Hi Thomas,

On Tuesday 15 September 2015 00:05:31 Thomas Gleixner wrote:

Please CC lkml on bug reports for RT.

Okay.

quoted

When running the system at least every other boot this kernel spits out
massive "scheduling while atomic" reports.

I doubt that this only happens on every other boot. This is a
systematic failure.

That was one of the confusing things: we booted the machine and got a bunch 
off "scheduling while atomic" reports and we re-booted it and it was silent. 
That's why we thought it might be a race instead of a systematic failure.

[...]
If you encounter such a 'confusing' problem the next time, then look
out for commonalities, AKA patterns. 99% of all problems can be
decoded via patterns. And if you look at the other call chains you'll
find more instances of those pte_*_lock() calls, which all end up in
kmap_atomic().

Sounds easy. But we stared with two developers on the code and the bug traces 
and were lost in the code. Seems you are in a pole position due to your 
experience with the RT preempt code.

The good news: I tried your suggested change on my system and reboot it again 
and again since an hour now and no more "scheduling while atomic" reports 
occur. \o/

Thank you very much
Juergen

-- 
Pengutronix e.K.                              | Juergen Borleis             |
Industrial Linux Solutions                    | http://www.pengutronix.de/  |
--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html