This is a note to let you know that I've just added the patch titled
virtio_balloon: fix race by fill and leak
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio_balloon-fix-race-by-fill-and-leak.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f68b992bbb474641881932c61c92dcfa6f5b3689 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@xxxxxxxxxx>
Date: Mon, 28 Dec 2015 08:35:12 +0900
Subject: virtio_balloon: fix race by fill and leak
From: Minchan Kim <minchan@xxxxxxxxxx>
commit f68b992bbb474641881932c61c92dcfa6f5b3689 upstream.
During my compaction-related stuff, I encountered a bug
with ballooning.
With repeated inflating and deflating cycle, guest memory(
ie, cat /proc/meminfo | grep MemTotal) is decreased and
couldn't be recovered.
The reason is balloon_lock doesn't cover release_pages_balloon
so struct virtio_balloon fields could be overwritten by race
of fill_balloon(e,g, vb->*pfns could be critical).
This patch fixes it in my test.
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_balloon.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -209,8 +209,8 @@ static unsigned leak_balloon(struct virt
*/
if (vb->num_pfns != 0)
tell_host(vb, vb->deflate_vq);
- mutex_unlock(&vb->balloon_lock);
release_pages_balloon(vb);
+ mutex_unlock(&vb->balloon_lock);
return num_freed_pages;
}
Patches currently in stable-queue which might be from minchan@xxxxxxxxxx are
queue-4.4/virtio_balloon-fix-race-by-fill-and-leak.patch
queue-4.4/virtio_balloon-fix-race-between-migration-and-ballooning.patch
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