Re: Processes stuck on D state on Dual Opteron

[Andrew Morton <akpm@osdl.org>]

Claudio Martins <ctpm@rnl.ist.utl.pt> wrote:
>
>   I repeated the test to try to get more output from alt-sysreq-T, but it 
>  oopsed again with even less output. 
>    By the way, I have also tested 2.6.11.6 and I get stuck processes in the 
>  same way. With 2.6.9 I get a hard lockup with no working alt-sysrq, after 
>  about 30 to 60mins of stress.

It could be an md deadlock, or it could be an out-of-memory deadlock.  md
trying to allocate memory on the swapout path.

>    This is with preempt enabled (as well as BKL preempt). I want to test also 
>  without preempt and also without using MD Raid1, but I'll have to reach the 
>  machine and hit the power button, so not possible until tomorrow :-(
> 
>   The original original message in this thread containing the details of the 
>  setup and a .config is at:
> 
>  http://marc.theaimsgroup.com/?l=linux-kernel&m=111266784320156&w=2
> 
>    I am happy to test any patches and also wonder if enabling any of the 
>  options in the kernel debugging section could help in trying to find where 
>  the deadlock is.

Suggest you boot with `nmi_watchdog=0' to prevent the nmi watchdog from
cutting in during long sysrq traces.

Also, capture the `sysrq-m' output so we can see if the thing is out of
memory.