Query about: ARM11 MPCore: preemption/task migration cache coherency

[George G. Davis]

Hello,

On May 9, 2012, at 5:11 AM, bill4carson wrote:

> Hi, All
> 
> I'm using ARM11 MPCore on linux-2.6.34, unfortunately I have random
> panic/segment fault with task migration. I noticed a patch set
> [ARM11 MPCore: preemption/task migration cache coherency fixups] to fix
> such issues in here:
> 

> http://lists.infradead.org/pipermail/linux-arm-kernel/2011-October/069851.html
> 
> It seems there is no follow ups, is there official patch to fix such
> issues?

Apologies for the delayed reply.  Yes, I believe those patches are still needed
for ARM11 MPCore, even when not using PREEMPT.  I vaguely recall at least
two cases where problems occurred w/o those patches, 1) LTP stress would
randomly fail, and 2) parallel module loading would invariably oops with a
random fault, with results similar to what you've reported later in this thread.
The most reliable test case to reproduce the failure was the parallel module
loading.  LTP stress test runs took a long time to trigger the errors.

I'm dusting off the patches and trying to resurrect the test cases to see if I can
reproduce the errors on latest kernel.org.  I'll followup with results in a day or
so.  FWIW,   I've got LTP stress running on latest kernel.org now but probably
should have resurrected the parallel module loading test case instead, as
LTP stress may take awhile to reproduce the error, if at all.

--
Regards,
George

> 
> 
> thanks
> 
> -- 
> Love each day!
> 
> --bill