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, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 61068C433B4 for ; Wed, 21 Apr 2021 13:15:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C56DF601FD for ; Wed, 21 Apr 2021 13:15:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C56DF601FD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 42D916B006C; Wed, 21 Apr 2021 09:15:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3F0DE6B006E; Wed, 21 Apr 2021 09:15:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 292826B0070; Wed, 21 Apr 2021 09:15:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0208.hostedemail.com [216.40.44.208]) by kanga.kvack.org (Postfix) with ESMTP id 0B6626B006C for ; Wed, 21 Apr 2021 09:15:08 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id B7D4C180AD81F for ; Wed, 21 Apr 2021 13:15:07 +0000 (UTC) X-FDA: 78056419854.20.5D0B0AA Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf01.hostedemail.com (Postfix) with ESMTP id 149C05001532 for ; Wed, 21 Apr 2021 13:15:04 +0000 (UTC) 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 99CBC11B3; Wed, 21 Apr 2021 06:15:06 -0700 (PDT) Received: from [192.168.0.130] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DB8C73F774; Wed, 21 Apr 2021 06:15:02 -0700 (PDT) Subject: Re: [PATCH v2 4/4] arm64: drop pfn_valid_within() and simplify pfn_valid() To: Mike Rapoport Cc: linux-arm-kernel@lists.infradead.org, Andrew Morton , Ard Biesheuvel , Catalin Marinas , David Hildenbrand , Marc Zyngier , Mark Rutland , Mike Rapoport , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20210421065108.1987-1-rppt@kernel.org> <20210421065108.1987-5-rppt@kernel.org> <66d50afe-77e6-70ee-6b51-5db28a086c68@arm.com> From: Anshuman Khandual Message-ID: Date: Wed, 21 Apr 2021 18:45:50 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 149C05001532 X-Stat-Signature: 1tn9g1qsudgqfg94qwtzxisstarq4gjj X-Rspamd-Server: rspam02 Received-SPF: none (arm.com>: No applicable sender policy available) receiver=imf01; identity=mailfrom; envelope-from=""; helo=foss.arm.com; client-ip=217.140.110.172 X-HE-DKIM-Result: none/none X-HE-Tag: 1619010904-287931 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 4/21/21 5:54 PM, Mike Rapoport wrote: > On Wed, Apr 21, 2021 at 04:36:46PM +0530, Anshuman Khandual wrote: >> >> On 4/21/21 12:21 PM, Mike Rapoport wrote: >>> From: Mike Rapoport >>> >>> The arm64's version of pfn_valid() differs from the generic because of two >>> reasons: >>> >>> * Parts of the memory map are freed during boot. This makes it necessary to >>> verify that there is actual physical memory that corresponds to a pfn >>> which is done by querying memblock. >>> >>> * There are NOMAP memory regions. These regions are not mapped in the >>> linear map and until the previous commit the struct pages representing >>> these areas had default values. >>> >>> As the consequence of absence of the special treatment of NOMAP regions in >>> the memory map it was necessary to use memblock_is_map_memory() in >>> pfn_valid() and to have pfn_valid_within() aliased to pfn_valid() so that >>> generic mm functionality would not treat a NOMAP page as a normal page. >>> >>> Since the NOMAP regions are now marked as PageReserved(), pfn walkers and >>> the rest of core mm will treat them as unusable memory and thus >>> pfn_valid_within() is no longer required at all and can be disabled by >>> removing CONFIG_HOLES_IN_ZONE on arm64. >> >> This makes sense. >> >>> >>> pfn_valid() can be slightly simplified by replacing >>> memblock_is_map_memory() with memblock_is_memory(). >>> >>> Signed-off-by: Mike Rapoport >>> --- >>> arch/arm64/Kconfig | 3 --- >>> arch/arm64/mm/init.c | 4 ++-- >>> 2 files changed, 2 insertions(+), 5 deletions(-) >>> >>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >>> index e4e1b6550115..58e439046d05 100644 >>> --- a/arch/arm64/Kconfig >>> +++ b/arch/arm64/Kconfig >>> @@ -1040,9 +1040,6 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK >>> def_bool y >>> depends on NUMA >>> >>> -config HOLES_IN_ZONE >>> - def_bool y >>> - >> >> Right. >> >>> source "kernel/Kconfig.hz" >>> >>> config ARCH_SPARSEMEM_ENABLE >>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >>> index dc03bdc12c0f..eb3f56fb8c7c 100644 >>> --- a/arch/arm64/mm/init.c >>> +++ b/arch/arm64/mm/init.c >>> @@ -243,7 +243,7 @@ int pfn_valid(unsigned long pfn) >>> >>> /* >>> * ZONE_DEVICE memory does not have the memblock entries. >>> - * memblock_is_map_memory() check for ZONE_DEVICE based >>> + * memblock_is_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 >>> @@ -254,7 +254,7 @@ int pfn_valid(unsigned long pfn) >>> return pfn_section_valid(ms, pfn); >>> } >>> #endif >>> - return memblock_is_map_memory(addr); >>> + return memblock_is_memory(addr); >> >> Wondering if MEMBLOCK_NOMAP is now being treated similarly to other >> memory pfns for page table walking purpose but with PageReserved(), >> why memblock_is_memory() is still required ? At this point, should >> not we just return valid for early_section() memory. As pfn_valid() >> now just implies that pfn has a struct page backing which has been >> already verified with valid_section() etc. > > memblock_is_memory() is required because arm64 frees unused parts of the > memory map. So, for instance, if we have 64M out of 128M populated in a > section the section based calculation would return 1 for a pfn in the > second half of the section, but there would be no memory map there. Understood.