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 DFBA3C433EF for ; Wed, 23 Mar 2022 22:10:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 668FC6B0072; Wed, 23 Mar 2022 18:10:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6198B6B0073; Wed, 23 Mar 2022 18:10:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4B9756B0074; Wed, 23 Mar 2022 18:10:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0061.hostedemail.com [216.40.44.61]) by kanga.kvack.org (Postfix) with ESMTP id 399366B0072 for ; Wed, 23 Mar 2022 18:10:03 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id DA19D180A62E9 for ; Wed, 23 Mar 2022 22:10:02 +0000 (UTC) X-FDA: 79277044644.29.A82C712 Received: from mail-pg1-f178.google.com (mail-pg1-f178.google.com [209.85.215.178]) by imf15.hostedemail.com (Postfix) with ESMTP id 8C941A002D for ; Wed, 23 Mar 2022 22:10:02 +0000 (UTC) Received: by mail-pg1-f178.google.com with SMTP id bc27so2314223pgb.4 for ; Wed, 23 Mar 2022 15:10:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=yBaJs7MenreJBlH0zpoMDEAFvI+zts6CaxJbclE6otQ=; b=nuilKwYQPusXhRvoB2Vr4s5NnzspkIpj8fOQnK4tVJ01JUbVSuApjKBR3dTxlvTxNG OmKRGBDRX1pImXrW2Pq1QbCXAdRm0b1ye/e92mhf/qcV+RPFbVu5+iHhq1ym/TGziQer QfViAWyosCTbIl6OmHVKaMyX91db3hWhdjPYR+kI42dXrZK0PoEX2kaQnJ1QojJxgtS8 ifFi7Dg3O18G4SbizTbJUiouU/DuILuvgFXaf5ACyPTFrKJVXFExeDnN/bWPTbl7YU2Y dUI7G8GXKquXrUfwd0kpDt54k5IYAQLArspAFuvNyhWOFsOOhTuDHt639Nbkswz4d99G pq8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=yBaJs7MenreJBlH0zpoMDEAFvI+zts6CaxJbclE6otQ=; b=o3Z2CvFSr5dN6rZ/MlbJ+X5MrTRNh4BARrF5v5nhj0jCVqj81P6arTwH7NtAJVrvHh +g7qVLwWSxNDQxGrkJA0GWknrsaFrH80Ehem12Uqwkatya4x+VikYH+kqocqMyfxCGJP MKeaqPHoJgBnYzEiXBrkuztSNWMbSTfm3x/xtcpeIlTDvXik2kgR7ZBHHPJyUfxo92Y/ o8SHZz7MM5wKhCqZO51AFDTGazl8fGPVH5zqbaWRzqkf2KJdLw7axTheY/ZCzwRM1Xsz EXeE+w3P7mkGRiv/sdBcDegFpMdolHNUx5fnotZyLrWiBzR1xwBO4bjueixWPxy3+ZNh uQbg== X-Gm-Message-State: AOAM533DHQ3sx5hbChnU+0d4QEtSg/9PS5mqMl/aKpycjmuSUxnBJpV7 vOVU93ODA4hL2fomZUK3I0s= X-Google-Smtp-Source: ABdhPJwIRZWyd4UfCi2tFCXRIxhTZoAypmWW8Dn7v/BMtOCT7Dp8oSR2+UZ07oQuI4ppROIYePvAxQ== X-Received: by 2002:a63:1849:0:b0:380:3aee:496a with SMTP id 9-20020a631849000000b003803aee496amr1494834pgy.489.1648073401066; Wed, 23 Mar 2022 15:10:01 -0700 (PDT) Received: from smtpclient.apple ([66.170.99.2]) by smtp.gmail.com with ESMTPSA id k14-20020a056a00134e00b004f83f05608esm818546pfu.31.2022.03.23.15.09.59 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 Mar 2022 15:10:00 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.80.82.1.1\)) Subject: Re: [RESEND PATCH v5 2/3] mm/mprotect: do not flush when not required architecturally From: Nadav Amit In-Reply-To: <20220320000719.1533862-3-namit@vmware.com> Date: Wed, 23 Mar 2022 15:09:58 -0700 Cc: linux-mm , Andrea Arcangeli , Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Gleixner , Will Deacon , Yu Zhao , Nick Piggin , x86@kernel.org Content-Transfer-Encoding: 7bit Message-Id: <7CAC2587-6C39-4286-9DED-5FC8588B5513@gmail.com> References: <20220320000719.1533862-1-namit@vmware.com> <20220320000719.1533862-3-namit@vmware.com> To: Andrew Morton X-Mailer: Apple Mail (2.3696.80.82.1.1) X-Rspam-User: Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=nuilKwYQ; spf=pass (imf15.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.215.178 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 8C941A002D X-Stat-Signature: wuh5ji9o75kgwb8i5t78t4rifir4axop X-HE-Tag: 1648073402-201241 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 Mar 19, 2022, at 5:07 PM, Nadav Amit wrote: > > From: Nadav Amit > > Currently, using mprotect() to unprotect a memory region or uffd to > unprotect a memory region causes a TLB flush. However, in such cases the > PTE is often not modified (i.e., remain RO) and therefore not TLB flush > is needed. > > Add an arch-specific pte_needs_flush() which tells whether a TLB flush > is needed based on the old PTE and the new one. Implement an x86 > pte_needs_flush(). > > Always flush the TLB when it is architecturally needed even when > skipping a TLB flush might only result in a spurious page-faults by > skipping the flush. Errr.. Sent the wrong version. Will resend with new version number.