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 92C0DC05027 for ; Mon, 20 Feb 2023 15:55:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9FD336B0071; Mon, 20 Feb 2023 10:55:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 986B36B0072; Mon, 20 Feb 2023 10:55:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7FFFE6B0073; Mon, 20 Feb 2023 10:55:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 6C1E66B0071 for ; Mon, 20 Feb 2023 10:55:02 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 2A705C0882 for ; Mon, 20 Feb 2023 15:55:02 +0000 (UTC) X-FDA: 80488118844.06.BB2A88F Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf12.hostedemail.com (Postfix) with ESMTP id 72E0640019 for ; Mon, 20 Feb 2023 15:54:59 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none); spf=pass (imf12.hostedemail.com: domain of cmarinas@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=cmarinas@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1676908499; 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=GjAgm+DMsCoHLiPIjCFU15lhQszQNQTPCew618zHol4=; b=74z7wgX5Hx+ijwy8Os5CeleVMoR/adZCHc+CMpqJQogZo1XnBz9LyvYn8FkNVHIJu/73rw RJHMCpxjKgV2AdAkarsIKMtv8DF6kchqwwXb3Vb99Ebnz8e/DgCxPBw17Ppzgv580h8dBW pw/K0btOFoPpTpqxJf9tZqOWbfocjfY= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none); spf=pass (imf12.hostedemail.com: domain of cmarinas@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=cmarinas@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1676908499; a=rsa-sha256; cv=none; b=50u0e+EVNNkZjeIpwgh8V48OIA8NsieA1jodAyWH1n6aDzHbNLlnh+tS3SA1cGGchp4G76 nRk6gppWZBAiTgRuaLNOKnED44DNr7x9OZRncZn5DeQevCS/ULAAnPozBOiItnwSYleEP/ HvK8hrxNvjf14UcWTNUa/pwKFWuc64M= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 6F3E1B80B49; Mon, 20 Feb 2023 15:54:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83CD1C433D2; Mon, 20 Feb 2023 15:54:54 +0000 (UTC) Date: Mon, 20 Feb 2023 15:54:51 +0000 From: Catalin Marinas To: Peter Collingbourne Cc: andreyknvl@gmail.com, linux-mm@kvack.org, kasan-dev@googlegroups.com, ryabinin.a.a@gmail.com, linux-arm-kernel@lists.infradead.org, vincenzo.frascino@arm.com, will@kernel.org, eugenis@google.com Subject: Re: [PATCH v2] kasan: call clear_page with a match-all tag instead of changing page tag Message-ID: References: <20230216195924.3287772-1-pcc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230216195924.3287772-1-pcc@google.com> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 72E0640019 X-Stat-Signature: mjbextjymbf7bnoeqbcwp8pccmtqduij X-Rspam-User: X-HE-Tag: 1676908499-607894 X-HE-Meta: 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 gA1MQvFN 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 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: On Thu, Feb 16, 2023 at 11:59:24AM -0800, Peter Collingbourne wrote: > Instead of changing the page's tag solely in order to obtain a pointer > with a match-all tag and then changing it back again, just convert the > pointer that we get from kmap_atomic() into one with a match-all tag > before passing it to clear_page(). > > On a certain microarchitecture, this has been observed to cause a > measurable improvement in microbenchmark performance, presumably as a > result of being able to avoid the atomic operations on the page tag. > > Signed-off-by: Peter Collingbourne > Link: https://linux-review.googlesource.com/id/I0249822cc29097ca7a04ad48e8eb14871f80e711 Reviewed-by: Catalin Marinas Not sure how this will go upstream, maybe the mm tree? Otherwise happy to take it through the arm64 tree. Thanks. -- Catalin