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[198.145.29.99]) by mx.google.com with ESMTPS id a1si1742318pjs.58.2019.07.31.09.10.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 31 Jul 2019 09:10:53 -0700 (PDT) Received-SPF: pass (google.com: domain of will@kernel.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=O0oO6ADu; spf=pass (google.com: domain of will@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=will@kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EDEF5206A3; Wed, 31 Jul 2019 16:10:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564589453; bh=WCCv3Aec470dqenJ3D0yJXfNnDANp7cVqdAtXPLEgsM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=O0oO6ADuBpn0GsCzed/V3vKsIofX8heKLLg1altER77SX8nvqgWsXXTEM1v+taPPH EIwclnx482U7aJLNBxzEszh8K/nBVMDE9WWJ3rSKcTQBSk8H0adilY4q0TaGfAK9h8 GAMdp9Q3T2fvoMqUn4p9KL2EwGx5PxfqoHpuEndc= Date: Wed, 31 Jul 2019 17:10:48 +0100 From: Will Deacon To: Anshuman Khandual Cc: linux-mm@kvack.org, Fenghua Yu , Tony Luck , linux-ia64@vger.kernel.org, Catalin Marinas , Dave Hansen , Will Deacon , x86@kernel.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Andrew Morton , linux-arm-kernel@lists.infradead.org Subject: Re: [RFC 1/2] mm/sparsemem: Add vmem_altmap support in vmemmap_populate_basepages() Message-ID: <20190731161047.ypye54x5c5jje5sq@willie-the-truck> References: <1561697083-7329-1-git-send-email-anshuman.khandual@arm.com> <1561697083-7329-2-git-send-email-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1561697083-7329-2-git-send-email-anshuman.khandual@arm.com> User-Agent: NeoMutt/20170113 (1.7.2) 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 Fri, Jun 28, 2019 at 10:14:42AM +0530, Anshuman Khandual wrote: > Generic vmemmap_populate_basepages() is used across platforms for vmemmap > as standard or as fallback when huge pages mapping fails. On arm64 it is > used for configs with ARM64_SWAPPER_USES_SECTION_MAPS applicable both for > ARM64_16K_PAGES and ARM64_64K_PAGES which cannot use huge pages because of > alignment requirements. > > This prevents those configs from allocating from device memory for vmemap > mapping as vmemmap_populate_basepages() does not support vmem_altmap. This > enables that required support. Each architecture should evaluate and decide > on enabling device based base page allocation when appropriate. Hence this > keeps it disabled for all architectures to preserve the existing semantics. This commit message doesn't really make sense to me. There's a huge amount of arm64-specific detail, followed by vague references to "this" and "those" and "that" and I lost track of what you're trying to solve. However, I puzzled through the code and I think it does make sense, so: Acked-by: Will Deacon assuming you rewrite the commit message. However, this has a dependency on your hot remove series which has open comments from Mark Rutland afaict. Will