linux-kernel - Re: [PATCH 2/2] bio: Free own bvec before assigning the source bio's bvec

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Date:	Fri, 18 Dec 2015 23:29:04 +0800
From:	Minfei Huang <mnfhuang@...il.com>
To:	axboe@...nel.dk
Cc:	linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
	mhuang@...hat.com
Subject: Re: [PATCH 2/2] bio: Free own bvec before assigning the source bio's
 bvec

Sorry to bother you, since I have missed the nr_iovecs in
bio_clone_fast.

Nacked this patch.

Thanks
Minfei

On 12/18/15 at 11:02P, Minfei Huang wrote:
> This is a memory leaking during splitting the bio by the caller
> bio_clone_fast.
> 
> Clone bio may allocate its own bvec, if demanding bvec is more than
> inline bvec in function bio_alloc_bioset.
> 
> bi_io_vec is assigned to the source bio's bvec directly without freeing
> it firstly in function __bio_clone_fast.
> 
> To fix it, freeing the own bvec firstly before assigning the source
> bio's bvec.
> 
> Signed-off-by: Minfei Huang <mnfhuang@...il.com>
> ---
>  block/bio.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/block/bio.c b/block/bio.c
> index 70d9814..b24fd6e 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -581,6 +581,10 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
>  	bio_set_flag(bio, BIO_CLONED);
>  	bio->bi_rw = bio_src->bi_rw;
>  	bio->bi_iter = bio_src->bi_iter;
> +
> +	if (bio_flagged(bio, BIO_OWNS_VEC))
> +		bvec_free(bio->bi_pool->bvec_pool,
> +				bio->bi_io_vec, BIO_POOL_IDX(bio));
>  	bio->bi_io_vec = bio_src->bi_io_vec;
>  }
>  EXPORT_SYMBOL(__bio_clone_fast);
> -- 
> 2.6.3
> 
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