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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 CF3C7C433EF for ; Mon, 9 Sep 2019 09:53:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A4175218AC for ; Mon, 9 Sep 2019 09:53:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568022833; bh=mfW3P6BM6CBGA1YX46u5V3xopt1sEe7eeb7Ur0aYW/E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=UioXk1natBzTIzdC0lNQLrri04ix7L5XoqGvqKyQMoGyK4C9RepP5yJ6euIZ/SuAu EIfgsAHu1pAseLEI6eDvzJ4sScENNewcmSUEws/6RzdkOX8hQPOmQwIrmIFVH/bLbV +UpK825ViydVXW7Cj8wl0ibTA4Fa3RpW0HRaMWpI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390033AbfIIJxw (ORCPT ); Mon, 9 Sep 2019 05:53:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:35362 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728824AbfIIJxw (ORCPT ); Mon, 9 Sep 2019 05:53:52 -0400 Received: from localhost (110.8.30.213.rev.vodafone.pt [213.30.8.110]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D81BD2086D; Mon, 9 Sep 2019 09:53:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568022831; bh=mfW3P6BM6CBGA1YX46u5V3xopt1sEe7eeb7Ur0aYW/E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=FgKUzvgE5HNfDIvO9Qi3YA1Zd9md6gM0IBsMl0CISOLizY2LyeEv2AdWh63DKwtTC k5py76lfpUGigj+4JdUcjWEP2yVzOMhFFqYW1H81jBscvvyNyktIXyRcX204k4jCms W+gFgfHpIRZjwcb4FnP8ycLFlkeomRC2kkgrcJ/k= Date: Mon, 9 Sep 2019 10:53:47 +0100 From: Greg KH To: Yunsheng Lin Cc: rafael@kernel.org, linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@kernel.org, mhocko@kernel.org, linuxarm@huawei.com Subject: Re: [PATCH] driver core: ensure a device has valid node id in device_add() Message-ID: <20190909095347.GB6314@kroah.com> 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/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? > According to discussion in [1]: > Even if a device's numa node is not specified, the device really > does belong to a node. But as we do not know the node, can we cause more harm by randomly picking one (i.e. putting it all in node 0)? > 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. > > [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); > + } Again, is this going to cause more harm than good? What happens if we leave it as "unknown", isn't that better than thinking we "know" it is in node 0? thanks, greg k-h