From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 420DAC43461 for ; Thu, 10 Sep 2020 12:54:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 01DCE20882 for ; Thu, 10 Sep 2020 12:54:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730826AbgIJMxg (ORCPT ); Thu, 10 Sep 2020 08:53:36 -0400 Received: from mx2.suse.de ([195.135.220.15]:42112 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730740AbgIJMsu (ORCPT ); Thu, 10 Sep 2020 08:48:50 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 2BC9FACF2; Thu, 10 Sep 2020 12:49:04 +0000 (UTC) Date: Thu, 10 Sep 2020 14:48:47 +0200 From: Michal Hocko To: Oscar Salvador Cc: Laurent Dufour , akpm@linux-foundation.org, David Hildenbrand , rafael@kernel.org, nathanl@linux.ibm.com, cheloha@linux.ibm.com, stable@vger.kernel.org, Greg Kroah-Hartman , linux-mm@kvack.org, LKML Subject: Re: [PATCH] mm: don't rely on system state to detect hot-plug operations Message-ID: <20200910124847.GH28354@dhcp22.suse.cz> References: <20200909090953.GE7348@dhcp22.suse.cz> <4cdb54be-1a92-4ba4-6fee-3b415f3468a9@linux.ibm.com> <20200909105914.GF7348@dhcp22.suse.cz> <74a62b00-235e-7deb-2814-f3b240fea25e@linux.ibm.com> <20200910072331.GB28354@dhcp22.suse.cz> <31cfdf35-618f-6f56-ef16-0d999682ad02@linux.ibm.com> <20200910111246.GE28354@dhcp22.suse.cz> <20200910120343.GA6635@linux> <20200910124755.GG28354@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200910124755.GG28354@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 10-09-20 14:47:56, Michal Hocko wrote: > On Thu 10-09-20 14:03:48, Oscar Salvador wrote: > > On Thu, Sep 10, 2020 at 01:35:32PM +0200, Laurent Dufour wrote: > > > > > That points has been raised by David, quoting him here: > > > > > > > IIRC, ACPI can hotadd memory while SCHEDULING, this patch would break that. > > > > > > > > Ccing Oscar, I think he mentioned recently that this is the case with ACPI. > > > > > > Oscar told that he need to investigate further on that. > > > > I think my reply got lost. > > > > We can see acpi hotplugs during SYSTEM_SCHEDULING: > > > > $QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \ > > -m size=$MEM,slots=255,maxmem=4294967296k \ > > -numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \ > > -object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \ > > -object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \ > > -object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \ > > -object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \ > > -object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \ > > -object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \ > > -object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \ > > > > kernel: [ 0.753643] __add_memory: nid: 0 start: 0100000000 - 0108000000 (size: 134217728) > > kernel: [ 0.756950] register_mem_sect_under_node: system_state= 1 > > > > kernel: [ 0.760811] register_mem_sect_under_node+0x4f/0x230 > > kernel: [ 0.760811] walk_memory_blocks+0x80/0xc0 > > kernel: [ 0.760811] link_mem_sections+0x32/0x40 > > kernel: [ 0.760811] add_memory_resource+0x148/0x250 > > kernel: [ 0.760811] __add_memory+0x5b/0x90 > > kernel: [ 0.760811] acpi_memory_device_add+0x130/0x300 > > kernel: [ 0.760811] acpi_bus_attach+0x13c/0x1c0 > > kernel: [ 0.760811] acpi_bus_attach+0x60/0x1c0 > > kernel: [ 0.760811] acpi_bus_scan+0x33/0x70 > > kernel: [ 0.760811] acpi_scan_init+0xea/0x21b > > kernel: [ 0.760811] acpi_init+0x2f1/0x33c > > kernel: [ 0.760811] do_one_initcall+0x46/0x1f4 > > Is there any actual usecase for a configuration like this? What is the > point to statically define additional memory like this when the same can > be achieved on the same command line? Forgot to ask one more thing. Who is going to online that memory when userspace is not running yet? -- Michal Hocko SUSE Labs