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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 7E452C3A5A2 for ; Tue, 10 Sep 2019 12:53:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4F2C120863 for ; Tue, 10 Sep 2019 12:53:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568120024; bh=z5rsMlNBWBVt1XjnIJ7MFPDPOclpdloP3D9XosYHE7A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ZNCX4U/tpeil2v2bqTIUxTXj+3+XPvTFep/u4a39SVayOmYwwsv2NwB8hyOGc0Ai5 l+9YJSxFZzvHKO5ULxnXyoMmR4cwhkT9+GZ/ilOq2HqttKVkhwVhy6VoQOQxdjx9pe URiFdKnhA2H1Lu/lgRx6/N1pVkSrDfe86MMRIfmI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390761AbfIJMxn (ORCPT ); Tue, 10 Sep 2019 08:53:43 -0400 Received: from mx2.suse.de ([195.135.220.15]:46410 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729140AbfIJMxn (ORCPT ); Tue, 10 Sep 2019 08:53:43 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A7C16AFCD; Tue, 10 Sep 2019 12:53:40 +0000 (UTC) Date: Tue, 10 Sep 2019 14:53:39 +0200 From: Michal Hocko To: Yunsheng Lin Cc: Greg KH , rafael@kernel.org, linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@kernel.org, linuxarm@huawei.com Subject: Re: [PATCH] driver core: ensure a device has valid node id in device_add() Message-ID: <20190910125339.GZ2063@dhcp22.suse.cz> References: <1568009063-77714-1-git-send-email-linyunsheng@huawei.com> <20190909095347.GB6314@kroah.com> <9598b359-ab96-7d61-687a-917bee7a5cd9@huawei.com> <20190910093114.GA19821@kroah.com> <34feca56-c95e-41a6-e09f-8fc2d2fd2bce@huawei.com> <20190910110451.GP2063@dhcp22.suse.cz> <20190910111252.GA8970@kroah.com> <5a5645d2-030f-7921-432f-ff7d657405b8@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5a5645d2-030f-7921-432f-ff7d657405b8@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 10-09-19 20:47:40, Yunsheng Lin wrote: > On 2019/9/10 19:12, Greg KH wrote: > > On Tue, Sep 10, 2019 at 01:04:51PM +0200, Michal Hocko wrote: > >> On Tue 10-09-19 18:58:05, Yunsheng Lin wrote: > >>> On 2019/9/10 17:31, Greg KH wrote: > >>>> On Tue, Sep 10, 2019 at 02:43:32PM +0800, Yunsheng Lin wrote: > >>>>> On 2019/9/9 17:53, Greg KH wrote: > >>>>>> On Mon, Sep 09, 2019 at 02:04:23PM +0800, Yunsheng Lin wrote: > >>>>>>> Currently a device does not belong to any of the numa nodes > >>>>>>> (dev->numa_node is NUMA_NO_NODE) when the node id is neither > >>>>>>> specified by fw nor by virtual device layer and the device has > >>>>>>> no parent device. > >>>>>> > >>>>>> Is this really a problem? > >>>>> > >>>>> Not really. > >>>>> Someone need to guess the node id when it is not specified, right? > >>>> > >>>> No, why? Guessing guarantees you will get it wrong on some systems. > >>>> > >>>> Are you seeing real problems because the id is not being set? What > >>>> problem is this fixing that you can actually observe? > >>> > >>> When passing the return value of dev_to_node() to cpumask_of_node() > >>> without checking the node id if the node id is not valid, there is > >>> global-out-of-bounds detected by KASAN as below: > >> > >> OK, I seem to remember this being brought up already. And now when I > >> think about it, we really want to make cpumask_of_node NUMA_NO_NODE > >> aware. That means using the same trick the allocator does for this > >> special case. > > > > That seems reasonable to me, and much more "obvious" as to what is going > > on. > > > > Ok, thanks for the suggestion. > > For arm64 and x86, there are two versions of cpumask_of_node(). > > when CONFIG_DEBUG_PER_CPU_MAPS is defined, the cpumask_of_node() > in arch/x86/mm/numa.c is used, which does partial node id checking: > > const struct cpumask *cpumask_of_node(int node) > { > if (node >= nr_node_ids) { > printk(KERN_WARNING > "cpumask_of_node(%d): node > nr_node_ids(%u)\n", > node, nr_node_ids); > dump_stack(); > return cpu_none_mask; > } > if (node_to_cpumask_map[node] == NULL) { > printk(KERN_WARNING > "cpumask_of_node(%d): no node_to_cpumask_map!\n", > node); > dump_stack(); > return cpu_online_mask; > } > return node_to_cpumask_map[node]; > } > > when CONFIG_DEBUG_PER_CPU_MAPS is undefined, the cpumask_of_node() > in arch/x86/include/asm/topology.h is used: > > static inline const struct cpumask *cpumask_of_node(int node) > { > return node_to_cpumask_map[node]; > } I would simply go with. There shouldn't be any need for heavy weight checks that CONFIG_DEBUG_PER_CPU_MAPS has. static inline const struct cpumask *cpumask_of_node(int node) { /* A nice comment goes here */ if (node == NUMA_NO_NODE) return node_to_cpumask_map[numa_mem_id()]; return node_to_cpumask_map[node]; } -- Michal Hocko SUSE Labs