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Date: Tue, 19 Feb 2008 10:01:19 +0100
From: Jens Axboe <jens.axboe@oracle.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [BUG] Linux 2.6.25-rc2 - Regression from 2.6.24-rc1-git1
	softlockup while bootup on powerpc
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Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>,
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On Tue, Feb 19 2008, KAMEZAWA Hiroyuki wrote:
> On Tue, 19 Feb 2008 09:36:34 +0100
> Jens Axboe <jens.axboe@oracle.com> wrote:
> 
> > On Tue, Feb 19 2008, KAMEZAWA Hiroyuki wrote:
> > > On Sun, 17 Feb 2008 20:29:13 +0100
> > > Jens Axboe <jens.axboe@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.
> > 
> > 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...
> > 
> Works well for me and my box booted !

Super, I'll get it upstream. Thanks for testing and debugging!

-- 
Jens Axboe