Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758164AbXLNVwc (ORCPT ); Fri, 14 Dec 2007 16:52:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753262AbXLNVwW (ORCPT ); Fri, 14 Dec 2007 16:52:22 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:39534 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753181AbXLNVwV (ORCPT ); Fri, 14 Dec 2007 16:52:21 -0500 Date: Fri, 14 Dec 2007 13:48:23 -0800 From: Greg KH To: Greg KH Cc: Alexey Dobriyan , Alexey Dobriyan , akpm@osdl.org, linux-kernel@vger.kernel.org, kay.sievers@vrfy.org Subject: Re: kobject ->k_name memory leak Message-ID: <20071214214823.GA10305@kroah.com> References: <20071203092607.GA22477@localhost.sw.ru> <20071203204716.GA9734@suse.de> <20071203210959.GA1725@martell.zuzino.mipt.ru> <20071203212551.GA11962@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071203212551.GA11962@suse.de> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2691 Lines: 64 On Mon, Dec 03, 2007 at 01:25:51PM -0800, Greg KH wrote: > On Tue, Dec 04, 2007 at 12:09:59AM +0300, Alexey Dobriyan wrote: > > On Mon, Dec 03, 2007 at 12:47:16PM -0800, Greg KH wrote: > > > On Mon, Dec 03, 2007 at 12:26:07PM +0300, Alexey Dobriyan wrote: > > > > Hi, Greg! > > > > > > > > Commit ce2c9cb0259acd2aed184499ebe41ab00da13b25 aka > > > > "kobject: remove the static array for the name" introduced memory leak > > > > of a module name after modprobe/rmmod. Apparently for modules ->release > > > > callback is NULL. > > > > > > > > kobject_cleanup: ->release = 00000000, name = 'foo_sysctl' > > > > Pid: 1927, comm: rmmod Not tainted 2.6.24-rc3-e1cca7e8d484390169777b423a7fe46c7021fec1 #5 > > > > [] kobject_cleanup+0xb8/0xc0 > > > > [] kobject_release+0x0/0x10 > > > > [] kref_put+0x2b/0xa0 > > > > [] _spin_unlock+0x25/0x40 > > > > [] free_module+0x78/0xd0 > > > > [] sys_delete_module+0x12f/0x1a0 > > > > > > Hm, _which_ kobject associated with a module, there are 3 of them I > > > think :) > > > > Ouch! > > > > > They should all have a release function, and if they do not, we think > > > it's a "static" kobject and it is not safe to free that name. > > > > > > I've been working on cleaning this up a lot in the -mm tree with over 80 > > > patches for the kset/kobject apis and interfaces. > > > > > > But if we have a dynamic kobject, and we aren't freeing it properly, > > > please let me know which one it is and I'll work to fix it for 2.6.24. > > > > The one which is passed to kobject_set_name() in mod_sysfs_init().. > > That one should be set to the module_ktype, which is in kernel/params.c, > so the release function there should... oh crap, there is no release > function. That's a bug. After I get out of meetings tonight I'll write > up a patch for that, unless someone beats me to it :) Ok, this is a mess. We can't really have a release function for this kobject, as the structure it is embedded it has it's own memory management issues. To fix this properly is going to take some major kobject/module surgery, it's not a simple fix at all. I'll tackle it for 2.6.25, as it fits in nicely with the other kobject rework that I've already done in the -mm tree. So, for now, can we just live with this tiny memory leak on module unload? Or is the above trace something that users will see when unloading modules? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/