linux-kernel - Re: [PATCH] scsi: address leak in the error path of discard page allocation

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Message-ID: <20100702104824.GB26318@lst.de>
Date:	Fri, 2 Jul 2010 12:48:24 +0200
From:	Christoph Hellwig <hch@....de>
To:	Mike Snitzer <snitzer@...hat.com>
Cc:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>, axboe@...nel.dk,
	hch@....de, James.Bottomley@...e.de, linux-scsi@...r.kernel.org,
	dm-devel@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] scsi: address leak in the error path of discard page allocation

On Thu, Jul 01, 2010 at 09:03:28AM -0400, Mike Snitzer wrote:
> On Thu, Jul 01 2010 at  6:49am -0400,
> FUJITA Tomonori <fujita.tomonori@....ntt.co.jp> wrote:
> 
> > This fixes discard page leak by using q->unprep_rq_fn facility.
> > 
> > q->unprep_rq_fn is called when all the data buffer (req->bio and
> > scsi_data_buffer) in the request is freed.
> > 
> > sd_unprep() uses rq->buffer to free discard page allocated in
> > sd_prepare_discard().
> > 
> > Signed-off-by: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
> 
> Thanks for sorting this out Tomo, all 3 patches work great!
> 
> BTW, there is one remaining (rare) leak in the allocation path.
> 
> The following patch serves to fix it but I'm not sure if there is a more
> elegant way to address this.
> 
> An alternative would be to check if the page is already allocated
> (before allocating the page in scsi_setup_discard_cmnd)?

Ah, should have read your mail first, sorry..

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