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: 11690269 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 DDA7A1575 for ; Wed, 29 Jul 2020 03:35:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A236A20786 for ; Wed, 29 Jul 2020 03:35:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A236A20786 Authentication-Results: mail.kernel.org; dmarc=none (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 9776A8D0002; Tue, 28 Jul 2020 23:35:14 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 927E16B002C; Tue, 28 Jul 2020 23:35:14 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 83CFA8D0002; Tue, 28 Jul 2020 23:35:14 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0177.hostedemail.com [216.40.44.177]) by kanga.kvack.org (Postfix) with ESMTP id 6C3926B002B for ; Tue, 28 Jul 2020 23:35:14 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 3325C180AD804 for ; Wed, 29 Jul 2020 03:35:14 +0000 (UTC) X-FDA: 77089697748.27.gun53_1c139e226f6f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin27.hostedemail.com (Postfix) with ESMTP id F1FCE6D688D for ; Wed, 29 Jul 2020 03:35:13 +0000 (UTC) X-Spam-Summary: 50,0,0,77b266b05d61aee8,d41d8cd98f00b204,justin.he@arm.com,,RULES_HIT:41:355:379:541:960:967:968:973:988:989:1260:1261:1345:1437:1534:1542:1711:1730:1747:1777:1792:2393:2525:2561:2564:2682:2685:2859:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3354:3653:3865:3866:3867:3868:3870:3871:3872:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4250:4321:4605:5007:6120:6261:6742:6743:7875:8603:8634:9025:10004:11026:11473:11657:11658:11914:12043:12048:12291:12296:12297:12438:12555:12679:12683:12895:12986:14096:14181:14721:21067:21080:21324:21451:21627:21788:30054:30070,0,RBL:217.140.110.172:@arm.com:.lbl8.mailshell.net-64.201.201.201 62.14.0.100;04yfqddut8aconf3ke8gn16c1kjjeocswrre4xif45tsf383q4pnh7z3iirin9n.hw5yaw4qcch4k6s4tmmutcnwdkiafmijpdpsodk1s8tc97zpq3fgx1awsqyax5i.e-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:24,LU A_SUMMAR X-HE-Tag: gun53_1c139e226f6f X-Filterd-Recvd-Size: 4537 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Wed, 29 Jul 2020 03:35:13 +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 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 Cc: Catalin Marinas , Will Deacon , Greg Kroah-Hartman , "Rafael J. Wysocki" , Dave Jiang , Andrew Morton , Steve Capper , Mark Rutland , Logan Gunthorpe , Anshuman Khandual , Hsin-Yi Wang , Jason Gunthorpe , Dave Hansen , Kees Cook , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-mm@kvack.org, Wei Yang , Pankaj Gupta , Ira Weiny , Kaly Xin , Jia He 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-Rspamd-Queue-Id: F1FCE6D688D X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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: 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(-)