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SubjectRe: [PATCH] xen-blkback: fix memory leak when persistent grants are used
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On Thu, 2014-01-23 at 11:28 -0800, Matt Wilson wrote:
> From: Matt Rushton <mrushton@amazon.com>
>
> Currently shrink_free_pagepool() is called before the pages used for
> persistent grants are released via free_persistent_gnts(). This
> results in a memory leak when a VBD that uses persistent grants is
> torn down.

This may well be the explanation for the memory leak I was observing on
ARM last night. I'll give it a go and let you know.

> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: "Roger Pau Monné" <roger.pau@citrix.com>
> Cc: Ian Campbell <Ian.Campbell@citrix.com>
> Cc: David Vrabel <david.vrabel@citrix.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: xen-devel@lists.xen.org
> Cc: Anthony Liguori <aliguori@amazon.com>
> Signed-off-by: Matt Rushton <mrushton@amazon.com>
> Signed-off-by: Matt Wilson <msw@amazon.com>
> ---
> drivers/block/xen-blkback/blkback.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
> index 6620b73..30ef7b3 100644
> --- a/drivers/block/xen-blkback/blkback.c
> +++ b/drivers/block/xen-blkback/blkback.c
> @@ -625,9 +625,6 @@ purge_gnt_list:
> print_stats(blkif);
> }
>
> - /* Since we are shutting down remove all pages from the buffer */
> - shrink_free_pagepool(blkif, 0 /* All */);
> -
> /* Free all persistent grant pages */
> if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
> free_persistent_gnts(blkif, &blkif->persistent_gnts,
> @@ -636,6 +633,9 @@ purge_gnt_list:
> BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
> blkif->persistent_gnt_c = 0;
>
> + /* Since we are shutting down remove all pages from the buffer */
> + shrink_free_pagepool(blkif, 0 /* All */);
> +
> if (log_stats)
> print_stats(blkif);
>


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