Tomasz Chmielewski wrote:
I'm trying to use ballooning with kvm-83.
Although I'm able to limit the guest's memory, when I try to increase
it right after that, I get "vballoon: page allocation failure.
order:0" followed by a kernel panic.
Is it expected?
The guest is running Debian Lenny with 2.6.26 kernel. It had initially
256 MB memory.
It's a guest bug, fixed in 2.6.27 by
commit 532a6086e35fa3b5761e68af36d4e42a550eba15
Author: Anthony Liguori <aliguori@xxxxxxxxxx>
Date: Mon Aug 18 17:15:31 2008 -0500
virtio_balloon: fix towards_target when deflating balloon
Both v and vb->num_pages are u32 and unsigned int respectively. If
v is less
than vb->num_pages (and it is, when deflating the balloon), the
result is a
very large 32-bit number. Since we're returning a s64, instead of
getting the
same negative number we desire, we get a very large positive number.
This handles the case where v < vb->num_pages and ensures we get a
small,
negative, s64 as the result.
Rusty: please push this for 2.6.27-rc4. It's probably appropriate
for the
stable tree too as it will cause an unexpected OOM when ballooning.
Signed-off-by: Anthony Liguori <aliguori@xxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx> (simplified)
diff --git a/drivers/virtio/virtio_balloon.c
b/drivers/virtio/virtio_balloon.c
index bfef604..62eab43 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -158,7 +158,7 @@ static inline s64 towards_target(struct
virtio_balloon *vb)
vb->vdev->config->get(vb->vdev,
offsetof(struct virtio_balloon_config,
num_pages),
&v, sizeof(v));
- return v - vb->num_pages;
+ return (s64)v - vb->num_pages;
}
static void update_balloon_size(struct virtio_balloon *vb)
--
error compiling committee.c: too many arguments to function
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