From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C35E9C4167B for ; Mon, 4 Dec 2023 12:26:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2DFDA6B02BE; Mon, 4 Dec 2023 07:26:34 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 290446B02C1; Mon, 4 Dec 2023 07:26:34 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 157D26B02C3; Mon, 4 Dec 2023 07:26:34 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 032BB6B02BE for ; Mon, 4 Dec 2023 07:26:34 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id B1B03C0210 for ; Mon, 4 Dec 2023 12:26:33 +0000 (UTC) X-FDA: 81529059066.24.EB77A7B Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf05.hostedemail.com (Postfix) with ESMTP id BD278100009 for ; Mon, 4 Dec 2023 12:26:31 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=none; spf=pass (imf05.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1701692791; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kMWNDWarIcZoO1/8XAi6ojh4BZb6bpfGSf2KBFZTWaw=; b=H+9m0fc8rd1tGJWagf+Fb59ADsPqWNFfVm4qnTAu/Kw5H2+/ALod0a6Xiotg5elsdvHVIg G7E4RwhjVSL5SF91knRzrFQaSP/lwuAMSknLimwnTZHEErHSPlxH9VVfP5lAV1ih2TFvZL J5y7Pi1QDbXWNLsUmy5RZ6eLaOucKDQ= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=none; spf=pass (imf05.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1701692791; a=rsa-sha256; cv=none; b=GSkITe/CPLo66/JlY81MW+reuLeqKP4LlTo6z4ojlxnRm96YWynqEBV693kJPM4eQIR7ee 9aam8rLUb3eMop1deoPj9pqgr7cEpwN+alCJ10/JjQ2mRj41JecbJzql3ETLvlYwHqnD3F gcgnL29jNSQpED8ZtlNKFvGWc1beeWA= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 492471424; Mon, 4 Dec 2023 04:27:18 -0800 (PST) Received: from [10.57.73.130] (unknown [10.57.73.130]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8B0583F5A1; Mon, 4 Dec 2023 04:26:28 -0800 (PST) Message-ID: <6dd6164a-1dd5-46e7-bcf7-b62ff5c6e8ec@arm.com> Date: Mon, 4 Dec 2023 12:26:27 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 4/4] mm/mmu_gather: Store and process pages in contig ranges Content-Language: en-GB To: Zi Yan , Matthew Wilcox Cc: Will Deacon , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Peter Zijlstra , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , David Hildenbrand , Yu Zhao , "Kirill A. Shutemov" , Yin Fengwei , Yang Shi , "Huang, Ying" , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230810103332.3062143-1-ryan.roberts@arm.com> <20230810103332.3062143-5-ryan.roberts@arm.com> <800937DA-BAD0-4C60-B155-AECCA21E955E@nvidia.com> <1a0f5cb8-421c-4f28-a986-f3c381406e81@arm.com> <90EC4C0D-0254-4B93-AFD5-3C09580A77DE@nvidia.com> From: Ryan Roberts In-Reply-To: <90EC4C0D-0254-4B93-AFD5-3C09580A77DE@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: BD278100009 X-Rspam-User: X-Stat-Signature: b81xy8yu74a4nhrbe953zdmz5qcr5bob X-Rspamd-Server: rspam01 X-HE-Tag: 1701692791-922859 X-HE-Meta: U2FsdGVkX1+xisCdwzcYWXEMAM1qmIk/cmzwYHgsy1K3Roinl8fU91kZQXuR4rg9CY5Oy0UIKhKFT0XgDE0vrKLSN75/6daG/ckniyuuMGGPBi36vxMRW0eYcvTN1CqW+BNoET4hOPUd0Y2d6Lqj5YvpvruEgyxCkPnRoL9cENEwKiUNrkhfr36WmUYjZHKiXWrtV4UbgiKKCiJ6vJwPlY78arpN5aHJCG77qHqhc7VIAxgMCLaqZBPpPqCpeRFCnmrtBvQxwyB0wQI/sHntr6hlt0hAcfNkWiGGOpKRGs70IxvHA2jcP7hDKStio3VaItaUe+2oiIMiE0uyzGLz/gAb+3DwXc+1FAKLF8zDVlUTkgA33q8q0G3Hwjd+F5oLVXKpSk3CUD4BFDDtArb5LPY7GME0tMFwliehN6hyvJx3u1GVbAfxGUY343mae1Est7Gji+Giytt58zRdaMXm8FPRZvX8DiA7Gdxz0AJEEdImqAxeWMSZN9R+5ifjqMCxhomXTNbNakLB0idekQxQ5K10Pk+RPTUEw+FFK3uyz3DU1OmcNIHwtL6ifjkIkjRJ5rjUWSypff6Q6bz3YGZ81xYFaqOhhvSEQdHG3uDtFM7z5KiT+lfGyLrN8a7liRwezGZOrEHH4o6e3BMxTpnqjpu2gqYfKaAPhC5A/VDQzMBoaDyAupNmJAus+KDZlGae/Bng/9z86drC2I4ZoPOLIxXS9bLlIxB9viMndEdQ2+kVSspHdwUJZACJgfUk8EoCSgzvSwxRhZisakPW4fwR7ss2Om/UwGt6jVF/fHJSJIXoDveRRQ+ZTavufsORXueXmmRDiubz7oJLPJaSsXGNuarsxesQbAMBr1yX/33jNzjOY2+/VHTye8NKFOkweDjFRiqSBml8hA9b8Tl4ke2VNP5KpbOcdsa27FhpeQZ0Ql9sHdo/gL68ur1IMwA3UlUVIAWi2scxjbPYf2A43q4 vBKJoqve /gmak4OsJWqco93xVkMujybfOVkI5LiSdWHcKytBcLHIj8BoFQhQG4BArFX743fukHtCU53odbraOdZySyRJ8wPYI/oj+nIiOAd0uzKERL0gOqSuGDba0Do+m/gtFuWfjrAfq+S9zLF1ToMwrLIa+fo4wJFFoYr5WInCktUxhi3neTAJaau4ucN3hHmqDPfkkpzVBspnYz3LTDdmyzMYxVEafVoIjDcYavqo0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: >>> >>> Also, struct page (memmap) might not be always contiguous, using struct page >>> points to represent folio range might not give the result you want. >>> See nth_page() and folio_page_idx() in include/linux/mm.h. >> >> Is that true for pages within the same folio too? Or are all pages in a folio >> guarranteed contiguous? Perhaps I'm better off using pfn? > > folio_page_idx() says not all pages in a folio is guaranteed to be contiguous. > PFN might be a better choice. Hi Zi, Matthew, Zi made this comment a couple of months back that it is incorrect to assume that `struct page`s within a folio are (virtually) contiguous. I'm not sure if that's really the case though? I see other sites in the source that do page++ when iterating over a folio. e.g. smaps_account(), splice_folio_into_pipe(), __collapse_huge_page_copy(), etc. Any chance someone could explain the rules? Thanks, Ryan