From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx109.postini.com [74.125.245.109]) by kanga.kvack.org (Postfix) with SMTP id 9E1316B0089 for ; Mon, 22 Oct 2012 18:52:26 -0400 (EDT) Date: Mon, 22 Oct 2012 15:52:24 -0700 From: Andrew Morton Subject: Re: [PATCH v3 2/9] suppress "Device nodeX does not have a release() function" warning Message-Id: <20121022155224.e8f306f9.akpm@linux-foundation.org> In-Reply-To: <1350629202-9664-3-git-send-email-wency@cn.fujitsu.com> References: <1350629202-9664-1-git-send-email-wency@cn.fujitsu.com> <1350629202-9664-3-git-send-email-wency@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: wency@cn.fujitsu.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, benh@kernel.crashing.org, paulus@samba.org, minchan.kim@gmail.com, kosaki.motohiro@jp.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com, Greg KH On Fri, 19 Oct 2012 14:46:35 +0800 wency@cn.fujitsu.com wrote: > From: Yasuaki Ishimatsu > > When calling unregister_node(), the function shows following message at > device_release(). > > "Device 'node2' does not have a release() function, it is broken and must > be fixed." > > The reason is node's device struct does not have a release() function. > > So the patch registers node_device_release() to the device's release() > function for suppressing the warning message. Additionally, the patch adds > memset() to initialize a node struct into register_node(). Because the node > struct is part of node_devices[] array and it cannot be freed by > node_device_release(). So if system reuses the node struct, it has a garbage. > > ... > > --- a/drivers/base/node.c > +++ b/drivers/base/node.c > @@ -252,6 +252,9 @@ static inline void hugetlb_register_node(struct node *node) {} > static inline void hugetlb_unregister_node(struct node *node) {} > #endif > > +static void node_device_release(struct device *dev) > +{ > +} > > /* > * register_node - Setup a sysfs device for a node. > @@ -263,8 +266,11 @@ int register_node(struct node *node, int num, struct node *parent) > { > int error; > > + memset(node, 0, sizeof(*node)); > + > node->dev.id = num; > node->dev.bus = &node_subsys; > + node->dev.release = node_device_release; > error = device_register(&node->dev); > > if (!error){ Greg won't like that empty ->release function ;) As you say, this device item does not reside in per-device dynamically allocated memory - it is part of an externally managed array. So a proper fix here would be to convert this storage so that it *is* dynamically allocated on a per-device basis. Or perhaps we should recognize that the whole kobject get/put/release-on-last-put model is inappropriate for these objects, and stop using it entirely. >>From Kosaki's comment, it does sound that we plan to take the first option: convert to per-device dynamically allocated memory? If so, I suggest that we just leave the warning as-is for now, until we fix things proprely. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org