linux-kernel - Re: [PATCH v1 1/3] virtio-balloon: Fix memory leak when unloading while hinting is in progress

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Date:   Thu, 6 Feb 2020 03:36:26 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        virtualization@...ts.linux-foundation.org,
        Jason Wang <jasowang@...hat.com>,
        Wei Wang <wei.w.wang@...el.com>,
        Liang Li <liang.z.li@...el.com>
Subject: Re: [PATCH v1 1/3] virtio-balloon: Fix memory leak when unloading
 while hinting is in progress

On Wed, Feb 05, 2020 at 05:34:00PM +0100, David Hildenbrand wrote:
> When unloading the driver while hinting is in progress, we will not
> release the free page blocks back to MM, resulting in a memory leak.
> 
> Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
> Cc: "Michael S. Tsirkin" <mst@...hat.com>
> Cc: Jason Wang <jasowang@...hat.com>
> Cc: Wei Wang <wei.w.wang@...el.com>
> Cc: Liang Li <liang.z.li@...el.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>

Applied, thanks!

> ---
>  drivers/virtio/virtio_balloon.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 8e400ece9273..abef2306c899 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -968,6 +968,10 @@ static void remove_common(struct virtio_balloon *vb)
>  		leak_balloon(vb, vb->num_pages);
>  	update_balloon_size(vb);
>  
> +	/* There might be free pages that are being reported: release them. */
> +	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
> +		return_free_pages_to_mm(vb, ULONG_MAX);
> +
>  	/* Now we reset the device so we can clean up the queues. */
>  	vb->vdev->config->reset(vb->vdev);
>  
> -- 
> 2.24.1