linux-kernel - Re: [3/4] DST: Network state machine.

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Message-ID: <20071214063558.GA12017@2ka.mipt.ru>
Date:	Fri, 14 Dec 2007 09:35:58 +0300
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	lkml <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Cc:	"dmonakhov@...ru" <DmitryMonakhov@....mipt.ru>
Subject: Re: [3/4] DST: Network state machine.

On Thu, Dec 13, 2007 at 11:43:43PM +0300, Dmitry Monakhov (dmonakhov@...ru) wrote:
> On 14:47 Mon 10 Dec     , Evgeniy Polyakov wrote:
> > 
> > Network state machine.
> > 
> > Includes network async processing state machine and related tasks.
> Hi, I've tried to play a little bit with DST and discover huge memory
> leak. Every read request from remote node result in bio + bio's pages leak.
> 
> Data flow:
> ->kst_export_ready 		## prepare and submit bio 
>   ->generic_make_request(bio) 	## submit it
> 
> ->kst_export_read_end_io	## block layer call bio_end_io callback
> 
> ->kst_thread_process_state	## process ready requests
>   ->kst_data_callback
>      ->kst_data_process_bio	## submit pages to network layer
>   ->kst_complete_req
>      ->kst_bio_endio
>        ->kst_export_read_end_io ## WoW we calling the same bio_end_io 
> 				## callback twice 
>      ->dst_free_request(req);   ## request will be destroyed but it's bio
> 				## and all bio's pages wasn't released.
> We may release bio's pages after it was sent to network, it is safe because
> sendpage() already called get_page(). I've attached simple patch which 
> this this.

Yes, your patch looks good.
Thanks a lot, Dmitry.

-- 
	Evgeniy Polyakov
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