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SubjectRe: [PATCH v2 02/10] DMA, CMA: fix possible memory leak
On Thu, Jun 12, 2014 at 12:21:39PM +0900, Joonsoo Kim wrote:
> We should free memory for bitmap when we find zone mis-match,
> otherwise this memory will leak.

Then, -stable stuff?

>
> Additionally, I copy code comment from ppc kvm's cma code to notify
> why we need to check zone mis-match.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
> index bd0bb81..fb0cdce 100644
> --- a/drivers/base/dma-contiguous.c
> +++ b/drivers/base/dma-contiguous.c
> @@ -177,14 +177,24 @@ static int __init cma_activate_area(struct cma *cma)
> base_pfn = pfn;
> for (j = pageblock_nr_pages; j; --j, pfn++) {
> WARN_ON_ONCE(!pfn_valid(pfn));
> + /*
> + * alloc_contig_range requires the pfn range
> + * specified to be in the same zone. Make this
> + * simple by forcing the entire CMA resv range
> + * to be in the same zone.
> + */
> if (page_zone(pfn_to_page(pfn)) != zone)
> - return -EINVAL;
> + goto err;

At a first glance, I thought it would be better to handle such error
before activating.
So when I see the registration code(ie, dma_contiguous_revere_area),
I realized it is impossible because we didn't set up zone yet. :(

If so, when we detect to fail here, it would be better to report more
meaningful error message like what was successful zone and what is
new zone and failed pfn number?

> }
> init_cma_reserved_pageblock(pfn_to_page(base_pfn));
> } while (--i);
>
> mutex_init(&cma->lock);
> return 0;
> +
> +err:
> + kfree(cma->bitmap);
> + return -EINVAL;
> }
>
> static struct cma cma_areas[MAX_CMA_AREAS];
> --
> 1.7.9.5

--
Kind regards,
Minchan Kim


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