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

[Christoph Hellwig <hch lst de>]

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 lab 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 lab 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..