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Fri, 6 Feb 2026 09:43:15 -0500 (EST) Date: Fri, 6 Feb 2026 14:43:10 +0000 From: Kiryl Shutsemau To: Gladyshev Ilya Cc: gorbunov.ivan@h-partners.com, artem.kuzin@huawei.com, stepanov.anatoly@huawei.com, alexander.grubnikov@huawei.com, David Hildenbrand , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Zi Yan , Harry Yoo , "Matthew Wilcox (Oracle)" , Yu Zhao , Baolin Wang , Will Deacon , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: make ref_unless functions unless_zero only Message-ID: References: <20260206133328.426921-1-gladyshev.ilya1@h-partners.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260206133328.426921-1-gladyshev.ilya1@h-partners.com> On Fri, Feb 06, 2026 at 01:33:02PM +0000, Gladyshev Ilya wrote: > There are no users of (folio/page)_ref_add_unless(page, nr, u) with > u != 0 [1] and all current users are "internal" for page refcounting API. > This allows us to safely drop this parameter and reduce function > semantics to the "unless zero" cases only, which will be optimized in > the following patch. > > If needed, these functions for the u!=0 cases can be trivially > reintroduced later using the same atomic_add_unless operations as before. > > [1]: The last user was dropped in v5.18 kernel, commit 27674ef6c73f > ("mm: remove the extra ZONE_DEVICE struct page refcount"). There is no > trace of discussion as to why this cleanup wasn't done earlier. > > Co-developed-by: Gorbunov Ivan > Signed-off-by: Gorbunov Ivan > Signed-off-by: Gladyshev Ilya > Acked-by: David Hildenbrand (Arm) Acked-by: Kiryl Shutsemau -- Kiryl Shutsemau / Kirill A. Shutemov