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Thu, 10 Sep 2020 12:32:03 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2F2B4A4053; Thu, 10 Sep 2020 12:32:03 +0000 (GMT) Received: from pomme.local (unknown [9.145.147.189]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 10 Sep 2020 12:32:03 +0000 (GMT) Subject: Re: [PATCH] mm: don't rely on system state to detect hot-plug operations To: Oscar Salvador Cc: Michal Hocko , 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 References: <20200909074011.GD7348@dhcp22.suse.cz> <9faac1ce-c02d-7dbc-f79a-4aaaa5a73d28@linux.ibm.com> <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> From: Laurent Dufour Message-ID: <5104d47f-9b39-6f51-2cee-f2a153fab1df@linux.ibm.com> Date: Thu, 10 Sep 2020 14:32:02 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200910120343.GA6635@linux> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-09-10_03:2020-09-10,2020-09-10 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 clxscore=1015 priorityscore=1501 malwarescore=0 impostorscore=0 lowpriorityscore=0 bulkscore=0 suspectscore=0 phishscore=0 spamscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009100112 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 10/09/2020 à 14:03, Oscar Salvador a écrit : > 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 Thanks Oscar!