Re: [PATCH v3 2/9] suppress "Device nodeX does not have a release() function" warning
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2012-10-22 22:52:27
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On Fri, 19 Oct 2012 14:46:35 +0800 wency@cn.fujitsu.com wrote:
quoted hunk ↗ jump to hunk
From: Yasuaki Ishimatsu <redacted> 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>