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Date:   Mon, 18 Nov 2019 17:56:24 -0500
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Khazhismel Kumykov <khazhy@google.com>
Cc:     jasowang@redhat.com, wei.w.wang@intel.com,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 2/2] virtio_balloon: fix shrinker_scan return units
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On Mon, Nov 18, 2019 at 01:38:11PM -0800, Khazhismel Kumykov wrote:
> We were returning number of virtio balloon pages, which may not be the
> same as number of system pages
>=20
> Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
> Cc: Wei Wang <wei.w.wang@intel.com>
> Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
> ---
>  drivers/virtio/virtio_balloon.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>=20
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_ball=
oon.c
> index 7cf9540a40b8..7951ece3fe24 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -802,11 +802,11 @@ static unsigned long virtio_balloon_shrinker_scan(s=
truct shrinker *shrinker,
>  =09=09pages_freed =3D shrink_free_pages(vb, pages_to_free);
> =20
>  =09if (pages_freed >=3D pages_to_free)
> -=09=09return pages_freed;
> +=09=09return pages_freed / VIRTIO_BALLOON_PAGES_PER_PAGE;
>

I'm no seeing why is this one right. shrink_free_pages gives result
in PAGE_SIZE units, right?
 =20
>  =09pages_freed +=3D shrink_balloon_pages(vb, pages_to_free - pages_freed=
);
> =20
> -=09return pages_freed;
> +=09return pages_freed / VIRTIO_BALLOON_PAGES_PER_PAGE;


My head hurts. Isn't this what patch 1 tweaked?


>  }
> =20
>  static unsigned long virtio_balloon_shrinker_count(struct shrinker *shri=
nker,
> --=20
> 2.24.0.432.g9d3f5f5b63-goog