I'm reasonably sure the problematic change is this one: http://kernel.ubuntu.com/git?p=ubuntu/ubuntu- utopic.git;a=commit;h=8ee41919feea10de065e3102de4cbf0c57fc60ea
It was fixed upstream: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/arch/x86/kernel/smpboot.c?id=728e5653e6fdb2a0892e94a600aef8c9a036c7eb . This needs to be cherry-picked into Utopic. I'm building a Utopic kernel with that patch applied now, and will test it shortly. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1386473 Title: Not using all cores after upgrade to 14.10 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1386473/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs