On 7/13/17 1:16 PM, Jerome Glisse wrote:

> I updated hmm-next with a patch that might fix some other issues but i am
> still trying to get this dead lock you are seing. Does it happens quickly
> with the test program ?
>
> I can't see how it dead lock on the page lock bit. Going over and over all
> code path we always unlock page once we are done or when we back off from
> migration. So far i haven't been able to reproduce thought i haven't had
> much time to test as other thing kept me busy. I should be back looking into
> that tomorrow.
>
> https://cgit.freedesktop.org/~glisse/linux/log/?h=hmm-next
>
> Cheers,
> JA(C)rA'me

Hi Jerome,

The issue persists in the updated hmm-next. The test program hangs on 
the first run on my 12-core SMT system:

$ sudo ./run.sh
&&& 2 migrate threads, 2 read threads: STARTING
&&& 2 migrate threads, 2 read threads: PASSED
&&& 2 migrate threads, 3 read threads: STARTING
&&& 2 migrate threads, 3 read threads: PASSED
&&& 2 migrate threads, 4 read threads: STARTING
&&& 2 migrate threads, 4 read threads: PASSED
&&& 3 migrate threads, 2 read threads: STARTING
....
[no progress being made]

Please find attached a new kernel log with blocked tasks shown and my 
kernel config. I hope that is helpful.

Thanks,

-- 
Evgeny Baskakov
NVIDIA