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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 1D0C2C3A5A2 for ; Tue, 10 Sep 2019 07:09:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE25521019 for ; Tue, 10 Sep 2019 07:09:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406563AbfIJHJi (ORCPT ); Tue, 10 Sep 2019 03:09:38 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:33434 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729707AbfIJHJh (ORCPT ); Tue, 10 Sep 2019 03:09:37 -0400 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 1DAC3C5B758C0C66B5EB; Tue, 10 Sep 2019 15:09:36 +0800 (CST) Received: from [127.0.0.1] (10.74.191.121) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.439.0; Tue, 10 Sep 2019 15:09:26 +0800 Subject: Re: [PATCH] driver core: ensure a device has valid node id in device_add() To: Michal Hocko CC: , , , , , References: <1568009063-77714-1-git-send-email-linyunsheng@huawei.com> <20190909185035.GC2063@dhcp22.suse.cz> From: Yunsheng Lin Message-ID: <07576292-e129-5949-6a2e-45fff067ca5a@huawei.com> Date: Tue, 10 Sep 2019 15:08:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <20190909185035.GC2063@dhcp22.suse.cz> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.74.191.121] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/9/10 2:50, Michal Hocko wrote: > 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. Ok > >> Even if a device's numa node is not specified, the device really >> does belong to a node. > > What does this mean? It means some one need to guess the node id if the node is not specified. > >> 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 by node 0 missing, how do we know if node 0 is missing? by node_online(0)? > 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. Yes, I should have mentioned that in the commit log. I mentioned the below in the RFC, but somehow deleted when sending V1: "There may be explicit handling out there relying on NUMA_NO_NODE, like in nvme_probe()." > >> [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 >