Re: kswapd hung tasks in 2.6.38-rc1

From: Andrea Arcangeli
Date: Mon Jan 31 2011 - 18:13:11 EST


On Mon, Jan 31, 2011 at 02:40:16PM -0800, Dave Hansen wrote:
> Still not a very good data point, but I ran a heavy swap load for an
> hour or so without reproducing this. But, it happened again after I
> enabled transparent huge pages. I managed to get a sysrq-t dump out of
> it:
>
> http://sr71.net/~dave/ibm/2.6.38-rc2-hang-0.txt
>
> khugepaged is one of the three running tasks. Note, I set both its
> sleep timeouts to zero to stress it out a bit.

sysrq+l? sysrq+t doesn't provide interesting info for running tasks.

> I'll keep trying to reproduce without THP.

BTW, do you have prove locking enabled? With recent git I get a
deadlock inside _raw_spin_unlock_irq with prove locking enabled and it
goes away when I disable it.
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