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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4EB85EA8124 for ; Tue, 10 Feb 2026 15:00:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 91A256B0005; Tue, 10 Feb 2026 10:00:25 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8FB406B0089; Tue, 10 Feb 2026 10:00:25 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 828AF6B008A; Tue, 10 Feb 2026 10:00:25 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 72B386B0005 for ; Tue, 10 Feb 2026 10:00:25 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id F2A1F1405DE for ; Tue, 10 Feb 2026 15:00:24 +0000 (UTC) X-FDA: 84428857968.04.5D74860 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf10.hostedemail.com (Postfix) with ESMTP id 67462C0019 for ; Tue, 10 Feb 2026 15:00:22 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=none; spf=pass (imf10.hostedemail.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=catalin.marinas@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=1770735623; 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; bh=7x+sepqJzaiGguFJGDA2SGdYnfQz0dZUriOf1q/rtrY=; b=xvjbLyjUSL5ZOxwZC8E7fl/rkahjxryecLm6RP8kCdQZ9Pa6GN1fLTb6ekeI5wREUKDaSo 1pydEDLuJn1ahNBtHoRvEXtMsmaPSmr1Ru2NOI/3hgEF0i2l7fqhg3E+FpMIju8UHJzK/L jlyMbcEcSTPVOc+jpRwfHOExDYNfeFg= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=none; spf=pass (imf10.hostedemail.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770735623; a=rsa-sha256; cv=none; b=4Hwkcpovvwn7TvEh6HkpkbUQGRwFQ5eliFYP4sSyUpXL5Xdk6RUepZzsSgw1awPg3gXQ+f P49ymQomKFrzr6yEAVdJDuGX7qgCJwWsslRtbDjtu7FpUaNwhJUlt0L6UnGln2u09a6NEV +1oIWpDsSNOXs0HLBRBXWx1fvbwSlqo= 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 C3B86339; Tue, 10 Feb 2026 07:00:14 -0800 (PST) Received: from arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E8D253F63F; Tue, 10 Feb 2026 07:00:13 -0800 (PST) Date: Tue, 10 Feb 2026 15:00:11 +0000 From: Catalin Marinas To: Mike Rapoport Cc: Andrew Morton , Andreas Larsson , Borislav Petkov , Brian Cain , "Christophe Leroy (CS GROUP)" , "David S. Miller" , Dave Hansen , David Hildenbrand , Dinh Nguyen , Geert Uytterhoeven , Guo Ren , Helge Deller , Huacai Chen , Ingo Molnar , Johannes Berg , John Paul Adrian Glaubitz , "Liam R. Howlett" , Lorenzo Stoakes , Madhavan Srinivasan , Magnus Lindholm , Matt Turner , Max Filippov , Michael Ellerman , Michal Hocko , Michal Simek , Palmer Dabbelt , Richard Weinberger , Russell King , Stafford Horne , Suren Baghdasaryan , Thomas Gleixner , Vineet Gupta , Vlastimil Babka , Will Deacon , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org Subject: Re: [PATCH v2 3/4] arch, mm: consolidate empty_zero_page Message-ID: References: <20260209144058.2092871-1-rppt@kernel.org> <20260209144058.2092871-4-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260209144058.2092871-4-rppt@kernel.org> X-Stat-Signature: fptbafci7a5ugdmtgdpzmji4wwmsiq7o X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 67462C0019 X-HE-Tag: 1770735622-60893 X-HE-Meta: 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 sqFHWJWI XnJ4MU7Ub+M/+KPmFfvFJ7N1w8psrZSn8AlCdudwPgvVYMTzmHZXBzRqbsnAE5BCz5iu1L0Lhidm71CLb/z9nxsPQqOrVIOaVP3XcoYQexyDMUZImqPde8iCXSc1RxTDl7gm1G9BvHZJeb6fImE74eQHCgTDKCCcMD2C16kg293BdDkElfOwsMdkRRu1A48en5InoBj5DXgQa4ReieOM7x5u5uDfls4hjZdqgz1CTWrbyKv7Gn3xT0VEbOdWtutntZkMj1sdJB4pM70E= 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 Mon, Feb 09, 2026 at 04:40:56PM +0200, Mike Rapoport wrote: > From: "Mike Rapoport (Microsoft)" > > Reduce 22 declarations of empty_zero_page to 3 and 23 declarations of > ZERO_PAGE() to 4. > > Every architecture defines empty_zero_page that way or another, but for the > most of them it is always a page aligned page in BSS and most definitions > of ZERO_PAGE do virt_to_page(empty_zero_page). > > Move Linus vetted x86 definition of empty_zero_page and ZERO_PAGE() to the > core MM and drop these definitions in architectures that do not implement > colored zero page (MIPS and s390). > > ZERO_PAGE() remains a macro because turning it to a wrapper for a static > inline causes severe pain in header dependencies. > > For the most part the change is mechanical, with these being noteworthy: > > * alpha: aliased empty_zero_page with ZERO_PGE that was also used for boot > parameters. Switching to a generic empty_zero_page removes the aliasing > and keeps ZERO_PGE for boot parameters only > * arm64: uses __pa_symbol() in ZERO_PAGE() so that definition of > ZERO_PAGE() is kept intact. > * m68k/parisc/um: allocated empty_zero_page from memblock, > although they do not support zero page coloring and having it in BSS > will work fine. > * sparc64 can have empty_zero_page in BSS rather allocate it, but it > can't use virt_to_page() for BSS. Keep it's definition of ZERO_PAGE() > but instead of allocating it, make mem_map_zero point to > empty_zero_page. > * sh: used empty_zero_page for boot parameters at the very early boot. > Rename the parameters page to boot_params_page and let sh use the generic > empty_zero_page. > * hexagon: had an amusing comment about empty_zero_page > > /* A handy thing to have if one has the RAM. Declared in head.S */ > > that unfortunately had to go :) > > Acked-by: Helge Deller # parisc > Tested-by: Helge Deller # parisc > Reviewed-by: Christophe Leroy (CS GROUP) > Signed-off-by: Mike Rapoport (Microsoft) For arm64: Acked-by: Catalin Marinas