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

[KAMEZAWA Hiroyuki]

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'.

Attached patch works well for me, 
but I don't know much about cfq. please confirm. 

Regards,
-Kame

==
cics[]->key can be NULL.
In that case, cics[]->dead_key has key value.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>

Index: linux-2.6.25-rc2/block/cfq-iosched.c
===================================================================
--- linux-2.6.25-rc2.orig/block/cfq-iosched.c
+++ linux-2.6.25-rc2/block/cfq-iosched.c
@@ -1171,7 +1171,11 @@ call_for_each_cic(struct io_context *ioc
 			break;
 
 		called += nr;
-		index = 1 + (unsigned long) cics[nr - 1]->key;
+
+		if (!cics[nr - 1]->key)
+			index = 1 + (unsigned long) cics[nr - 1]->dead_key;
+		else
+			index = 1 + (unsigned long) cics[nr - 1]->key;
 
 		for (i = 0; i < nr; i++)
 			func(ioc, cics[i]);