linux-kernel - [PATCH v4 1/2] virtio_balloon: Restore the entire balloon after the system freeze

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Date:	Fri,  4 Dec 2015 14:37:50 +0100
From:	Petr Mladek <pmladek@...e.com>
To:	Rusty Russell <rusty@...tcorp.com.au>,
	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	Jeff Epler <jepler@...ythonic.net>, Tejun Heo <tj@...nel.org>,
	Jiri Kosina <jkosina@...e.cz>,
	virtualization@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>
Subject: [PATCH v4 1/2] virtio_balloon: Restore the entire balloon after the system freeze

fill_balloon() and leak_balloon() manipulate only a limited number
of pages in one call. This is the reason why remove_common() calls
leak_balloon() in a while cycle.

remove_common() is called also when the system is being frozen.
But fill_balloon() is called only once when the system is being
restored. It means that most of the balloon stays leaked after
the system freeze and restore.

This patch adds the missing while cycle also into virtballoon_restore().
Also it makes fill_balloon() to return the number of really modified
pages. Note that leak_balloon() already did this.

Signed-off-by: Petr Mladek <pmladek@...e.com>
---
 drivers/virtio/virtio_balloon.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 7efc32945810..d73a86db2490 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -135,9 +135,10 @@ static void set_page_pfns(u32 pfns[], struct page *page)
 		pfns[i] = page_to_balloon_pfn(page) + i;
 }
 
-static void fill_balloon(struct virtio_balloon *vb, size_t num)
+static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
 {
 	struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
+	unsigned num_allocated_pages;
 
 	/* We can only do one array worth at a time. */
 	num = min(num, ARRAY_SIZE(vb->pfns));
@@ -162,10 +163,13 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num)
 			adjust_managed_page_count(page, -1);
 	}
 
+	num_allocated_pages = vb->num_pfns;
 	/* Did we get any? */
 	if (vb->num_pfns != 0)
 		tell_host(vb, vb->inflate_vq);
 	mutex_unlock(&vb->balloon_lock);
+
+	return num_allocated_pages;
 }
 
 static void release_pages_balloon(struct virtio_balloon *vb)
@@ -581,6 +585,7 @@ static int virtballoon_freeze(struct virtio_device *vdev)
 static int virtballoon_restore(struct virtio_device *vdev)
 {
 	struct virtio_balloon *vb = vdev->priv;
+	s64 diff;
 	int ret;
 
 	ret = init_vqs(vdev->priv);
@@ -589,7 +594,9 @@ static int virtballoon_restore(struct virtio_device *vdev)
 
 	virtio_device_ready(vdev);
 
-	fill_balloon(vb, towards_target(vb));
+	diff = towards_target(vb);
+	while (diff > 0)
+		diff -= fill_balloon(vb, diff);
 	update_balloon_size(vb);
 	return 0;
 }
-- 
1.8.5.6

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