> On Thu, Nov 15, 2007 at 04:14:07PM +0800, Dave Young wrote:
> > On Thu, Nov 15, 2007 at 03:38:13AM +0100, Kay Sievers wrote:
> > > On Thu, 2007-11-15 at 09:01 +0800, Dave Young wrote:
> > > > On Nov 15, 2007 5:27 AM, Kay Sievers <kay.sievers@vrfy.org> wrote:
> > > > > On Wed, 2007-11-14 at 20:19 +0100, Jiri Kosina wrote:
> > > > > > On Wed, 14 Nov 2007, Kay Sievers wrote:
> > > > > >
> > > > > > > Could it be an init-order problem, where something tries to use the
> > > > > > > block subsystem? Before it is initialized with:
> > > > > > > block/genhd.c :: subsys_initcall(genhd_device_init);
> > > > > > > If that's the case, we have an old bug that nobody noticed with static
> > > > > > > structures, which are zeroed that time, but definitely not properly
> > > > > > > initialized. I'll try to build loop non-modular now, and see if that
> > > > > > > makes the bug appear here.
> > > > >
> > > > > > my .config with which I reproduc this on 2.6.24-rc2-mm1 reliably can be
> > > > > > obtained from
http://www.jikos.cz/jikos/junk/.config
> > > > >
> > > > > Hmm, that config doesn't do anything here, and if I make it boot, it
> > > > > does not show the bug.
> > > > >
> > > > > Could you possibly enable kobject debugging and see if that exposes
> > > > > something, maybe something goes wrong with the kset refcount and it gets
> > > > > released while in use.
> > > > >
> > > > Hi,
> > > > I would do that.
> > >
> > > That would be great.
> > >
> > > > BTW, The bug report as EIP at __list_add with CONFIG_DEBUG_LIST=y
> > >
> > > Yeah, that hints that the kset, which contains the list, is not
> > > allocated at the time it is used, or it is already released (kfree)
> > > again by some buggy logic.
> > Yes, I debugged it, there's some new findings.
> > It is freed by put_disk.
> > The floppy driver alloc_disk and then call put_disk without register_disk.
> > in kobject_cleanup line 551:
> > if(s)
> > kset_put(s);
> > Now the kset is set in alloc_disk after kobject_init, so it is not refereced yet.
> > please try this patch:
> >
> > block/genhd.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff -upr linux/block/genhd.c linux.new/block/genhd.c
> > --- linux/block/genhd.c 2007-11-15 15:59:11.000000000 +0800
> > +++ linux.new/block/genhd.c 2007-11-15 15:59:39.000000000 +0800
> > @@ -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);
>
> Ah, yes, that is a bug, and it's my fault, let me go fix that in my
> patch series.
