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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2984C433F5 for ; Sun, 24 Apr 2022 16:04:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C3E686B0074; Sun, 24 Apr 2022 12:04:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BC6466B0075; Sun, 24 Apr 2022 12:04:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A412E6B0078; Sun, 24 Apr 2022 12:04:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 8DD0C6B0074 for ; Sun, 24 Apr 2022 12:04:58 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 611F51B7F for ; Sun, 24 Apr 2022 16:04:58 +0000 (UTC) X-FDA: 79392246276.13.F72C31C Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf01.hostedemail.com (Postfix) with ESMTP id 5B3CC40038 for ; Sun, 24 Apr 2022 16:04:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650816295; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=B2vstIxikfDjecSs+FgBZkRhZG01eDmdBK5EXWWYfDA=; b=Dn8Lx2ayKej9mEKJapOQMAXtLovSnDMYeafEIKWSitdhwXaVsHzh7fnvAnrzsyYy3a98Ao zjEudmMD+oOeNKmn5Fejr+hvP1+YbuSpnZjv6N7Hvc0iDC6Yb5Ix9idU5vcPOTRf9r9y3D tTJloB5qkYr133T/1mrI8F+3ljaPZoA= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-363-6qmN-6fjMTqGVD-Tfc7PQA-1; Sun, 24 Apr 2022 12:04:43 -0400 X-MC-Unique: 6qmN-6fjMTqGVD-Tfc7PQA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6A22F800882; Sun, 24 Apr 2022 16:04:41 +0000 (UTC) Received: from [10.22.16.111] (unknown [10.22.16.111]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9207840D017E; Sun, 24 Apr 2022 16:04:40 +0000 (UTC) Message-ID: Date: Sun, 24 Apr 2022 12:04:40 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [RFC PATCH] cgroup/cpuset: fix a memory binding failure for cgroup v2 Content-Language: en-US To: Tejun Heo , Feng Tang Cc: Zefan Li , Johannes Weiner , Andrew Morton , Michal Hocko , cgroups@vger.kernel.org, linux-mm@kvack.org, Dave Hansen , ying.huang@intel.com References: <20220419020958.40419-1-feng.tang@intel.com> From: Waiman Long In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 5B3CC40038 X-Stat-Signature: qb3iiz8rs7kna839xrremesa1dtsaf35 Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Dn8Lx2ay; spf=none (imf01.hostedemail.com: domain of longman@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=longman@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-HE-Tag: 1650816294-584267 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: On 4/21/22 18:22, Tejun Heo wrote: > cc'ing Waiman and copying the whole body. > > Waiman, can you please take a look? > > Thanks. > > On Tue, Apr 19, 2022 at 10:09:58AM +0800, Feng Tang wrote: >> We got report that setting cpuset.mems failed when the nodemask >> contains a newly onlined memory node (not enumerated during boot) >> for cgroup v2, while the binding succeeded for cgroup v1. >> >> The root cause is, for cgroup v2, when a new memory node is onlined, >> top_cpuset's 'mem_allowed' is not updated with the new nodemask of >> memory nodes, and the following setting memory nodemask will fail, >> if the nodemask contains a new node. >> >> Fix it by updating top_cpuset.mems_allowed right after the >> new memory node is onlined, just like v1. >> >> Signed-off-by: Feng Tang >> --- >> Very likely I missed some details here, but it looks strange that >> the top_cpuset.mem_allowed is not updatd even after we onlined >> several memory nodes after boot. >> >> kernel/cgroup/cpuset.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c >> index 9390bfd9f1cd..b97caaf16374 100644 >> --- a/kernel/cgroup/cpuset.c >> +++ b/kernel/cgroup/cpuset.c >> @@ -3314,8 +3314,7 @@ static void cpuset_hotplug_workfn(struct work_struct *work) >> /* synchronize mems_allowed to N_MEMORY */ >> if (mems_updated) { >> spin_lock_irq(&callback_lock); >> - if (!on_dfl) >> - top_cpuset.mems_allowed = new_mems; >> + top_cpuset.mems_allowed = new_mems; >> top_cpuset.effective_mems = new_mems; >> spin_unlock_irq(&callback_lock); >> update_tasks_nodemask(&top_cpuset); The on_dfl check was added by commit 7e88291beefb ("cpuset: make cs->{cpus, mems}_allowed as user-configured masks"). This is the expected behavior for cgroup v2 as we don't want to remove a node because it is hot-removed. However, I do see a problem in case we are adding a node that is not originally in top_cpuset.mems_allowed. We should be allowed to add the extra memory node. So something like         if (!on_dfl)                 top_cpuset.mems_allowed = new_mems;         else if (!nodes_subset(new_mems, top_cpuset.mems_allowed))                 nodes_or(top_cpuset.mems_allowed, top_cpuset.mems_allowed, new_mems); For v2, top_cpuset.mems_allowed is set to node_possible_map in cpuset_bind(). Perhaps node_possible_map may not include all the nodes that are hot-pluggable. I don't know if that is similar problem with cpu_possible_mask or not. Cheers, Longman