Re: [BUG 2.6.25-rc3] scheduler/hotplug: some processes are dealocked when cpu is set to offline

[Yi Yang <yi.y.yang@intel.com>]

I found priority of some processes is always 0 but they are highly
related to this kind of deadlock.

What does Priority 0 mean? When and in which case is it's priority
changed to 0? When can it's priority be restored to one higher value.

A simple script to get priority 0:

===================================================================
#!/bin/sh

for file in `ls /proc/*/sched`
do
        prio=`grep prio $file | awk '{print $3;}'`
        if [ "X$prio" == "X0" ] ; then
                echo "`head -n 1 $file | awk '{print $1}'`: $prio"
        fi
done
==================================================================

[root@harwich-rh ~]# ./lsprio
migration/3: 0
migration/4: 0
migration/5: 0
migration/6: 0
migration/7: 0
migration/8: 0
migration/9: 0
migration/10: 0
migration/11: 0
migration/12: 0
migration/0: 0
migration/13: 0
migration/14: 0
migration/15: 0
grep: /proc/5244/sched: No such file or directory
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
kstopmachine: 0
watchdog/1: 0
migration/2: 0

[root@harwich-rh ~]# ps aux | grep "R<"
root         8  0.0  0.0      0     0 ?        R<   19:29   0:00
[watchdog/1]
root      6987  0.0  0.0  61144   708 pts/2    R+   20:16   0:00 grep R<
[root@harwich-rh ~]#