Messages in this thread Patch in this message | | | Date | Sat, 8 Mar 2008 22:33:08 -0800 | From | Greg KH <> | Subject | Re: [PATCH] Mark kobjects as unitialized |
| |
On Sun, Mar 09, 2008 at 03:37:16AM +0530, Balaji Rao wrote: > On Thursday 06 March 2008 11:35:59 pm Greg KH wrote: > > On Thu, Mar 06, 2008 at 11:20:50PM +0530, Balaji Rao wrote: > > > On Thursday 06 March 2008 10:35:14 pm Greg KH wrote: > > > <snip> > > > > Where exactly in the code does that happen? kobjects should not be > > > > "reused" as that implies that they are static, and not dynamically > > > > allocated, right? > > > > > > > > Which kobject is this? > > > Yes, its static. Here's the code from virt/kvm_main.c:1269 > > > > > > static struct sys_device kvm_sysdev = { > > > .id = 0, > > > .cls = &kvm_sysdev_class, > > > }; > > > > > > this sys_device is being registered/unregistered when kvm-intel is > > > loaded/unloaded. > > > > Ah, ok. I'll add this patch then. > > > > > > Ugh, is this the sys_device stuff? I hate that code... > > > > > > > Yes it is! But, why do you hate it ? > > > > For reasons like this :) > > > > kobjects should not be static. the sysdevice stuff was a hack when it > > was originally created and never touched since the mid 2.5 days. It > > needs to be fixed up a lot, and is on my TODO list, slowly getting > > closer to the top... > Hi, > > This patch does not fix it all! The problem is in fact more involved. I also get these BUG reports when I reload kvm-intel. > > BUG kmalloc-8: Object already free > [ 74.696570] ----------------------------------------------------------------------------- > [ 74.696596] > [ 74.697310] INFO: Allocated in strndup_user+0x30/0x62 age=587 cpu=2 pid=1439 > [ 74.697845] INFO: Freed in kobject_set_name_vargs+0x29/0x32 age=559 cpu=3 pid=1439 > [ 74.698008] INFO: Slab 0xc16f93a0 used=10 fp=0xf7c9d2d8 flags=0x10000c3 > [ 74.698008] INFO: Object 0xf7c9d1f8 @offset=504 fp=0xf7c9d578 > > This happens because, sysdev_class_register assigns a name to the > kobject, and kfrees the old name if any. The poisoned 'name' object > persists in case of statically allocated kobjects and as its passed to > kfree again when re registered, we get the above warning. > > So, AFAICS the best way to solve this is by fixing the kobject users > (kvm, oprofile etc.) to use dynamic kobjects instead of static ones or > memset the kobject to zero before passing it to sysdev_register.
I like the memset idea, how about this patch instead?
thanks,
greg k-h
--- a/drivers/base/sys.c +++ b/drivers/base/sys.c @@ -133,6 +133,7 @@ int sysdev_class_register(struct sysdev_ pr_debug("Registering sysdev class '%s'\n", kobject_name(&cls->kset.kobj)); INIT_LIST_HEAD(&cls->drivers); + memset(&cls->kset.kobj, 0x00, sizeof(struct kobject)); cls->kset.kobj.parent = &system_kset->kobj; cls->kset.kobj.ktype = &ktype_sysdev_class; cls->kset.kobj.kset = system_kset;
| |