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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Hugh Dickins , Baolin Wang , Jonathan Corbet , Shuah Khan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v4 1/3] mm/swap: colocate page-cluster sysctl with swap readahead Message-ID: References: <20260603-ch-swap-series-plus-folio-lru-cleanup-v4-0-ce0219e100d9@gmail.com> <20260603-ch-swap-series-plus-folio-lru-cleanup-v4-1-ce0219e100d9@gmail.com> Precedence: bulk X-Mailing-List: linux-doc@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: <20260603-ch-swap-series-plus-folio-lru-cleanup-v4-1-ce0219e100d9@gmail.com> On Wed, Jun 03, 2026 at 09:05:32PM +0800, Jianyue Wu wrote: > page_cluster and the vm.page-cluster sysctl are only used by swap-in > readahead in swap_state.c. Move them out of swap.c together with > swap_readahead_setup(), and make page_cluster static to that file. > > Rename swap_setup() while moving it as well. The helper is internal to > MM and now only sets up swap readahead defaults and its sysctl hook, so > the more specific name matches its reduced scope. > > swap_setup() previously lived in mm/swap.c, which is built > unconditionally, so the vm.page-cluster sysctl was registered also on > CONFIG_SWAP=n kernels. swap_readahead_setup() is now a no-op stub when > CONFIG_SWAP is disabled, so vm.page-cluster is no longer registered > there. The knob only tunes swap-in readahead and had no effect without > swap. > > Suggested-by: Baoquan He > Suggested-by: Barry Song > Signed-off-by: Jianyue Wu Suggested-by: Johannes Weiner Acked-by: Johannes Weiner