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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 A5237C4740A for ; Mon, 9 Sep 2019 18:50:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77CFD21A4A for ; Mon, 9 Sep 2019 18:50:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568055040; bh=8fdL+eBnW+jbpK82CyJ+IUy8PMnmuScQZjvnA9UNQnY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=KbqHHrGdGDYUvv5K6rioRr1tQ+rBfqwigFnuABWjaP49yzOz5hwXhhAmREoRzAezI WVWVNXjK7jdz4r4VkDUz0ItfNx0adeW/NppGVgUwQ1HDMHS+/ulzALxkzZZAgYzkAv U3+QO5Sd0R+wUqc1/+I3kPWjaxH5iGk5Re8O5jNc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732481AbfIISuj (ORCPT ); Mon, 9 Sep 2019 14:50:39 -0400 Received: from mx2.suse.de ([195.135.220.15]:60300 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726814AbfIISuj (ORCPT ); Mon, 9 Sep 2019 14:50:39 -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 60815AE1C; Mon, 9 Sep 2019 18:50:37 +0000 (UTC) Date: Mon, 9 Sep 2019 20:50:35 +0200 From: Michal Hocko To: Yunsheng Lin Cc: gregkh@linuxfoundation.org, 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: <20190909185035.GC2063@dhcp22.suse.cz> References: <1568009063-77714-1-git-send-email-linyunsheng@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1568009063-77714-1-git-send-email-linyunsheng@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 Mon 09-09-19 14:04:23, 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. > > According to discussion in [1]: Please do not reference important parts of the justification via a link. Just quote the relevant part to the changelog. It is just too easy that external links die - not to mention lkml.org. > Even if a device's numa node is not specified, the device really > does belong to a node. What does this mean? > This patch sets the device node to node 0 in device_add() if the > device's node id is not specified and it either has no parent > device, or the parent device also does not have a valid node id. Why is node 0 special? I have seen platforms with node 0 missing or being memory less. The changelog also lacks an actual problem descripton. Why do we even care about NUMA_NO_NODE? E.g. the page allocator interprets NUMA_NO_NODE as the closest node with a memory. And by closest it really means to the CPU which is performing the allocation. > [1] https://lkml.org/lkml/2019/9/2/466 > > Signed-off-by: Yunsheng Lin > --- > Changelog RFC -> v1: > 1. Drop log error message and use a "if" instead of "? :". > 2. Drop the RFC tag. > --- > drivers/base/core.c | 10 +++++++--- > include/linux/numa.h | 2 ++ > 2 files changed, 9 insertions(+), 3 deletions(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 1669d41..f79ad20 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -2107,9 +2107,13 @@ int device_add(struct device *dev) > if (kobj) > dev->kobj.parent = kobj; > > - /* use parent numa_node */ > - if (parent && (dev_to_node(dev) == NUMA_NO_NODE)) > - set_dev_node(dev, dev_to_node(parent)); > + /* use parent numa_node or default node 0 */ > + if (!numa_node_valid(dev_to_node(dev))) { > + if (parent && numa_node_valid(dev_to_node(parent))) > + set_dev_node(dev, dev_to_node(parent)); > + else > + set_dev_node(dev, 0); > + } > > /* first, register with generic layer. */ > /* we require the name to be set before, and pass NULL */ > diff --git a/include/linux/numa.h b/include/linux/numa.h > index 110b0e5..eccc757 100644 > --- a/include/linux/numa.h > +++ b/include/linux/numa.h > @@ -13,4 +13,6 @@ > > #define NUMA_NO_NODE (-1) > > +#define numa_node_valid(node) ((unsigned int)(node) < nr_node_ids) > + > #endif /* _LINUX_NUMA_H */ > -- > 2.8.1 -- Michal Hocko SUSE Labs