linux-kernel - Re: [PATCH] blk-mq: free hctx->ctxs in queue's release handler

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Message-ID: <55705C5E.9080401@fb.com>
Date:	Thu, 4 Jun 2015 08:10:38 -0600
From:	Jens Axboe <axboe@...com>
To:	Ming Lei <tom.leiming@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
CC:	Stefan Seyfried <stefan.seyfried@...glemail.com>,
	NeilBrown <neilb@...e.de>, Christoph Hellwig <hch@....de>,
	"v4.0" <stable@...r.kernel.org>
Subject: Re: [PATCH] blk-mq: free hctx->ctxs in queue's release handler

On 06/04/2015 07:19 AM, Ming Lei wrote:
> On Thu, Jun 4, 2015 at 9:14 PM, Ming Lei <tom.leiming@...il.com> wrote:
>> Now blk_cleanup_queue() can be called before calling
>> del_gendisk()[1], inside which hctx->ctxs is touched
>> from blk_mq_unregister_hctx(), but the variable has
>> been freed by blk_cleanup_queue() at that time.
>>
>> So this patch moves freeing of hctx->ctxs into queue's
>> release handler for fixing the oops reported by Stefan.
>>
>> Also ctx's kobject is embedded into each ctx pointed by
>> hctx->ctxs[], which shouldn't have been released so early.
>
> Hammm, the above line is wrong and should be removed, and
> hctx->ctxs[] just stores the pointer of ctx.
>
> Jens, if you need v1, please let me know.

Yeah, lets respin it please.

-- 
Jens Axboe

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