linux-kernel - [PATCH] Fix "notes" kobject leak

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Date:	Sun, 14 Sep 2008 12:42:25 +0400
From:	Alexey Dobriyan <adobriyan@...il.com>
To:	Greg KH <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org, akpm@...l.org
Subject: [PATCH] Fix "notes" kobject leak

On Fri, Sep 12, 2008 at 08:51:05AM -0700, Greg KH wrote:
> On Sat, Sep 06, 2008 at 09:45:22AM +0400, Alexey Dobriyan wrote:
> > On Fri, Aug 29, 2008 at 10:43:43PM -0700, Greg KH wrote:
> > > On Sat, Aug 30, 2008 at 08:42:46AM +0400, Alexey Dobriyan wrote:
> > > > 	size-32: 3511 kvasprintf+0x57/0x90
> > > > 	size-64: 3059 kobject_create+0x1c/0x40
> > > > 
> > > > These two buddies increase after every "modprobe; rmmod" sequence.
> > > 
> > > Do they also do so in mainline?
> > 
> > Yep, same bug in mainline.
> 
> Not good.  Does 2.6.26 show this as well?

Uh-oh, this was actually 10-minute exercise.



[PATCH] Fix "notes" kobject leak

It happens every rmmod if KALLSYMS=y and SYSFS=y.

	# modprobe foo

kobject: 'foo' (ffffffffa00743d0): kobject_add_internal: parent: 'module', set: 'module'
kobject: 'holders' (ffff88017e7c5770): kobject_add_internal: parent: 'foo', set: '<NULL>'
kobject: 'foo' (ffffffffa00743d0): kobject_uevent_env
kobject: 'foo' (ffffffffa00743d0): fill_kobj_path: path = '/module/foo'
kobject: 'notes' (ffff88017fa9b668): kobject_add_internal: parent: 'foo', set: '<NULL>'
	  ^^^^^

	# rmmod foo

kobject: 'holders' (ffff88017e7c5770): kobject_cleanup
kobject: 'holders' (ffff88017e7c5770): auto cleanup kobject_del
kobject: 'holders' (ffff88017e7c5770): calling ktype release
kobject: (ffff88017e7c5770): dynamic_kobj_release
kobject: 'holders': free name
kobject: 'foo' (ffffffffa00743d0): kobject_cleanup
kobject: 'foo' (ffffffffa00743d0): does not have a release() function, it is broken and must be fixed.
kobject: 'foo' (ffffffffa00743d0): auto cleanup 'remove' event
kobject: 'foo' (ffffffffa00743d0): kobject_uevent_env
kobject: 'foo' (ffffffffa00743d0): fill_kobj_path: path = '/module/foo'
kobject: 'foo' (ffffffffa00743d0): auto cleanup kobject_del
kobject: 'foo': free name

	[whooops]

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

 kernel/module.c |    1 +
 1 file changed, 1 insertion(+)

--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1174,6 +1174,7 @@ static void free_notes_attrs(struct module_notes_attrs *notes_attrs,
 			sysfs_remove_bin_file(notes_attrs->dir,
 					      &notes_attrs->attrs[i]);
 		kobject_del(notes_attrs->dir);
+		kobject_put(notes_attrs->dir);
 	}
 	kfree(notes_attrs);
 }
--
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