Re: [broken-out-2007-07-20-00-22] kernel bug at kernel/params:570

Andrew Morton
2007-07-20T22:59:33Z

On Fri, 20 Jul 2007 15:50:47 -0700
Greg KH <gregkh@suse.de> wrote:

> On Fri, Jul 20, 2007 at 06:32:21PM +0200, Michal Piotrowski wrote:
> > Hi Greg,
> >
> > This looks like a sysfs bug
> > http://www.stardust.webpages.pl/files/tbf/bitis-gabonica/broken-out-2007-07-20-00-22/00003.jpg
> >
> > l *kernel_param_sysfs_setup+0x75
> > 0xc13c0894 is in kernel_param_sysfs_setup (kernel/params.c:570).
> > 565 mk->mod = THIS_MODULE;
> > 566 kobj_set_kset_s(mk, module_subsys);
> > 567 kobject_set_name(&mk->kobj, name);
> > 568 kobject_init(&mk->kobj);
> > 569 ret = kobject_add(&mk->kobj);
> > 570 BUG_ON(ret < 0);
> > 571 param_sysfs_setup(mk, kparam, num_params, name_skip);
> > 572 kobject_uevent(&mk->kobj, KOBJ_ADD);
> > 573 }
> > 574
> >
> > http://www.stardust.webpages.pl/files/tbf/bitis-gabonica/broken-out-2007-07-20-00-22/mm-config
>
> What kernel version is this happening on? The -mm tree? Can you try
> Linus's tree instead?
>
> It looks like there was some needed information right before the first
> stack dump, showing exactly what kobject was trying to be added that was
> already present. Odds are this is a kernel parameter with the same name
> as a duplicate one within the same module, but the trick is going to be
> trying to figure out what module is causing this.
>
> So it's not a sysfs bug, but rather a driver issue that this is
> catching.

In that case a BUG was way too harsh treatment, and in fact directly
contributed to our inability to debug the bug!

Can we wind that back a bit? Add some useful printks and then recover
in some fashion?