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 353A1C433EF for ; Mon, 25 Oct 2021 16:29:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AAEA260F92 for ; Mon, 25 Oct 2021 16:29:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AAEA260F92 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 37D72940009; Mon, 25 Oct 2021 12:29:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 32CE5940008; Mon, 25 Oct 2021 12:29:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 21C1D940009; Mon, 25 Oct 2021 12:29:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0147.hostedemail.com [216.40.44.147]) by kanga.kvack.org (Postfix) with ESMTP id 14631940008 for ; Mon, 25 Oct 2021 12:29:14 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id B5A231802DDEE for ; Mon, 25 Oct 2021 16:29:13 +0000 (UTC) X-FDA: 78735494586.08.8FA8D92 Received: from mail-pg1-f169.google.com (mail-pg1-f169.google.com [209.85.215.169]) by imf19.hostedemail.com (Postfix) with ESMTP id 2D550B0000A3 for ; Mon, 25 Oct 2021 16:29:09 +0000 (UTC) Received: by mail-pg1-f169.google.com with SMTP id r28so7125387pga.0 for ; Mon, 25 Oct 2021 09:29:13 -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=g/bHWNbEVTUu1p1pY3zhFaw/B4nH/Dtxkz7BbwLJ14U=; b=aaaJn8CeCvh2LyKQmHk811Z9LqBaCi8WSPoU+cUqJghexKlravjNGfOOPb8ssVCCAX LwjqULdEu/3SYG7DlaswU9DD8m4LPHy9SCRh28KbqUFkVu/Xhxd1ISDw4Qb6uo9VoI7D jc5CSwlbCKJLhLKdVddBFpskz5Sa08QlKNyiiiGL6E7F/cWxTZa3ist4cLyR129HIZ6u cE+VolALQkWNdzM7Y6zfWLEwLPGmeqPSi0fhgZNSU69618ZdCutkVPjod/CHdqBIXmPr XDjAG9MPPCO4jGAQTSCkaD67ke8TpkR0gnKS0GSNER6NoKI82P+z+RFBTcc8eio8qykI Y84w== 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=g/bHWNbEVTUu1p1pY3zhFaw/B4nH/Dtxkz7BbwLJ14U=; b=6bMuoj21JdfdoKQbO1xWiik6mvdpVnWwOaWMYZVrgKWfWEQkStYNHMVnbs2XTm7V4z 96SxmPWtgBaC0john/QlYHiLwQ/B81xrU1amXuMEEY0+8jvVN5Ag7SKUPQyBDAzjP3V1 O+tpb/2O5lTqatJsPHwtZnSX1huxhREC3T2fqy3IvXObEX9K+ogilh4s6xZBD5FX8ILO 48l4rM9LcDattjoEH6e3ZZX9b6CzeHLucaPKpX71MpfdM9oteh4+sba6Q3vmKuSvboh7 RHC6eFK0OiAycoAQZtY8RuLG4ud/YoFtfTc68H/oMMusHLzU3HB73Bs/6xpuHL2utJgi V0jg== X-Gm-Message-State: AOAM5339YxnbEn66/AbsIaGx6Td3TJGE64hLPr5FpnBUUPgW3B42jD26 ++ndpXEm3bg+dmziK4ng2TE= X-Google-Smtp-Source: ABdhPJxolYbehxB+mzV13Kboc6Y9AiTm0yykP/kkPo0UxWNJC43oVo/DFlNrgmd3/JxDpsQMHng7HA== X-Received: by 2002:a05:6a00:b85:b0:47b:ff97:841e with SMTP id g5-20020a056a000b8500b0047bff97841emr3612045pfj.48.1635179352143; Mon, 25 Oct 2021 09:29:12 -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 s3sm22337446pfu.84.2021.10.25.09.29.11 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 25 Oct 2021 09:29:11 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.13\)) Subject: Re: [PATCH v2 2/5] mm: avoid unnecessary flush on change_huge_pmd() From: Nadav Amit In-Reply-To: Date: Mon, 25 Oct 2021 09:29:09 -0700 Cc: Linux-MM , LKML , Andrea Arcangeli , Andrew Cooper , Andrew Morton , Andy Lutomirski , Dave Hansen , Peter Xu , Thomas Gleixner , Will Deacon , Yu Zhao , Nick Piggin , x86@kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20211021122112.592634-1-namit@vmware.com> <20211021122112.592634-3-namit@vmware.com> To: Peter Zijlstra X-Mailer: Apple Mail (2.3654.120.0.1.13) X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 2D550B0000A3 X-Stat-Signature: qhy1x9cjofkxiy3u3gwwd15er44bqfzb Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=aaaJn8Ce; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf19.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.215.169 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com X-HE-Tag: 1635179349-780497 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 25, 2021, at 3:52 AM, Peter Zijlstra = wrote: >=20 > On Thu, Oct 21, 2021 at 05:21:09AM -0700, Nadav Amit wrote: >> diff --git a/arch/x86/include/asm/pgtable.h = b/arch/x86/include/asm/pgtable.h >> index 448cd01eb3ec..18c3366f8f4d 100644 >> --- a/arch/x86/include/asm/pgtable.h >> +++ b/arch/x86/include/asm/pgtable.h >> @@ -1146,6 +1146,14 @@ static inline pmd_t pmdp_establish(struct = vm_area_struct *vma, >> } >> } >> #endif >> + >> +#define __HAVE_ARCH_PMDP_INVALIDATE_AD >> +static inline pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, >> + unsigned long address, pmd_t = *pmdp) >> +{ >> + return pmdp_establish(vma, address, pmdp, pmd_mkinvalid(*pmdp)); >=20 > Did this want to be something like: >=20 > pmd_t old =3D pmdp_establish(vma, address, pmdp, = pmd_mkinvalid(*pmdp)); > if (cpu_feature_enabled(X86_BUG_PTE_LEAK)) > flush_pmd_tlb_range(vma, address, address + = HPAGE_PMD_SIZE); > return old; >=20 > instead? Yes. Of course. Where did my code go to? :( >=20 >> +} >> + >> /* >> * Page table pages are page-aligned. The lower half of the top >> * level is used for userspace and the top half for the kernel. >=20 >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index e5ea5f775d5c..435da011b1a2 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -1795,10 +1795,11 @@ int change_huge_pmd(struct vm_area_struct = *vma, pmd_t *pmd, >> * The race makes MADV_DONTNEED miss the huge pmd and don't = clear it >> * which may break userspace. >> * >> - * pmdp_invalidate() is required to make sure we don't miss >> - * dirty/young flags set by hardware. >> + * pmdp_invalidate_ad() is required to make sure we don't miss >> + * dirty/young flags (which are also known as access/dirty) = cannot be >> + * further modifeid by the hardware. >=20 > "modified", I think is the more common spelling. I tried to start a new trend. I will fix it. >=20 >> */ >> - entry =3D pmdp_invalidate(vma, addr, pmd); >> + entry =3D pmdp_invalidate_ad(vma, addr, pmd); >>=20 >> entry =3D pmd_modify(entry, newprot); >> if (preserve_write) >> diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c >> index 4e640baf9794..b0ce6c7391bf 100644 >> --- a/mm/pgtable-generic.c >> +++ b/mm/pgtable-generic.c >> @@ -200,6 +200,14 @@ pmd_t pmdp_invalidate(struct vm_area_struct = *vma, unsigned long address, >> } >> #endif >>=20 >> +#ifndef __HAVE_ARCH_PMDP_INVALIDATE_AD >=20 > /* > * Does this deserve a comment to explain the intended difference vs > * pmdp_invalidate() ? > */ I will add a comment.