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 CBA66C021B8 for ; Tue, 4 Mar 2025 08:22:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5C90D280002; Tue, 4 Mar 2025 03:22:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 551BA280001; Tue, 4 Mar 2025 03:22:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3CA32280002; Tue, 4 Mar 2025 03:22:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 1B33D280001 for ; Tue, 4 Mar 2025 03:22:17 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id D8A7DB694F for ; Tue, 4 Mar 2025 08:22:16 +0000 (UTC) X-FDA: 83183176272.16.3F55180 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) by imf16.hostedemail.com (Postfix) with ESMTP id AA01C180007 for ; Tue, 4 Mar 2025 08:22:14 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=pTtO6DWO; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=RZjuCsUd; dkim=pass header.d=suse.de header.s=susede2_rsa header.b="y3mrGdx/"; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=AwW4QRns; spf=pass (imf16.hostedemail.com: domain of osalvador@suse.de designates 195.135.223.130 as permitted sender) smtp.mailfrom=osalvador@suse.de; dmarc=pass (policy=none) header.from=suse.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1741076534; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=A1iGbelaTALv5TJMxtK+qrnTKCCp2cmpTL/B5DdK1Vs=; b=6mmsRusLECZ3YCIfakwTVrzp3+1kZleJUsZaljp1zCDcoW1ZwoC9UsXHH4P85b0jN9uzEA JM9/EFsQ0XjHU715UIq2/4HRexuThuVAcOCm89MB+IkfZzVR8vX0qotkLjtTjqoOwmj70T mIuljhyprNrxTR8JrRQKgKK4Wozmlvs= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=pTtO6DWO; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=RZjuCsUd; dkim=pass header.d=suse.de header.s=susede2_rsa header.b="y3mrGdx/"; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=AwW4QRns; spf=pass (imf16.hostedemail.com: domain of osalvador@suse.de designates 195.135.223.130 as permitted sender) smtp.mailfrom=osalvador@suse.de; dmarc=pass (policy=none) header.from=suse.de ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1741076534; a=rsa-sha256; cv=none; b=8qJLehDK4jrrYnR88mSiH6tewsChL3r5nXMFn/atmBGhspfSviQvTaRyR2dpejBYWbJJ+t oIDRZyWIOseUHpUwMT2c5XlnoBsF78tzi2HvacZwUUjKR6LbYm9GAAvbklYG0bsR8gJ420 fyg4zo+zuTb1ZRwGUwhtIqy7UG27ONY= Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id E7F952116B; Tue, 4 Mar 2025 08:22:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1741076533; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=A1iGbelaTALv5TJMxtK+qrnTKCCp2cmpTL/B5DdK1Vs=; b=pTtO6DWOv7HVdk0DopBnr7FBs8lw+CeB94qhhMw2AzEQL9sxfuWr1xxuh2gI7tyg65XGmX +c42tFVFn7IWwsRc8SVNt0n6BuwUOlQWF4/M1LWtK/L9xs+DOWi6dq/FVS480S5BGvJMpy eHepKA2WZaFZfy9d3+PZat0r0eCGW6o= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1741076533; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=A1iGbelaTALv5TJMxtK+qrnTKCCp2cmpTL/B5DdK1Vs=; b=RZjuCsUd4QbjDaC7142C8e/UHlSC76MGn1CSiUWw1dBFOm9j2W6ql1HL0oqVlHlbjAUNfi 98ackGqGs6RjQ5CA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1741076532; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=A1iGbelaTALv5TJMxtK+qrnTKCCp2cmpTL/B5DdK1Vs=; b=y3mrGdx/kdMYr18Ca1TcbYYDL0goAAGV9UL34f4VsfPiCg1ZrWG8tMfXnCSZc6yw97BgqW pJNuoF1opafT1K6XudP9sCdAAbsof70pwSmB1vHWdKF4Y2/KHPSKvup/sVnGsbS5NVOuhP