linux-kernel - Re: [PATCH] blk-mq: Use proper cpumask iterator

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Message-ID: <56EEC2D6.5090603@kernel.dk>
Date:	Sun, 20 Mar 2016 09:33:42 -0600
From:	Jens Axboe <axboe@...nel.dk>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Xiong Zhou <jencce.kernel@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
	Andreas Herrmann <aherrmann@...e.com>
Subject: Re: [PATCH] blk-mq: Use proper cpumask iterator

On 03/19/2016 04:30 AM, Thomas Gleixner wrote:
> queue_for_each_ctx() iterates over per_cpu variables under the assumption that
> the possible cpu mask cannot have holes. That's wrong as all cpumasks can have
> holes. In case there are holes the iteration ends up accessing uninitialized
> memory and crashing as a result.
>
> Replace the macro by a proper for_each_possible_cpu() loop and drop the unused
> macro blk_ctx_sum() which references queue_for_each_ctx().

Thanks Thomas, applied.

-- 
Jens Axboe