[BUG] Linux 2.6.25-rc2 - Regression from 2.6.24-rc1-git1 softlockup while bootup on powerpc

[KAMEZAWA Hiroyuki]

On Tue, 19 Feb 2008 09:36:34 +0100
Jens Axboe <jens.axboe at oracle.com> wrote:

> On Tue, Feb 19 2008, KAMEZAWA Hiroyuki wrote:
> > On Sun, 17 Feb 2008 20:29:13 +0100
> > Jens Axboe <jens.axboe at oracle.com> wrote:
> > 
> > > It's odd stuff. Could you perhaps try and add some printks to
> > > block/cfq-iosched.c:call_for_each_cic(), like dumping the 'nr' return
> > > from radix_tree_gang_lookup() and the pointer value of cics[i] in the
> > > for() loop after the lookup?
> > > 
> > I met the same issue on ia64/NUMA box.
> > seems cisc[]->key is NULL and index for radix_tree_gang_lookup() was
> > always '1'.
> 
> Why does it keep repeating then? If ->key is NULL, the next lookup index
> should be 1UL.
> 
when I inserted printk here
==
	for (i = 0; i < nr; i++)
		func(ioc, cics[i]);
	printk("%d %lx\n", nr, index);
==
index was always "1" and  nr was always 32.

So, cics[31]->key was always NULL when index=1 is passed to radix_tree_gang_lookup().


> But I think the radix 'scan over entire tree' is a bit fragile. This
> patch adds a parallel hlist for ease of properly browsing the members,
> does that work for you? It compiles, but I haven't booted it here yet...
> 
will try. please wait a bit.

Thanks,
-Kame