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[79.176.6.42]) by smtp.gmail.com with ESMTPSA id y24sm9167647qki.104.2019.11.18.15.08.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Nov 2019 15:09:01 -0800 (PST) Date: Mon, 18 Nov 2019 18:08:56 -0500 From: "Michael S. Tsirkin" To: Khazhismel Kumykov Cc: jasowang@redhat.com, wei.w.wang@intel.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH 1/2] virtio_balloon: fix pages_to_free calculation Message-ID: <20191118175648-mutt-send-email-mst@kernel.org> References: <20191118213811.22017-1-khazhy@google.com> MIME-Version: 1.0 In-Reply-To: <20191118213811.22017-1-khazhy@google.com> X-MC-Unique: MLcVy1_GOK2ovlcJs0Rmrw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org So I really think we should do something like the below instead. Limit playing with balloon pages so we can gradually limit it to legacy. Testing, review would be appreciated. Signed-off-by: Michael S. Tsirkin diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloo= n.c index 226fbb995fb0..7cee05cdf3fb 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -772,6 +772,13 @@ static unsigned long shrink_free_pages(struct virtio_b= alloon *vb, =09return blocks_freed << VIRTIO_BALLOON_FREE_PAGE_ORDER; } =20 +static unsigned long leak_balloon_pages(struct virtio_balloon *vb, + unsigned long pages_to_free) +{ +=09return leak_balloon(vb, pages_to_free * VIRTIO_BALLOON_PAGES_PER_PAGE) = / +=09=09VIRTIO_BALLOON_PAGES_PER_PAGE; +} + static unsigned long shrink_balloon_pages(struct virtio_balloon *vb, =09=09=09=09=09 unsigned long pages_to_free) { @@ -782,11 +789,9 @@ static unsigned long shrink_balloon_pages(struct virti= o_balloon *vb, =09 * VIRTIO_BALLOON_ARRAY_PFNS_MAX balloon pages, so we call it =09 * multiple times to deflate pages till reaching pages_to_free. =09 */ -=09while (vb->num_pages && pages_to_free) { -=09=09pages_freed +=3D leak_balloon(vb, pages_to_free) / -=09=09=09=09=09VIRTIO_BALLOON_PAGES_PER_PAGE; -=09=09pages_to_free -=3D pages_freed; -=09} +=09while (vb->num_pages && pages_freed < pages_to_free) +=09=09pages_freed +=3D leak_balloon_pages(vb, pages_to_free); + =09update_balloon_size(vb); =20 =09return pages_freed; @@ -799,7 +804,7 @@ static unsigned long virtio_balloon_shrinker_scan(struc= t shrinker *shrinker, =09struct virtio_balloon *vb =3D container_of(shrinker, =09=09=09=09=09struct virtio_balloon, shrinker); =20 -=09pages_to_free =3D sc->nr_to_scan * VIRTIO_BALLOON_PAGES_PER_PAGE; +=09pages_to_free =3D sc->nr_to_scan; =20 =09if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) =09=09pages_freed =3D shrink_free_pages(vb, pages_to_free);