Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755050AbcLBDLz (ORCPT ); Thu, 1 Dec 2016 22:11:55 -0500 Received: from szxga01-in.huawei.com ([58.251.152.64]:7825 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234AbcLBDLy (ORCPT ); Thu, 1 Dec 2016 22:11:54 -0500 Message-ID: <5840E659.6000104@huawei.com> Date: Fri, 2 Dec 2016 11:11:21 +0800 From: Xishi Qiu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Scott Branden CC: Arnd Bergmann , Russell King , Catalin Marinas , Will Deacon , Ard Biesheuvel , Mark Rutland , , BCM Kernel Feedback , Tang Chen , , Subject: Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support References: <1480637999-4320-1-git-send-email-scott.branden@broadcom.com> <5840D333.9050801@huawei.com> <9cfa95ca-a9e9-299d-d020-7e565562dcf5@broadcom.com> In-Reply-To: <9cfa95ca-a9e9-299d-d020-7e565562dcf5@broadcom.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.25.179] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3543 Lines: 116 On 2016/12/2 10:38, Scott Branden wrote: > Hi Xishi, > > Thanks for the reply - please see comments below. > > On 16-12-01 05:49 PM, Xishi Qiu wrote: >> On 2016/12/2 8:19, Scott Branden wrote: >> >>> This patchset is sent for comment to add memory hotplug support for ARM64 >>> based platforms. It follows hotplug code added for other architectures >>> in the linux kernel. >>> >>> I tried testing the memory hotplug feature following documentation from >>> Documentation/memory-hotplug.txt. I don't think it is working as expected >>> - see below: >>> >>> To add memory to the system I did the following: >>> echo 0x400000000 > /sys/devices/system/memory/probe >>> >>> The memory is displayed as system ram: >>> cat /proc/iomem: >>> 74000000-77ffffff : System RAM >>> 74080000-748dffff : Kernel code >>> 74950000-749d2fff : Kernel data >>> 400000000-43fffffff : System RAM >>> >>> But does not seem to be added to the kernel memory. >>> /proc/meminfo did not change. >>> >>> What else needs to be done so the memory is added to the kernel memory >>> pool for normal allocation? >>> >> >> Hi Scott, >> >> Do you mean it still don't support hod-add after apply this patchset? > > After applying the patch it appears to partially support hot-add. Please let me know if you think it is working as expected? > > The memory probe functions in that the memory is registered with the system and shows up in /proc/iomem. But, the memory is not available in /proc/meminfo. Do you think something else needs to be adjusted for ARM64 to hotadd the memory > > I just found another clue: > under /sys/devices/system/memory I only see one memory entry (before or after I try to hotadd additional memory). > > /sys/devices/system/memory # ls > auto_online_blocks memory0 uevent > block_size_bytes probe > > In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 28 and recompile I get the following: > /sys/devices/system/memory # ls > auto_online_blocks memory7 uevent > block_size_bytes probe > > > In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 27 and recompile I get the following: > /sys/devices/system/memory # ls > auto_online_blocks memory14 uevent > block_size_bytes probe > > If looks to me like something is not working properly in the ARM64 implementation. I should expect to see multiple memoryX entries under /sys/devices/system/memory? > Hi Scott, 1. Do you enable the following configs? CONFIG_SPARSEMEM MEMORY_HOTPLUG CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE 2. I find you missed create mapping in arch_add_memory(), and x86 has it. 3. We will add memblock first, so pfn_valid() maybe always return true(in the following function), and this will lead __add_section() failed. Please check it. int pfn_valid(unsigned long pfn) { return (pfn & PFN_MASK) == pfn && memblock_is_memory(pfn << PAGE_SHIFT); } add_memory add_memory_resource memblock_add_node arch_add_memory __add_pages __add_section pfn_valid Thanks, Xishi Qiu > > >> >> Thanks, >> Xishi Qiu >> >>> Scott Branden (2): >>> arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE, >>> MEMORY_PROBE >>> arm64: defconfig: enable MEMORY_HOTPLUG config options >>> >>> arch/arm64/Kconfig | 10 ++++++++++ >>> arch/arm64/configs/defconfig | 3 +++ >>> arch/arm64/mm/init.c | 42 ++++++++++++++++++++++++++++++++++++++++++ >>> 3 files changed, 55 insertions(+) >>> >> >> >> > > . >