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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F90DC433F5 for ; Tue, 12 Oct 2021 17:31:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AFC1160EFE for ; Tue, 12 Oct 2021 17:31:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AFC1160EFE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 51942900004; Tue, 12 Oct 2021 13:31:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4C82D900002; Tue, 12 Oct 2021 13:31:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3B7D7900004; Tue, 12 Oct 2021 13:31:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0181.hostedemail.com [216.40.44.181]) by kanga.kvack.org (Postfix) with ESMTP id 2D6CC900002 for ; Tue, 12 Oct 2021 13:31:51 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id DF3D927DE3 for ; Tue, 12 Oct 2021 17:31:50 +0000 (UTC) X-FDA: 78688477980.22.9631E9E Received: from mail-pf1-f177.google.com (mail-pf1-f177.google.com [209.85.210.177]) by imf23.hostedemail.com (Postfix) with ESMTP id 950F590000BA for ; Tue, 12 Oct 2021 17:31:50 +0000 (UTC) Received: by mail-pf1-f177.google.com with SMTP id m14so152552pfc.9 for ; Tue, 12 Oct 2021 10:31:50 -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=pUEbToLkXzO64sMzwi8hZSFYRVuGFaFClCMCV1JpE/4=; b=FuafK/ST/MY15E3ZByuFdbwhEhPuiRWJQtQhsDDMAbRGZep2/+iILYUgLn0Z+LxJhL gUco/dBkSrN5/a3IPJuNMW/DZoAyaNGZhj6JMAKwOr71ZNxVW5pn+lc0XZ4hrbKrUGbx HO0ngdd9xD1X+nGHuxsQb+2OO4Xnw7OwZc/C8x0CcBnOiBrKmtiE7D1ifhUmD+memw7G mnoRAvXHlc8u1uW/0eHruND1Rk//SIwgunzWHq2h9h/ZMe/te8o+sAYBA/MbC/yrpz/2 5ulyN5+xA1f4z+59P++c2PieBpV1kvSSDEP56sDH1BID7pZhpahLbp3cVFtFVGdeARi5 qlEw== 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=pUEbToLkXzO64sMzwi8hZSFYRVuGFaFClCMCV1JpE/4=; b=36mvCpDcPujr89xclMbO6TOFPh9UNeqgaGHKB5jgYsK69aQqUM+HAPK5f6yaw21EWr gediRwembhf9M+5Vl8EqzQAQnf1nANHY8UNTFidkWDF+Ym7VzUhq+NzraDgILgjIKOkw CRt13UpxiOZoFWw5Y5fqEmjdiu8L/Eix+C787XJnO4AKZMslm+LhJdjlgGTy8xYdhFjN 5/+J1Y3v2nryr/66r9WhkhSwV5NR51xpviCTNzQTYGTom1Zg6VxOOQVUqZgLD8WZVZFy aE3/M6DKSrK9PfBIs6qpgPOjz47SAqlyOY3S6tJWj+vpo1EdXDcfYRoLcENeMXRyIa0K dKVA== X-Gm-Message-State: AOAM533lrY5Lb9prpaf1SRjw+JAU41PnnV0y1vlWzksNaLP/ROabl3IA Qcghhz55uTDUg/cEEpM/N94= X-Google-Smtp-Source: ABdhPJwXpmp/S4EF2gzYO6qNsdVEIT9OWiwycw7gt/wn++LKHsR/mPbzLTr51ZPTVzNj5pp3vki+CQ== X-Received: by 2002:aa7:9103:0:b0:44d:4d1d:6f36 with SMTP id 3-20020aa79103000000b0044d4d1d6f36mr1487780pfh.72.1634059909219; Tue, 12 Oct 2021 10:31:49 -0700 (PDT) Received: from smtpclient.apple (c-24-6-216-183.hsd1.ca.comcast.net. [24.6.216.183]) by smtp.gmail.com with ESMTPSA id 11sm11421880pfl.41.2021.10.12.10.31.46 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Oct 2021 10:31:48 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.13\)) Subject: Re: [PATCH 1/2] mm/mprotect: use mmu_gather From: Nadav Amit In-Reply-To: Date: Tue, 12 Oct 2021 10:31:45 -0700 Cc: Andrew Morton , LKML , Linux-MM , Andrea Arcangeli , Andrew Cooper , Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Gleixner , Will Deacon , Yu Zhao , Nick Piggin , x86@kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <2CED2F72-4D1C-4DBC-AC03-4B246E1673C2@gmail.com> References: <20210925205423.168858-1-namit@vmware.com> <20210925205423.168858-2-namit@vmware.com> To: Peter Xu X-Mailer: Apple Mail (2.3654.120.0.1.13) X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 950F590000BA X-Stat-Signature: dueqx9wwsgt3t8bz7rj54mhe4s1w4qk1 Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b="FuafK/ST"; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf23.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.210.177 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com X-HE-Tag: 1634059910-283754 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 Oct 12, 2021, at 3:16 AM, Peter Xu wrote: >=20 > On Sat, Sep 25, 2021 at 01:54:22PM -0700, Nadav Amit wrote: >> @@ -338,25 +344,25 @@ static unsigned long = change_protection_range(struct vm_area_struct *vma, >> struct mm_struct *mm =3D vma->vm_mm; >> pgd_t *pgd; >> unsigned long next; >> - unsigned long start =3D addr; >> unsigned long pages =3D 0; >> + struct mmu_gather tlb; >>=20 >> BUG_ON(addr >=3D end); >> pgd =3D pgd_offset(mm, addr); >> flush_cache_range(vma, addr, end); >> inc_tlb_flush_pending(mm); >> + tlb_gather_mmu(&tlb, mm); >> + tlb_start_vma(&tlb, vma); >=20 > Pure question: >=20 > I actually have no idea why tlb_start_vma() is needed here, as = protection range > can be just a single page, but anyway.. I do see that tlb_start_vma() = contains > a whole-vma flush_cache_range() when the arch needs it, then does it = mean that > besides the inc_tlb_flush_pending() to be dropped, so as to the other = call to > flush_cache_range() above? Good point. tlb_start_vma() and tlb_end_vma() are required since some archs do not batch TLB flushes across VMAs (e.g., ARM). I am not sure whether = that=E2=80=99s the best behavior for all archs, but I do not want to change it. Anyhow, you make a valid point that the flush_cache_range() should be dropped as well. I will do so for next version. Regards, Nadav=