On Sat, Sep 30, 2017 at 12:05:52PM +0800, Wei Wang wrote:
> +static inline void xb_set_page(struct virtio_balloon *vb,
> + struct page *page,
> + unsigned long *pfn_min,
> + unsigned long *pfn_max)
> +{
> + unsigned long pfn = page_to_pfn(page);
> +
> + *pfn_min = min(pfn, *pfn_min);
> + *pfn_max = max(pfn, *pfn_max);
> + xb_preload(GFP_KERNEL);
> + xb_set_bit(&vb->page_xb, pfn);
> + xb_preload_end();
> +}
> +
So, this will allocate memory
...
> @@ -198,9 +327,12 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
> struct page *page;
> struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
> LIST_HEAD(pages);
> + bool use_sg = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG);
> + unsigned long pfn_max = 0, pfn_min = ULONG_MAX;
>
> - /* We can only do one array worth at a time. */
> - num = min(num, ARRAY_SIZE(vb->pfns));
> + /* Traditionally, we can only do one array worth at a time. */
> + if (!use_sg)
> + num = min(num, ARRAY_SIZE(vb->pfns));
>
> mutex_lock(&vb->balloon_lock);
> /* We can't release more pages than taken */
And is sometimes called on OOM.
I suspect we need to
1. keep around some memory for leak on oom
2. for non oom allocate outside locks
--
MST
