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

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Message-Id: <20200205163402.42627-2-david@redhat.com>
Date:   Wed,  5 Feb 2020 17:34:00 +0100
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, virtualization@...ts.linux-foundation.org,
        David Hildenbrand <david@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Wei Wang <wei.w.wang@...el.com>,
        Liang Li <liang.z.li@...el.com>
Subject: [PATCH v1 1/3] virtio-balloon: Fix memory leak when unloading while hinting is in progress

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>
---
 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