I'm running Ubuntu 15.04 (now upgraded to 15.10) from a clean install on a MacBook Pro 11,1 alongside OS X. I followed instructions here. I have a problem that happens intermittently where, upon attempting to suspend, the OS locks up instead. The screen will be off, the keyboard light still on, and the machine will continue to do something (as evidenced by the very warm temperature of the laptop). However, it has become completely unrecoverable by the normal means: I'm unable to move to virtual console, turn on the screen, or perform any operation. I have to perform a hard reboot when this happens.
I've not been able to recover any information as to why it's doing this. I'm not sure what error, if any, is failing and causing this behavior. What can I do to debug this issue and figure out what is causing this failure to allow the laptop to suspend?
As a note,
most of the time this does not happen, but it happens frequently enough for it to be a real hassle (at least once or twice a week, depending on how often I'm moving around with my laptop).
UPDATE 11/2/2015: At some point (even before my upgrade to 15.10) I noticed the behavior occurring much more frequently. It's to the point where I rarely chance letting my laptop suspend lest it lock itself up and force me to reboot it (after some period of time when I come back to find it locked up and toasty). Instead I just shut it down completely, which is pretty annoying. My ASUS doesn't have the same issue running the same OS and mostly the same software configuration so I'm guessing it's a hardware issue (something is not suspending properly and making it impossible to recover after a suspend as well).
Update 12/5/2015: As of today it's been at least a few weeks without the issue, even as I try to reproduce it. I believe it may have been fixed in some update of something. I'll leave the question open for a few more weeks to see if it happens again.