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Thu, 10 Sep 2020 07:51:39 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 47AC7A404D; Thu, 10 Sep 2020 07:51:39 +0000 (GMT) Received: from pomme.local (unknown [9.145.147.189]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 10 Sep 2020 07:51:39 +0000 (GMT) Subject: Re: [PATCH] mm: don't rely on system state to detect hot-plug operations To: Michal Hocko Cc: akpm@linux-foundation.org, David Hildenbrand , Oscar Salvador , rafael@kernel.org, nathanl@linux.ibm.com, cheloha@linux.ibm.com, stable@vger.kernel.org, Greg Kroah-Hartman , linux-mm@kvack.org, LKML References: <5cbd92e1-c00a-4253-0119-c872bfa0f2bc@redhat.com> <20200908170835.85440-1-ldufour@linux.ibm.com> <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> From: Laurent Dufour Message-ID: <31cfdf35-618f-6f56-ef16-0d999682ad02@linux.ibm.com> Date: Thu, 10 Sep 2020 09:51:39 +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: <20200910072331.GB28354@dhcp22.suse.cz> 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_01:2020-09-10,2020-09-10 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 malwarescore=0 mlxlogscore=999 priorityscore=1501 clxscore=1015 adultscore=0 suspectscore=0 phishscore=0 impostorscore=0 mlxscore=0 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009100065 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 10/09/2020 à 09:23, Michal Hocko a écrit : > On Wed 09-09-20 18:07:15, Laurent Dufour wrote: >> Le 09/09/2020 à 12:59, Michal Hocko a écrit : >>> On Wed 09-09-20 11:21:58, Laurent Dufour wrote: > [...] >>>> For the point a, using the enum allows to know in >>>> register_mem_sect_under_node() if the link operation is due to a hotplug >>>> operation or done at boot time. >>> >>> Yes, but let me repeat. We have a mess here and different paths check >>> for the very same condition by different ways. We need to unify those. >> >> What are you suggesting to unify these checks (using a MP_* enum as >> suggested by David, something else)? > > We do have system_state check spread at different places. I would use > this one and wrap it behind a helper. Or have I missed any reason why > that wouldn't work for this case? That would not work in that case because memory can be hot-added at the SYSTEM_SCHEDULING system state and the regular memory is also registered at that system state too. So system state is not enough to discriminate between the both. I think I'll go with the option suggested by David, replacing the enum memmap_context a new enum memplug_context and pass that context to register_mem_sect_under_node() so that function will known when node id should be checked or not. Cheers, Laurent.