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=-15.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 4B481C433DB for ; Fri, 5 Mar 2021 18:15:14 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B50AC650A3 for ; Fri, 5 Mar 2021 18:15:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B50AC650A3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zaVghv9qJ9vo+Hbub8wW/yEr5mGOWoDSQX9+KRCIhC8=; b=cXei6jiXhr6ffskr7bDAo+Be0 mA++kSgRbW2UNmjSu+eEaNTbzLHZWm+iHwRDfh6eFUT/a6d/lj4//tdSpawfrPH3FxiadzBWWmwC5 d/bzuC/hhvaWt3bzBZXajMzYFE3S1DbE9M8O0SzjAcCB9mVwNnAd4p7Ewwj/QxcO74yEkcw8V0iNd y2dqaRsE6g7zpVDNaib7SEBkL7lRVshGUrjCji4Qfms3f2lgGLxvdE5WHAkjJNIB8cizL3oqzZJdb 8hTaJ4DhHGTOA4m/ZXWw3VomNBKBFXr0JfF6t57GQUqB1C+mi8eSYi4RPP8IY0cLDpIxp5IOSZAX+ XarnvXvGA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lIExD-00FuYs-7X; Fri, 05 Mar 2021 18:13:35 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lIEx6-00FuXC-Ui for linux-arm-kernel@lists.infradead.org; Fri, 05 Mar 2021 18:13:32 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 67C1D6509B; Fri, 5 Mar 2021 18:13:25 +0000 (UTC) Date: Fri, 5 Mar 2021 18:13:23 +0000 From: Catalin Marinas To: Anshuman Khandual Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Will Deacon , Ard Biesheuvel , Mark Rutland , James Morse , Robin Murphy , =?iso-8859-1?B?Suly9G1l?= Glisse , Dan Williams , David Hildenbrand , Mike Rapoport , Veronika Kabatova Subject: Re: [PATCH V3 1/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Message-ID: <20210305181322.GI23855@arm.com> References: <1614921898-4099-1-git-send-email-anshuman.khandual@arm.com> <1614921898-4099-2-git-send-email-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1614921898-4099-2-git-send-email-anshuman.khandual@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210305_181329_935108_5D20B1BA X-CRM114-Status: GOOD ( 25.53 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Mar 05, 2021 at 10:54:57AM +0530, 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 > Acked-by: David Hildenbrand > 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 0ace5e68efba..5920c527845a 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); Would something like this work instead: if (online_device_section(ms)) return 1; to avoid the assumptions around early_section()? -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel