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 591FEC46CD2 for ; Tue, 30 Jan 2024 08:20:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E13786B009B; Tue, 30 Jan 2024 03:20:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DC1ED6B00A1; Tue, 30 Jan 2024 03:20:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C89B86B00A2; Tue, 30 Jan 2024 03:20:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id B23D86B009B for ; Tue, 30 Jan 2024 03:20:09 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 8203340194 for ; Tue, 30 Jan 2024 08:20:09 +0000 (UTC) X-FDA: 81735279738.12.7FC67FA Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf15.hostedemail.com (Postfix) with ESMTP id BD9A1A000C for ; Tue, 30 Jan 2024 08:20:07 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=none; spf=pass (imf15.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@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=1706602807; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EIOZMV2UIx9GUUzIXttXCi4JPyWvi2IooZ1EY/5Ip28=; b=FLNFsinXslRUYNgf/x5fGwo7JUEib25E32/8up5zDeXNzEbEWwAw2gb5Sm8OzMjgMjQfmJ Mdp+oHafWZkgjztKc1oOv1Uxz+RMN20AJfVsALeRrfdtHNIARbgkgRT/Er9khwm/pZr4VK xIO2yEB+MSlSvjf/IqUklppLxKz6L9A= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=none; spf=pass (imf15.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1706602807; a=rsa-sha256; cv=none; b=ugzEN+H/PKNuip338RB3QPto/Etcm6s+iUOKbvFa6tJbq06PafQkYEtehwh88wg9LDowZB gyPg6HRGwbEubdSwCnjfB1NFaqAxt16HadTEjRDnegiuAnWFTbyrMrncoor4HuhkiA+0un uQqbySTmnDBdkde3EhHYtrPN5ZVtbNk= 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 923B3DA7; Tue, 30 Jan 2024 00:20:50 -0800 (PST) Received: from [10.57.79.54] (unknown [10.57.79.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D4FD33F738; Tue, 30 Jan 2024 00:20:03 -0800 (PST) Message-ID: <7d25f28f-67fe-4bb8-b686-61f4f96471e5@arm.com> Date: Tue, 30 Jan 2024 08:20:02 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/9] mm/memory: handle !page case in zap_present_pte() separately Content-Language: en-GB To: David Hildenbrand , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , Matthew Wilcox , Catalin Marinas , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , Michael Ellerman , Christophe Leroy , "Naveen N. Rao" , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org References: <20240129143221.263763-1-david@redhat.com> <20240129143221.263763-3-david@redhat.com> From: Ryan Roberts In-Reply-To: <20240129143221.263763-3-david@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: BD9A1A000C X-Rspam-User: X-Stat-Signature: rhop185b5gf8aozx5hyh1o1tsp4ww76s X-Rspamd-Server: rspam01 X-HE-Tag: 1706602807-679528 X-HE-Meta: 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 9jcsgcZu eYx+A1zU83TwUiBtSInbJrDXrM0Fwa8AEhu1QjQS+LJBIMexmajeW/nMubrzBXJ4cBc43QxkVBqI8ic8F7r3gK6vrGzfQ0po6CZfQF4JcPCPqYxKJKuUoEKGGvr9CkQZGUlEpZwp/QrGVNIsyPk1ptjQSoF/7p/e5+Ry5u+tignGB6zw8y8ZWegJPOI2IO62bzwiFXSudGaQXXWGfZx2c4rVfVhXQOhWEBQ1bu2MhYajdolGNkDWcUsUASgdWZL4Drf3oGbk9ZBwlqZ1s56AqNx2blfwShoaMf8X1GRMDrR1gIr1f8BCWh0+e9pNlbUM/OqrZ 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 29/01/2024 14:32, David Hildenbrand wrote: > We don't need uptodate accessed/dirty bits, so in theory we could > replace ptep_get_and_clear_full() by an optimized ptep_clear_full() > function. Let's rely on the provided pte. > > Further, there is no scenario where we would have to insert uffd-wp > markers when zapping something that is not a normal page (i.e., zeropage). > Add a sanity check to make sure this remains true. > > should_zap_folio() no longer has to handle NULL pointers. This change > replaces 2/3 "!page/!folio" checks by a single "!page" one. > > Signed-off-by: David Hildenbrand Reviewed-by: Ryan Roberts > --- > mm/memory.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 50a6c79c78fc..69502cdc0a7d 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1497,10 +1497,6 @@ static inline bool should_zap_folio(struct zap_details *details, > if (should_zap_cows(details)) > return true; > > - /* E.g. the caller passes NULL for the case of a zero folio */ > - if (!folio) > - return true; > - > /* Otherwise we should only zap non-anon folios */ > return !folio_test_anon(folio); > } > @@ -1543,19 +1539,23 @@ static inline void zap_present_pte(struct mmu_gather *tlb, > struct page *page; > > page = vm_normal_page(vma, addr, ptent); > - if (page) > - folio = page_folio(page); > + if (!page) { > + /* We don't need up-to-date accessed/dirty bits. */ > + ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); > + arch_check_zapped_pte(vma, ptent); > + tlb_remove_tlb_entry(tlb, pte, addr); > + VM_WARN_ON_ONCE(userfaultfd_wp(vma)); > + ksm_might_unmap_zero_page(mm, ptent); > + return; > + } > > + folio = page_folio(page); > if (unlikely(!should_zap_folio(details, folio))) > return; > ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); > arch_check_zapped_pte(vma, ptent); > tlb_remove_tlb_entry(tlb, pte, addr); > zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent); > - if (unlikely(!page)) { > - ksm_might_unmap_zero_page(mm, ptent); > - return; > - } > > if (!folio_test_anon(folio)) { > if (pte_dirty(ptent)) {