Re: 4.5.0+ panic when setup loop device

From: Peter Zijlstra
Date: Thu Mar 17 2016 - 07:51:33 EST

On Thu, Mar 17, 2016 at 12:39:46PM +0100, Thomas Gleixner wrote:
> But we have to clarify and document whether holes in cpu_possible_mask are not
> allowed at all or if code like the above is simply broken.

So the general rule is that cpumasks can have holes, and exempting one
just muddles the water.

Therefore I'd call the code just plain broken.