Re: 2.6.19-rc5-mm2 (end earlier): WARNING at lib/kobject.c:172 kobject_init() on resume from disk

Rafael J. Wysocki
2006-11-23T13:12:13Z

On Thursday, 23 November 2006 01:39, Greg KH wrote:
> On Wed, Nov 22, 2006 at 01:44:06PM -0800, Andrew Morton wrote:
> > On Wed, 22 Nov 2006 22:07:06 +0100
> > "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
> >
> > > Hi,
> > >
> > > I get similar traces on every resume from disk on SMP systems:
> > >
> > > WARNING at lib/kobject.c:172 kobject_init()
> > >
> > > Call Trace:
> > > [<ffffffff80265559>] dump_trace+0xaa/0x3fd
> > > [<ffffffff802658e8>] show_trace+0x3c/0x52
> > > [<ffffffff80265913>] dump_stack+0x15/0x17
> > > [<ffffffff8031c1ad>] kobject_init+0x3f/0x8a
> > > [<ffffffff8031c298>] kobject_register+0x1a/0x3e
> > > [<ffffffff8038e5b4>] sysdev_register+0x5f/0xec
> > > [<ffffffff8026af39>] mce_create_device+0x79/0x103
> > > [<ffffffff8026afed>] mce_cpu_callback+0x2a/0xbd
> > > [<ffffffff8026112f>] notifier_call_chain+0x29/0x3e
> > > [<ffffffff8028e809>] raw_notifier_call_chain+0x9/0xb
> > > [<ffffffff80299f18>] _cpu_up+0xc2/0xd5
> > > [<ffffffff80299f56>] cpu_up+0x2b/0x42
> > > [<ffffffff80299fbb>] enable_nonboot_cpus+0x4e/0x9b
> > > [<ffffffff802a35da>] snapshot_ioctl+0x1a0/0x5d2
> > > [<ffffffff8023d9cd>] do_ioctl+0x5e/0x77
> > > [<ffffffff8022d785>] vfs_ioctl+0x256/0x273
> > > [<ffffffff8024770b>] sys_ioctl+0x5f/0x82
> > > [<ffffffff8025811e>] system_call+0x7e/0x83
> > > DWARF2 unwinder stuck at system_call+0x7e/0x83
> > > Leftover inexact backtrace:
> > >
> > > False positive?
> > >
> >
> > Don't know. The changelog in
> > http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/gregkh-01-driver/kobject-warn.patch
> > is pretty pathetic.
>
> Heh, I would think that it's a big "obvious", oh well.
>
> There are 2 changes in this patch.
>
> First one is to ensure that the kobject is properly initialized _before_
> kobject_init() is called. Yeah, seems funny, right? Turns out this has
> caught a lot of issues where kobject_init() is called twice on the same
> object, not a good thing at all.
>
> And this looks like that is exactly what is happening here, as you
> mention:
>
> > Perhaps mce_remove_device() isn't being called.
>
> That's probably the issue.
>
> The second change in that patch tries to enforce the "everything needs a
> release() function" rule for kobjects, but it turns out, a lot of static
> kobjects trigger this inproperly (struct bus and friends), so that can't
> go to mainline, and it only shows up if you enable CONFIG_KOBJECT_DEBUG.

CONFIG_DEBUG_KOBJECT is not set here, so it looks like kobject_init() is being
called for the second time on the same object.

Greetings,
Rafael

--
You never change things by fighting the existing reality.
R. Buckminster Fuller