p/eBEihk36BtBbOJ4FCIKBNgEnopXOE= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1741076532; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=A1iGbelaTALv5TJMxtK+qrnTKCCp2cmpTL/B5DdK1Vs=; b=AwW4QRnsWlUItyWFe4fUIeV27z/cVT8byjaRV6l7ZXGtlYgoLGAH4lxFqGYx4BA0GOJokC WyMOnHCCirCzu+Aw== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 635121393C; Tue, 4 Mar 2025 08:22:11 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id dfxzFTO4xmfRNgAAD6G6ig (envelope-from ); Tue, 04 Mar 2025 08:22:11 +0000 Date: Tue, 4 Mar 2025 09:22:09 +0100 From: Oscar Salvador To: Zhenhua Huang Cc: anshuman.khandual@arm.com, catalin.marinas@arm.com, david@redhat.com, will@kernel.org, ardb@kernel.org, ryan.roberts@arm.com, mark.rutland@arm.com, joey.gouly@arm.com, dave.hansen@linux.intel.com, akpm@linux-foundation.org, chenfeiyang@loongson.cn, chenhuacai@kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, quic_tingweiz@quicinc.com, stable@vger.kernel.org Subject: Re: [PATCH v9] arm64: mm: Populate vmemmap at the page level if not section aligned Message-ID: References: <20250304072700.3405036-1-quic_zhenhuah@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250304072700.3405036-1-quic_zhenhuah@quicinc.com> X-Rspamd-Action: no action X-Rspam-User: X-Stat-Signature: 8n7d1xmos6tw4sisa6ezs3r1gj8i5u7x X-Rspamd-Queue-Id: AA01C180007 X-Rspamd-Server: rspam07 X-HE-Tag: 1741076534-239873 X-HE-Meta: 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 2gYNef2x wQ/jfl64ZEHRWwEJTrKsWJWefQGSguAH1pfyIgmSXq9gyJ/1tONYIaKKu/0GkEf/PYjpNiqSUl8rxXVA3N7CjjmMpjegIACP5xF2ykgEsExup4+HwkWkKzoHf1lvG3cDiXBK2TlG9DyMQwy8uqB9Mc81eRpQq8wsXA1/I9wHvhU+Zv3ZZI2HCxhelNRraV1JxuVJR/uhLctduETFNGdk+eVwIcVQpeBGRIc1R3xYrxzKZvr0A09LF1fuU16n45RcXbKIbNmkOy8UunEZvd//kVFbuuX4Szs6F6ZulEpSKVzWpIndJk13b3z9iBlov40rchZVuiPu0lp2y8YRKNS055JoR6vWW+yADtu/6+W6r6X1aacLr/sRl3WUyQQ== 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: On Tue, Mar 04, 2025 at 03:27:00PM +0800, Zhenhua Huang wrote: > On the arm64 platform with 4K base page config, SECTION_SIZE_BITS is set > to 27, making one section 128M. The related page struct which vmemmap > points to is 2M then. > Commit c1cc1552616d ("arm64: MMU initialisation") optimizes the > vmemmap to populate at the PMD section level which was suitable > initially since hot plug granule is always one section(128M). However, > commit ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") > introduced a 2M(SUBSECTION_SIZE) hot plug granule, which disrupted the > existing arm64 assumptions. > > The first problem is that if start or end is not aligned to a section > boundary, such as when a subsection is hot added, populating the entire > section is wasteful. > > The next problem is if we hotplug something that spans part of 128 MiB > section (subsections, let's call it memblock1), and then hotplug something > that spans another part of a 128 MiB section(subsections, let's call it > memblock2), and subsequently unplug memblock1, vmemmap_free() will clear > the entire PMD entry which also supports memblock2 even though memblock2 > is still active. > > Assuming hotplug/unplug sizes are guaranteed to be symmetric. Do the > fix similar to x86-64: populate to pages levels if start/end is not aligned > with section boundary. > > Cc: # v5.4+ > Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") > Acked-by: David Hildenbrand > Signed-off-by: Zhenhua Huang Reviewed-by: Oscar Salvador -- Oscar Salvador SUSE Labs