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Tue, 3 Mar 2026 02:47:38 +0530 (IST) Message-ID: <6212beb0-3b80-446a-9577-e94889fdc5a5@zohomail.in> Date: Tue, 3 Mar 2026 02:47:37 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] mm/vmalloc: vrealloc() shrink TODO - seeking direction before implementing To: Uladzislau Rezki Cc: Danilo Krummrich , linux-mm@kvack.org, akpm@linux-foundation.org, aliceryhl@google.com References: <29e454bc-5a46-43b2-80b0-4d8d93e3feae@zohomail.in> <7d65b7a0-9bc3-4fb6-b25f-58b0e07c2ad8@zohomail.in> Content-Language: en-US From: Shivam Kalra In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ZohoMailClient: External X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 496E8C0007 X-Stat-Signature: 7e9xbn4xs5go7f97rpdp5g1xyqqomnnr X-Rspam-User: X-HE-Tag: 1772486279-404117 X-HE-Meta: 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 smymQYql phRANmUvm9nFblUfy9e5buAkyQly8h2u/swVZJS1/BAwJv1DLaBwUU364Lv89DxyOVoTLZCNK2ukI4/vYlkT292eDdx7zFP13x6KJan7WdqjDfJnkmD9ceMuhOd/Uk3u508IrsRiZPTUV8f14fb4TtPOt1AqLu0n+nucUZdN6npypd3G/wppM0CsWtcwFLTHzbNNmtp033dgzlUjSx4rroqZPoIxTzl+PERSzXD3xZ8VyzvFc/Qtb3aafxLpimnOr5P06jjDc7zEYi3U/hQiiNQVyux2rIQm33t6kiMUXHAlgsUYTFQxkDgNuJUVgUoaW1xlbCLxZ1XrFtFPWNEx8BWqmkj8+ckhBiTjsqK4OB0DynI/OYJK8a7TUcKKMizdTjEHD Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 02/03/26 14:42, Uladzislau Rezki wrote: > 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 Cross posting the link to the patch series https://lore.kernel.org/all/20260302-vmalloc-shrink-v1-0-46deff465b7e@zohomail.in/