From patchwork Wed Jul 29 03:34:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia He X-Patchwork-Id: 11690301 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C5F9A1575 for ; Wed, 29 Jul 2020 03:36:49 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 9B52220786 for ; Wed, 29 Jul 2020 03:36:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="PIYJIUm7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B52220786 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Owner; bh=Qjjj7aTBtI9k+acs4J0JUfkSKNjAW+rInciCIKCR/TY=; b=PIYJIUm7NZHr7OiuX+hl5zJ3bB ifBut37wp4q9TPGmqumKOoXf8SP0kaB67bStDZAFqF11sJcG9zMZKNMsTYucTGFti9+F5IMiVwHYQ evFLXQr2c7wir6Jih4vojXR9ltHevxK9YUiiLqkC+uGPIgYL/UV98SVtXrMmVIdTWhsE+LypQCNT7 AJVVOsDK1WtygXIUzFr2bSOdiMLaWyg1c+pnMbKdCU4PiA5GOSnAeKRA3sGQaz2mDt3PUuY79Uz4S tUhEecvjRmT2wc/HH1CCCXm048XlkZk6DT9zSUhYUf1VqK/XHxDAk2BhgUfbOJeVE1wNIgck5eq+x OXRn5S6A==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0csB-0002Lt-L2; Wed, 29 Jul 2020 03:35:19 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0cs9-0002Kx-2z for linux-arm-kernel@lists.infradead.org; Wed, 29 Jul 2020 03:35:18 +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 309D631B; Tue, 28 Jul 2020 20:35:12 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.212.213]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A94CC3F66E; Tue, 28 Jul 2020 20:35:04 -0700 (PDT) From: Jia He To: Dan Williams , Vishal Verma , Mike Rapoport , David Hildenbrand Subject: [RFC PATCH 0/6] decrease unnecessary gap due to pmem kmem alignment Date: Wed, 29 Jul 2020 11:34:18 +0800 Message-Id: <20200729033424.2629-1-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200728_233517_255665_7AB4075B X-CRM114-Status: GOOD ( 13.86 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [217.140.110.172 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , "Rafael J. Wysocki" , Catalin Marinas , Dave Hansen , linux-mm@kvack.org, Ira Weiny , Dave Jiang , Jason Gunthorpe , Will Deacon , Kaly Xin , Kees Cook , Anshuman Khandual , Hsin-Yi Wang , Jia He , linux-arm-kernel@lists.infradead.org, Pankaj Gupta , Steve Capper , Greg Kroah-Hartman , linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, Wei Yang , Andrew Morton , Logan Gunthorpe MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org When enabling dax pmem as RAM device on arm64, I noticed that kmem_start addr in dev_dax_kmem_probe() should be aligned w/ SECTION_SIZE_BITS(30),i.e. 1G memblock size. Even Dan Williams' sub-section patch series [1] had been upstream merged, it was not helpful due to hard limitation of kmem_start: $ndctl create-namespace -e namespace0.0 --mode=devdax --map=dev -s 2g -f -a 2M $echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind $echo dax0.0 > /sys/bus/dax/drivers/kmem/new_id $cat /proc/iomem ... 23c000000-23fffffff : System RAM 23dd40000-23fecffff : reserved 23fed0000-23fffffff : reserved 240000000-33fdfffff : Persistent Memory 240000000-2403fffff : namespace0.0 280000000-2bfffffff : dax0.0 <- aligned with 1G boundary 280000000-2bfffffff : System RAM Hence there is a big gap between 0x2403fffff and 0x280000000 due to the 1G alignment. Without this series, if qemu creates a 4G bytes nvdimm device, we can only use 2G bytes for dax pmem(kmem) in the worst case. e.g. 240000000-33fdfffff : Persistent Memory We can only use the memblock between [240000000, 2ffffffff] due to the hard limitation. It wastes too much memory space. Decreasing the SECTION_SIZE_BITS on arm64 might be an alternative, but there are too many concerns from other constraints, e.g. PAGE_SIZE, hugetlb, SPARSEMEM_VMEMMAP, page bits in struct page ... Beside decreasing the SECTION_SIZE_BITS, we can also relax the kmem alignment with memory_block_size_bytes(). Tested on arm64 guest and x86 guest, qemu creates a 4G pmem device. dax pmem can be used as ram with smaller gap. Also the kmem hotplug add/remove are both tested on arm64/x86 guest. This patch series (mainly patch6/6) is based on the fixing patch, ~v5.8-rc5 [2]. [1] https://lkml.org/lkml/2019/6/19/67 [2] https://lkml.org/lkml/2020/7/8/1546 Jia He (6): mm/memory_hotplug: remove redundant memory block size alignment check resource: export find_next_iomem_res() helper mm/memory_hotplug: allow pmem kmem not to align with memory_block_size mm/page_alloc: adjust the start,end in dax pmem kmem case device-dax: relax the memblock size alignment for kmem_start arm64: fall back to vmemmap_populate_basepages if not aligned with PMD_SIZE arch/arm64/mm/mmu.c | 4 ++++ drivers/base/memory.c | 24 ++++++++++++++++-------- drivers/dax/kmem.c | 22 +++++++++++++--------- include/linux/ioport.h | 3 +++ kernel/resource.c | 3 ++- mm/memory_hotplug.c | 39 ++++++++++++++++++++++++++++++++++++++- mm/page_alloc.c | 14 ++++++++++++++ 7 files changed, 90 insertions(+), 19 deletions(-)