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 X-Spam-Level: X-Spam-Status: No, score=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1D782C433E0 for ; Fri, 29 Jan 2021 09:59:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 792B564E09 for ; Fri, 29 Jan 2021 09:59:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 792B564E09 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 82A266B0005; Fri, 29 Jan 2021 04:59:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7DFA46B0006; Fri, 29 Jan 2021 04:59:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6A6F36B006C; Fri, 29 Jan 2021 04:59:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0251.hostedemail.com [216.40.44.251]) by kanga.kvack.org (Postfix) with ESMTP id 356DA6B0005 for ; Fri, 29 Jan 2021 04:59:09 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id E5F1811806 for ; Fri, 29 Jan 2021 09:59:08 +0000 (UTC) X-FDA: 77758364376.25.blade63_2a0038d275a7 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id BF5651808F575 for ; Fri, 29 Jan 2021 09:59:08 +0000 (UTC) X-HE-Tag: blade63_2a0038d275a7 X-Filterd-Recvd-Size: 5901 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf11.hostedemail.com (Postfix) with ESMTP for ; Fri, 29 Jan 2021 09:59:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611914347; h=from:from: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=pQyKZtud72iNUCuIvr0ZIShBcdC/mmlf0peuy8Zc+LM=; b=IKHRKNalv25FjUmDP12n1etV4+AbXA3MjjN6chfSHIQYhh24JOjzoItBzseeNJGdim4jAS 2/Zsad14VhQ0ALvXklzZcbfqrrQvInGfDQShvaNV2q+MpVXx4jO6QjmILF/ndk0hv47Ys4 oRaYPE/6Lyi+dQmo8O+svQQo9lNynkQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-159-9Mm1trPcNMuUKaJM8Or7ww-1; Fri, 29 Jan 2021 04:59:05 -0500 X-MC-Unique: 9Mm1trPcNMuUKaJM8Or7ww-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 51EB29CC02; Fri, 29 Jan 2021 09:59:03 +0000 (UTC) Received: from [10.36.113.219] (ovpn-113-219.ams2.redhat.com [10.36.113.219]) by smtp.corp.redhat.com (Postfix) with ESMTP id 60F327771A; Fri, 29 Jan 2021 09:59:00 +0000 (UTC) Subject: Re: [PATCH 1/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory To: Anshuman Khandual , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Catalin Marinas , Will Deacon , Ard Biesheuvel , Mark Rutland , James Morse , Robin Murphy , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Dan Williams , Mike Rapoport References: <1611905986-20155-1-git-send-email-anshuman.khandual@arm.com> <1611905986-20155-2-git-send-email-anshuman.khandual@arm.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <31a1d742-843f-1837-8569-92b897190a81@redhat.com> Date: Fri, 29 Jan 2021 10:58:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <1611905986-20155-2-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 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 29.01.21 08:39, Anshuman Khandual wrote: > pfn_valid() validates a pfn but basically it checks for a valid struct page > backing for that pfn. It should always return positive for memory ranges > backed with struct page mapping. But currently pfn_valid() fails for all > ZONE_DEVICE based memory types even though they have struct page mapping. > > pfn_valid() asserts that there is a memblock entry for a given pfn without > MEMBLOCK_NOMAP flag being set. The problem with ZONE_DEVICE based memory is > that they do not have memblock entries. Hence memblock_is_map_memory() will > invariably fail via memblock_search() for a ZONE_DEVICE based address. This > eventually fails pfn_valid() which is wrong. memblock_is_map_memory() needs > to be skipped for such memory ranges. As ZONE_DEVICE memory gets hotplugged > into the system via memremap_pages() called from a driver, their respective > memory sections will not have SECTION_IS_EARLY set. > > Normal hotplug memory will never have MEMBLOCK_NOMAP set in their memblock > regions. Because the flag MEMBLOCK_NOMAP was specifically designed and set > for firmware reserved memory regions. memblock_is_map_memory() can just be > skipped as its always going to be positive and that will be an optimization > for the normal hotplug memory. Like ZONE_DEVICE based memory, all normal > hotplugged memory too will not have SECTION_IS_EARLY set for their sections > > Skipping memblock_is_map_memory() for all non early memory sections would > fix pfn_valid() problem for ZONE_DEVICE based memory and also improve its > performance for normal hotplug memory as well. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Ard Biesheuvel > Cc: Robin Murphy > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Fixes: 73b20c84d42d ("arm64: mm: implement pte_devmap support") > Signed-off-by: Anshuman Khandual > --- > arch/arm64/mm/init.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 709d98fea90c..1141075e4d53 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -230,6 +230,18 @@ int pfn_valid(unsigned long pfn) > > if (!valid_section(__pfn_to_section(pfn))) > return 0; > + > + /* > + * ZONE_DEVICE memory does not have the memblock entries. > + * memblock_is_map_memory() check for ZONE_DEVICE based > + * addresses will always fail. Even the normal hotplugged > + * memory will never have MEMBLOCK_NOMAP flag set in their > + * memblock entries. Skip memblock search for all non early > + * memory sections covering all of hotplug memory including > + * both normal and ZONE_DEVICE based. > + */ > + if (!early_section(__pfn_to_section(pfn))) > + return pfn_section_valid(__pfn_to_section(pfn), pfn); > #endif > return memblock_is_map_memory(addr); > } > LGTM Acked-by: David Hildenbrand -- Thanks, David / dhildenb