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Date: Thu, 17 Mar 2016 12:51:20 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Xiong Zhou <jencce.kernel@gmail.com>,
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        Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Andreas Herrmann <aherrmann@suse.com>, Jens Axboe <axboe@kernel.dk>
Subject: Re: 4.5.0+ panic when setup loop device
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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.