Re: raid related kernel hang in 2.6.36

[Neil Brown <neilb@suse.de>]

On Wed, 24 Nov 2010 22:34:21 +0800 Du Jun <dujun@perabytes.com> wrote:

> Their's no dmesg information at all before the hang. The system just 
> hangs suddenly without any kernel printk or oops.
> 
> mdadm version is debian lenny version 2.6.7.2-3
> 
> I will get mdadm -E & mdadm -D informations tomorrow but I doubt they 
> are useful.

Probably not, but they wouldn't hurt either.

What would really help is if you could capture the result of
    sysrq-T

which I accept might be a challenge depending on how hard the machine really
has frozen.

Also, make sure the LOCKUP_DETECTOR config options are set, and wait a few
minutes after the hand to see if something pops up.

I'll try to see if I can reproduce, but I don't have 16 disks so it may not
work.

NeilBrown


> 
> Johnson
> on 2010/11/24 22:19, Mathias Burén  wrote:
> > Hi,
> >
> > I suppose a few logs would be interesting. (dmesg, mdadm -E (hdds),
> > mdadm -D md10, zcat /proc/config.gz, mdadm version)
> >
> > Regards,
> > // Mathias
> >
> > 2010/11/24 Du Jun<dujun@perabytes.com>:
> >    
> >> Hi,
> >> We just quick tested the raid stability under the vanilla 2.6.36 kernel
> >> and got an unstable result.
> >>
> >> first, we create a raid5 array using 16 sata disks:
> >>
> >> mdadm -C /dev/md10 -l 5 -n 16 /dev/sd[b-q]
> >>
> >> then use dd to stress the io:
> >>
> >> dd if=/dev/zero of=/dev/md10 bs=1M
> >>
> >> After a while, usually several minutes, the system hangs. It looks like
> >> some kind of kernel deadlock. ping to this machine could get timely
> >> response, however, any other process just hangs.
> >>
> >> It is easily reproducible and everytime the test result is a system hang.
> >>
> >> Johnson
> >>
> >> --
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> >    
> 
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