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From: Rusty Russell <rusty@rustcorp.com.au>
To: "Denis V. Lunev" <den@openvz.org>
Subject: Re: [PATCH 3/4] modules: proper cleanup of kobject without CONFIG_SYSFS
Date: Thu, 22 May 2008 19:20:22 +1000
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       linux-kernel@vger.kernel.org, Kay Sievers <kay.sievers@vrfy.org>,
       Greg Kroah-Hartman <gregkh@suse.de>
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On Tuesday 20 May 2008 19:59:48 Denis V. Lunev wrote:
> kobject: '<NULL>' (ffffffffa0104050): is not initialized, yet kobject_put()

Thanks Denis.

This patch masks a deeper problem; looks like you can't load any modules with 
CONFIG_SYSFS=n:

kernel/module.c:
int mod_sysfs_init(struct module *mod)
{
	int err;
	struct kobject *kobj;

	if (!module_sysfs_initialized) {
		printk(KERN_ERR "%s: module sysfs not initialized\n",
		       mod->name);
		err = -EINVAL;
		goto out;
	}

AFAICT, module_sysfs_initialized is not ever set if !CONFIG_SYSFS.

I can't see the point of module_sysfs_initialized.  It was introduced by Greg 
in commit 823bccfc ("remove "struct subsystem" as it is no longer needed").

Greg, what were you trying to do here?  Modules can't be loaded before 
param_sysfs_init(): are you trying to handle the case where the 
kset_create_and_add() fails?

Thanks,
Rusty.