Re: 2.6.24-rc2-mm1

[Greg KH <greg@kroah.com>]

On Fri, Nov 16, 2007 at 08:39:12AM +0800, Dave Young wrote:
> On Nov 16, 2007 3:23 AM, Greg KH <greg@kroah.com> wrote:
> >
> > On Wed, Nov 14, 2007 at 10:19:48AM -0800, Greg KH wrote:
> > > On Wed, Nov 14, 2007 at 06:02:07PM +0100, Jiri Kosina wrote:
> > > > On Wed, 14 Nov 2007, Jiri Kosina wrote:
> > > >
> > > > > > I'd suspect the driver tree.  I think I'll need to do a quick -mm2
> > > > > > without that tree present.
> > > > > I am just verifying whether reverting kset changes fixes this, will let
> > > > > you know soon.
> > > >
> > > > OK, so I reverted
> > > > gregkh-driver-kset-convert-block_subsys-to-use-kset_create (which made me
> > > > also revert gregkh-driver-kobject-remove-subsystem_register-functions and
> > > > gregkh-driver-kset-remove-decl_subsys-macro so that we compile). Both the
> > > > error message from lockdep and more importantly the spinlock lockup have
> > > > gone, and the system with these patches reverted boots for me fine.
> > > >
> > > > Well not that fine, I still see (which is the same backtrace that caused
> > > > the lockup with plain -rc2-mm1, but doesn't make the machine hang):
> > > >
> > > > floppy0: Floppy io-port 0x03f2 in use
> > > > WARNING: at lib/kref.c:33 kref_get()
> > > >
> > > > Call Trace:
> > > >  [<ffffffff8035bd43>] kobject_add+0x9b/0x197
> > > >  [<ffffffff8035c6e1>] kref_get+0x2f/0x36
> > > >  [<ffffffff8035b82f>] kobject_get+0x12/0x17
> > > >  [<ffffffff8035bd55>] kobject_add+0xad/0x197
> > > >  [<ffffffff802c9a36>] register_disk+0x48/0x205
> > > >  [<ffffffff80355cf3>] add_disk+0x34/0x3d
> > > >  [<ffffffff8083cd99>] rd_init+0x172/0x1e1
> > > >  [<ffffffff8082063a>] kernel_init+0x175/0x2e6
> > > >  [<ffffffff8025193c>] trace_hardirqs_on+0x115/0x139
> > > >  [<ffffffff80598769>] trace_hardirqs_on_thunk+0x35/0x3a
> > > >  [<ffffffff8025193c>] trace_hardirqs_on+0x115/0x139
> > > >  [<ffffffff8020c628>] child_rip+0xa/0x12
> > > >  [<ffffffff8020bd3f>] restore_args+0x0/0x30
> > > >  [<ffffffff808204c5>] kernel_init+0x0/0x2e6
> > > >  [<ffffffff8020c61e>] child_rip+0x0/0x12
> > >
> > > someone is trying to call kref_get on a kobject that has not been
> > > initialized yet, which could be the reason the newer patches break
> > > something, as the pointers are not set up properly with a call to
> > > kobject_init() first.
> > >
> > > But, alloc_disk() should have been called on this gendisk for it to work
> > > properly at all, unless something is trashing that structure?
> > >
> > > I'm way confused...
> >
> > This patch, as found by Dave Young, should fix the issue:
> >
> > I'll roll it into my larger patchset so that Andrew will get it
> > automatically next release, but here it is for people to use now.
> >
> > thanks,
> >
> > greg k-h
> >
> > --------------
> >
> > From: Greg Kroah-Hartman <gregkh@suse.de>
> > Subject: fix bug with adding new block devices in -mm
> >
> > need to set the kset before initializing the kobject.
> >
> >
> > ---
> >  block/genhd.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > --- a/block/genhd.c
> > +++ b/block/genhd.c
> > @@ -718,9 +718,9 @@ struct gendisk *alloc_disk_node(int mino
> >                         }
> >                 }
> >                 disk->minors = minors;
> > -               kobject_init(&disk->kobj);
> >                 disk->kobj.kset = block_kset;
> >                 disk->kobj.ktype = &ktype_block;
> > +               kobject_init(&disk->kobj);
> >                 rand_initialize_disk(disk);
> >                 INIT_WORK(&disk->async_notify,
> >                         media_change_notify_thread);
> >
> > -
> Hi,
> Could you please add signed-off by me?
> 
> Signed-off-by: Dave Young <hidave.darkstar@gmail.com>

Sure, but I've modified the original patch to not include this bug in
the first place, so there's really not much to sign off on there, sorry.

I will add your name as helping out with it, if that's ok.

thanks,

greg k-h