Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764475AbXLTWGb (ORCPT ); Thu, 20 Dec 2007 17:06:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764123AbXLTWGL (ORCPT ); Thu, 20 Dec 2007 17:06:11 -0500 Received: from cantor2.suse.de ([195.135.220.15]:48287 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763586AbXLTWGJ (ORCPT ); Thu, 20 Dec 2007 17:06:09 -0500 Date: Thu, 20 Dec 2007 14:04:56 -0800 From: Greg KH To: Kay Sievers Cc: Alexey Dobriyan , Greg KH , Alexey Dobriyan , akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: kobject ->k_name memory leak Message-ID: <20071220220456.GA16307@suse.de> References: <20071203092607.GA22477@localhost.sw.ru> <20071203204716.GA9734@suse.de> <20071203210959.GA1725@martell.zuzino.mipt.ru> <20071203212551.GA11962@suse.de> <20071214214823.GA10305@kroah.com> <20071215133428.GA1732@martell.zuzino.mipt.ru> <1197731956.19869.22.camel@lov.site> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1197731956.19869.22.camel@lov.site> 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: 4360 Lines: 109 On Sat, Dec 15, 2007 at 04:19:16PM +0100, Kay Sievers wrote: > On Sat, 2007-12-15 at 16:34 +0300, Alexey Dobriyan wrote: > > On Fri, Dec 14, 2007 at 01:48:23PM -0800, Greg KH wrote: > > > 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? > > > > For the record, this leak screws any testing one can do wrt module > > unload races. You can't really leave box overnight running > > modprobe/rmmod in a loop, because OOM killer will finally kick in. > > Hey, this is exactly how it was noticed at all. > > > > > Or is the above trace something that users will see when unloading > > > modules? > > > > No, it's added debugging. > > Can't we add an empty release function? It would free the name with the > current logic, right? Doh, that should be easy. Alexey, can you see if the patch below fixes this issue for you? thanks, greg k-h ------------------- --- kernel/params.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/kernel/params.c +++ b/kernel/params.c @@ -697,8 +697,18 @@ static struct kset_uevent_ops module_uev decl_subsys(module, &module_ktype, &module_uevent_ops); int module_sysfs_initialized; +static void module_release(struct kobject *kobj) +{ + /* + * Stupid empty release function to allow the memory for the kobject to + * be properly cleaned up. This will not need to be present for 2.6.25 + * with the upcoming kobject core rework. + */ +} + static struct kobj_type module_ktype = { .sysfs_ops = &module_sysfs_ops, + .release = module_release, }; /* -- 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/