > > > On Thu Feb 19, 2026 at 5:57 PM CET, Uladzislau Rezki wrote: > >> I think we have 0 users of vrealloc(). It was added because of Rust folk > >> wanted this. > > > > We just gained a user with the Rust binder driver. > Hi Uladzislau, > > You mentioned concerns about there being no users and added complexity. > The Rust binder driver has a user of kvrealloc for long-lived resizable > arrays. I also have a patch series adding shrink_to support for these > allocations, which is now in char-misc-testing [1]. > > Given that there's now an active use case, I'd like to go ahead with > implementing the vrealloc shrink as described in the RFC- in-place tail > page freeing, skipping huge-page allocations. Happy to adjust the > approach based on your input. > > [1] > https://lore.kernel.org/all/20260216-binder-shrink-vec-v3-v6-0-ece8e8593e53@zohomail.in/ > Go ahead. Send out a path then we will see what we have. -- Uladzislau Rezki