Comment 17 for bug 1386473

Yep, that fixed it. stress -c 8 is now using all 8 CPUs. Please cherry-pick upstream commit 728e5653e6fdb into Utopic. :-)

Just for posterity, I'm attaching some instructive dmesg output. This is obtained by booting with the sched_debug parameter, switching the printk level to DEBUG, and offlining/onlining a CPU. (I think this info can be obtained other ways, but this was easiest.)

Notice that in the broken output, there is no sched-domain that contains more than 2 of 8 CPUs.