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Tue, 03 Mar 2026 19:35:07 -0800 (PST) Received: from [192.168.1.150] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7d586653f6asm15202012a34.19.2026.03.03.19.35.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 03 Mar 2026 19:35:06 -0800 (PST) Message-ID: Date: Tue, 3 Mar 2026 20:35:01 -0700 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/8] mm: globalize rest_of_page() macro To: Yury Norov , Sean Christopherson Cc: Jakub Kicinski , Andrew Morton , "David S. Miller" , "Michael S. Tsirkin" , Theodore Ts'o , Albert Ou , Alexander Duyck , Alexander Gordeev , Alexander Viro , Alexandra Winter , Andreas Dilger , Andrew Lunn , Anna Schumaker , Anton Yakovlev , Arnaldo Carvalho de Melo , Aswin Karuvally , Borislav Petkov , Carlos Maiolino , Catalin Marinas , Chao Yu , Christian Borntraeger , Christian Brauner , Claudio Imbrenda , Dave Hansen , David Airlie , Dominique Martinet , Dongsheng Yang , Eric Dumazet , Eric Van Hensbergen , Heiko Carstens , Herbert Xu , Ingo Molnar , Jaegeuk Kim , Jani Nikula , Janosch Frank , Jaroslav Kysela , Joonas Lahtinen , Latchesar Ionkov , Linus Walleij , Madhavan Srinivasan , Mark Brown , Michael Ellerman , Miklos Szeredi , Namhyung Kim , Palmer Dabbelt , Paolo Abeni , Paolo Bonzini , Paul Walmsley , Peter Zijlstra , Rodrigo Vivi , Simona Vetter , Takashi Iwai , Thomas Gleixner , Trond Myklebust , Tvrtko Ursulin , Vasily Gorbik , Will Deacon , Yury Norov , Zheng Gu , linux-kernel@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-block@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, dm-devel@lists.linux.dev, netdev@vger.kernel.org, linux-spi@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-nfs@vger.kernel.org, linux-crypto@vger.kernel.org, linux-mm@kvack.org, linux-perf-users@vger.kernel.org, v9fs@lists.linux.dev, virtualization@lists.linux.dev, linux-sound@vger.kernel.org References: <20260304012717.201797-1-ynorov@nvidia.com> <20260303182845.250bb2de@kernel.org> Content-Language: en-US From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/3/26 8:32 PM, Yury Norov wrote: > My motivation is that it helps to simplify constructions like this: > > - loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff), > - PAGE_SIZE - offset_in_page(dstoff)); > + loff_t cmp_len = min(rest_of_page(srcoff), rest_of_page(dstoff)); > > Or this: > > - if (folio_test_highmem(dst_folio) && > - chunk > PAGE_SIZE - offset_in_page(dst_off)) > - chunk = PAGE_SIZE - offset_in_page(dst_off); > - if (folio_test_highmem(src_folio) && > - chunk > PAGE_SIZE - offset_in_page(src_off)) > - chunk = PAGE_SIZE - offset_in_page(src_off); > + if (folio_test_highmem(dst_folio) && chunk > rest_of_page(dst_off)) > + chunk = rest_of_page(dst_off); > + if (folio_test_highmem(src_folio) && chunk > rest_of_page(src_off)) > + chunk = rest_of_page(src_off); > > To a point where I don't have to use my brains to decode them. I agree > it's an easy math. It's just too bulky to my (and 9p guys too) taste. The thing is, now I have to go lookup what on earth rest_of_page() does, whereas PAGE_SIZE - offset_in_page(page) is immediately obvious. It's a classic case of "oh let's add this helper to simplify things" which really just makes it worse, because now you have to jump to the definition of rest_of_page(). IOW, just no. -- Jens Axboe