Hey, I've had that bug! The whole computer freezes for up to a minute and then you get a dmesg stack trace:
Kernel panic - not syncing: Watchdog detected hard LOCKUP on cpu 3
CPU: 3 PID: 17176 Comm: trinity-c95 Not tainted 3.17.0+ #87
0000000000000000 00000000f3a61725 ffff880244606bf0 ffffffff9583e9fa
ffffffff95c67918 ffff880244606c78 ffffffff9583bcc0 0000000000000010
ffff880244606c88 ffff880244606c20 00000000f3a61725 0000000000000000
Call Trace:
<NMI> [<ffffffff9583e9fa>] dump_stack+0x4e/0x7a
...
It was easily reproducible by running two or more cores at 100% for a few minutes. I wanted to be a good citizen and report it, but I wasn't able to figure out where or how you're supposed to report kernel bugs. If it's the same bug as the Phoronix article mentions, then it's not a regression because I've had the problem in 3.13 too.
Also, any distribution worth its salt will accept bugs for any package it ships and (especially for something as important as the kernel) report the bugs upstream. This may be a slow process, but it does mean that bugs introduced by distributor patches are more likely to be caught.
There is a PPA for Linus's kernel, it's great for this stuff - makes upstreamable bug reports really easy. (Also for discovering "hey, my proprietary wifi now has a free driver!")
I have an Xubuntu box with older hardware (running a pentium D something or other) which frequently experiences something similar. I have no idea if it is the same issue as either of these and always chalked it up to faulty hardware
