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Fri, 27 Feb 2026 22:50:59 +0530 (IST) Message-ID: <7d65b7a0-9bc3-4fb6-b25f-58b0e07c2ad8@zohomail.in> Date: Fri, 27 Feb 2026 22:50:57 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] mm/vmalloc: vrealloc() shrink TODO - seeking direction before implementing To: Danilo Krummrich , Uladzislau Rezki Cc: linux-mm@kvack.org, akpm@linux-foundation.org, aliceryhl@google.com References: <29e454bc-5a46-43b2-80b0-4d8d93e3feae@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-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: C8F24C0008 X-Stat-Signature: mcuqsdaedrbbnmyytqfua8jttzsnwt9q X-HE-Tag: 1772212883-544535 X-HE-Meta: U2FsdGVkX1/olS8VE2wiSrM6Ooam8IybxdHY7a46bpj38mKg4Qixys9IJVFJ3x98LbOlqMFxiP/DWH9Vod87V2V3IvZ+USiBd2FCg/aYzIxV7SkK6uaI1CPd4a3NAgmffnFYz3IZgBqzqT2p6Fr9waPBK+aOfqasiIQvy/5it0FkpzT0rVg7gM0pg6I/g7Ir9nLc7+HjUGkOMdGttkQUfYxddQlyTzenCFE74zAf1ZDlAtYVLftpP6KPE/ChqXxGGUe+WMEoi9uIZC9cfCjFl/c518ehniipSiuloGz5VHjjnN1ekgTkMamu2kGG7zC+NNKos0urZJ6idU2XRGnSE3uGRvVuHL6C+iLEmH1D6IydJrXqKLKL2u3lUzsFVg9hnkRVFYBd0LzBNkxO91aRFLXrmMnO6VV+g+dT+HjKODCAz5wDDqPRwlrCpgccbSzTT3hK+dZi6Empuad6gQUPPL4SK6486STSfkRRP2U6qsXh0/eNIZwTgQuyZT4OXNb5/R0Nh7NXeJrNuIXbQ64ciYN3GCZ6klt0mBV3QQAlhjzHNbOWHKuuqcEWkOk+aRdhR4xDq1aKg2zOBk39spgI6ODW9qSLCSGktl5CMCXmOA2SoCRqKUCU1Ri6i6aX2yCGe05lEOXHiVyimMr+4HE17mNh11QIgnXOq3T1kTQ2BsDSXlGPjz/VFTpi99ZGLKlz3P46xg5NPIaML9MuuCKgx/tXS4VsdcNOToMKRUNV9DEV452b9Kbp4Yu422VdoQgcx/5hOZNqzl/zmGg/zek+vIyefH0KOAbsj0LcAEHAN9fcTWtwPvuRUhb9OoM+OrZmq32LtSKAJf5WGICIKHAroMkFOSwoFeGvMzc/LASfm8dnAnmp4KJtvXNeZIRABnDiHK3erKIOpsxg7SPTSnNAc4VY2D3FuwFZmPWiFcFrqcAIaLFQTjAfRjmmVHTB+SzD0JYbmplLCgE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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/ Shivam