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Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lZAgH-00CpOS-8N for linux-arm-kernel@lists.infradead.org; Wed, 21 Apr 2021 11:06:09 +0000 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 B0223113E; Wed, 21 Apr 2021 04:05:59 -0700 (PDT) Received: from [10.163.74.228] (unknown [10.163.74.228]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 678AC3F73B; Wed, 21 Apr 2021 04:05:55 -0700 (PDT) From: Anshuman Khandual Subject: Re: [PATCH v2 4/4] arm64: drop pfn_valid_within() and simplify pfn_valid() To: Mike Rapoport , linux-arm-kernel@lists.infradead.org Cc: 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> Message-ID: <66d50afe-77e6-70ee-6b51-5db28a086c68@arm.com> Date: Wed, 21 Apr 2021 16:36:46 +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: <20210421065108.1987-5-rppt@kernel.org> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210421_040605_414709_A906460D X-CRM114-Status: GOOD ( 29.93 ) 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 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. > } > EXPORT_SYMBOL(pfn_valid); > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel