This patch makes balloon pages movable at allocation time and introduces the
infrastructure needed to perform the balloon page migration operation.
Signed-off-by: Rafael Aquini <aquini@xxxxxxxxxx>
---
drivers/virtio/virtio_balloon.c | 96 ++++++++++++++++++++++++++++++++++++++-
include/linux/virtio_balloon.h | 6 +++
2 files changed, 100 insertions(+), 2 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index d47c5c2..53386aa 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -27,6 +27,8 @@
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
/*
* Balloon device works in 4K page units. So each page is pointed to by
@@ -140,8 +142,9 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num)
spin_lock(&vb->pfn_list_lock);
for (vb->num_pfns = 0; vb->num_pfns < num;
vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
- struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY |
- __GFP_NOMEMALLOC | __GFP_NOWARN);
+ struct page *page = alloc_page(GFP_HIGHUSER_MOVABLE |
+ __GFP_NORETRY | __GFP_NOWARN |
+ __GFP_NOMEMALLOC);
if (!page) {
if (printk_ratelimit())
dev_printk(KERN_INFO, &vb->vdev->dev,
@@ -154,6 +157,7 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num)
vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
totalram_pages--;
list_add(&page->lru, &vb->pages);
+ page->mapping = balloon_mapping;
}
/* Didn't get any? Oh well. */
@@ -195,6 +199,7 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num)
for (vb->num_pfns = 0; vb->num_pfns < num;
vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
page = list_first_entry(&vb->pages, struct page, lru);
+ page->mapping = NULL;
list_del(&page->lru);
set_page_pfns(vb->pfns + vb->num_pfns, page);
vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
@@ -365,6 +370,77 @@ static int init_vqs(struct virtio_balloon *vb)
return 0;
}
+/*
+ * Populate balloon_mapping->a_ops->migratepage method to perform the balloon
+ * page migration task.
+ *
+ * After a ballooned page gets isolated by compaction procedures, this is the
+ * function that performs the page migration on behalf of move_to_new_page(),
+ * when the last calls (page)->mapping->a_ops->migratepage.
+ *
+ * Page migration for virtio balloon is done in a simple swap fashion which
+ * follows these two steps:
+ * 1) insert newpage into vb->pages list and update the host about it;
+ * 2) update the host about the removed old page from vb->pages list;
+ */
+int virtballoon_migratepage(struct address_space *mapping,
+ struct page *newpage, struct page *page, enum migrate_mode mode)
+{
+ struct virtio_balloon *vb = (void *)mapping->backing_dev_info;
+ struct scatterlist sg;
+
+ /* balloon's page migration 1st step */
+ spin_lock(&vb->pfn_list_lock);
+ vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+ list_add(&newpage->lru, &vb->pages);
+ set_page_pfns(vb->pfns, newpage);
+ sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
+ spin_unlock(&vb->pfn_list_lock);
+ tell_host(vb, vb->inflate_vq, &sg);
+
+ /* balloon's page migration 2nd step */
+ spin_lock(&vb->pfn_list_lock);
+ vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+ set_page_pfns(vb->pfns, page);
+ sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
+ spin_unlock(&vb->pfn_list_lock);
+ tell_host(vb, vb->deflate_vq, &sg);
+
+ return 0;
+}
+
+/*
+ * Populate balloon_mapping->a_ops->invalidatepage method to help compaction on
+ * isolating a page from the balloon page list.
+ */
+void virtballoon_isolatepage(struct page *page, unsigned long mode)
+{
+ struct address_space *mapping = page->mapping;
+ struct virtio_balloon *vb = (void *)mapping->backing_dev_info;
+ spin_lock(&vb->pfn_list_lock);
+ list_del(&page->lru);
+ spin_unlock(&vb->pfn_list_lock);
+}
+
+/*
+ * Populate balloon_mapping->a_ops->freepage method to help compaction on
+ * re-inserting an isolated page into the balloon page list.
+ */
+void virtballoon_putbackpage(struct page *page)
+{
+ struct address_space *mapping = page->mapping;
+ struct virtio_balloon *vb = (void *)mapping->backing_dev_info;
+ spin_lock(&vb->pfn_list_lock);
+ list_add(&page->lru, &vb->pages);
+ spin_unlock(&vb->pfn_list_lock);
+}
+
+static const struct address_space_operations virtio_balloon_aops = {
+ .migratepage = virtballoon_migratepage,
+ .invalidatepage = virtballoon_isolatepage,
+ .freepage = virtballoon_putbackpage,
+};
+
static int virtballoon_probe(struct virtio_device *vdev)
{
struct virtio_balloon *vb;
@@ -384,6 +460,19 @@ static int virtballoon_probe(struct virtio_device *vdev)
vb->vdev = vdev;
vb->need_stats_update = 0;
+ /* Init the ballooned page->mapping special balloon_mapping */
+ balloon_mapping = kmalloc(sizeof(*balloon_mapping), GFP_KERNEL);
+ if (!balloon_mapping) {
+ err = -ENOMEM;
+ goto out_free_mapping;
+ }
+
+ INIT_RADIX_TREE(&balloon_mapping->page_tree, GFP_ATOMIC | __GFP_NOWARN);
+ INIT_LIST_HEAD(&balloon_mapping->i_mmap_nonlinear);
+ spin_lock_init(&balloon_mapping->tree_lock);
+ balloon_mapping->a_ops = &virtio_balloon_aops;
+ balloon_mapping->backing_dev_info = (void *)vb;
+
err = init_vqs(vb);
if (err)
goto out_free_vb;
@@ -398,6 +487,8 @@ static int virtballoon_probe(struct virtio_device *vdev)
out_del_vqs:
vdev->config->del_vqs(vdev);
+out_free_mapping:
+ kfree(balloon_mapping);
out_free_vb:
kfree(vb);
out:
@@ -424,6 +515,7 @@ static void __devexit virtballoon_remove(struct virtio_device *vdev)
kthread_stop(vb->thread);
remove_common(vb);
kfree(vb);
+ kfree(balloon_mapping);
}
#ifdef CONFIG_PM
diff --git a/include/linux/virtio_balloon.h b/include/linux/virtio_balloon.h
index 652dc8b..db21300 100644
--- a/include/linux/virtio_balloon.h
+++ b/include/linux/virtio_balloon.h
@@ -56,4 +56,10 @@ struct virtio_balloon_stat {
u64 val;
} __attribute__((packed));
+#if defined(CONFIG_COMPACTION)
+extern struct address_space *balloon_mapping;
+#else
+struct address_space *balloon_mapping;
+#endif
+
#endif /* _LINUX_VIRTIO_BALLOON_H */
--
1.7.10.2
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