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-rw-r--r--drivers/virtio/virtio_balloon.c103
1 files changed, 47 insertions, 56 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 9e0177529bad..0ef16566c3f3 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/balloon_compaction.h>
+#include <linux/oom.h>
#include <linux/wait.h>
#include <linux/mm.h>
#include <linux/mount.h>
@@ -28,7 +29,9 @@
*/
#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
-#define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
+/* Maximum number of (4k) pages to deflate on OOM notifications. */
+#define VIRTIO_BALLOON_OOM_NR_PAGES 256
+#define VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY 80
#define VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG (__GFP_NORETRY | __GFP_NOWARN | \
__GFP_NOMEMALLOC)
@@ -114,9 +117,12 @@ struct virtio_balloon {
/* Memory statistics */
struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
- /* To register a shrinker to shrink memory upon memory pressure */
+ /* Shrinker to return free pages - VIRTIO_BALLOON_F_FREE_PAGE_HINT */
struct shrinker shrinker;
+ /* OOM notifier to deflate on OOM - VIRTIO_BALLOON_F_DEFLATE_ON_OOM */
+ struct notifier_block oom_nb;
+
/* Free page reporting device */
struct virtqueue *reporting_vq;
struct page_reporting_dev_info pr_dev_info;
@@ -830,50 +836,13 @@ static unsigned long shrink_free_pages(struct virtio_balloon *vb,
return blocks_freed * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
}
-static unsigned long leak_balloon_pages(struct virtio_balloon *vb,
- unsigned long pages_to_free)
-{
- return leak_balloon(vb, pages_to_free * VIRTIO_BALLOON_PAGES_PER_PAGE) /
- VIRTIO_BALLOON_PAGES_PER_PAGE;
-}
-
-static unsigned long shrink_balloon_pages(struct virtio_balloon *vb,
- unsigned long pages_to_free)
-{
- unsigned long pages_freed = 0;
-
- /*
- * One invocation of leak_balloon can deflate at most
- * VIRTIO_BALLOON_ARRAY_PFNS_MAX balloon pages, so we call it
- * multiple times to deflate pages till reaching pages_to_free.
- */
- while (vb->num_pages && pages_freed < pages_to_free)
- pages_freed += leak_balloon_pages(vb,
- pages_to_free - pages_freed);
-
- update_balloon_size(vb);
-
- return pages_freed;
-}
-
static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker,
struct shrink_control *sc)
{
- unsigned long pages_to_free, pages_freed = 0;
struct virtio_balloon *vb = container_of(shrinker,
struct virtio_balloon, shrinker);
- pages_to_free = sc->nr_to_scan;
-
- if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
- pages_freed = shrink_free_pages(vb, pages_to_free);
-
- if (pages_freed >= pages_to_free)
- return pages_freed;
-
- pages_freed += shrink_balloon_pages(vb, pages_to_free - pages_freed);
-
- return pages_freed;
+ return shrink_free_pages(vb, sc->nr_to_scan);
}
static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker,
@@ -881,12 +850,22 @@ static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker,
{
struct virtio_balloon *vb = container_of(shrinker,
struct virtio_balloon, shrinker);
- unsigned long count;
- count = vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE;
- count += vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
+ return vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
+}
+
+static int virtio_balloon_oom_notify(struct notifier_block *nb,
+ unsigned long dummy, void *parm)
+{
+ struct virtio_balloon *vb = container_of(nb,
+ struct virtio_balloon, oom_nb);
+ unsigned long *freed = parm;
+
+ *freed += leak_balloon(vb, VIRTIO_BALLOON_OOM_NR_PAGES) /
+ VIRTIO_BALLOON_PAGES_PER_PAGE;
+ update_balloon_size(vb);
- return count;
+ return NOTIFY_OK;
}
static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb)
@@ -971,7 +950,23 @@ static int virtballoon_probe(struct virtio_device *vdev)
VIRTIO_BALLOON_CMD_ID_STOP);
spin_lock_init(&vb->free_page_list_lock);
INIT_LIST_HEAD(&vb->free_page_list);
+ /*
+ * We're allowed to reuse any free pages, even if they are
+ * still to be processed by the host.
+ */
+ err = virtio_balloon_register_shrinker(vb);
+ if (err)
+ goto out_del_balloon_wq;
+ }
+
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
+ vb->oom_nb.notifier_call = virtio_balloon_oom_notify;
+ vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY;
+ err = register_oom_notifier(&vb->oom_nb);
+ if (err < 0)
+ goto out_unregister_shrinker;
}
+
if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
/* Start with poison val of 0 representing general init */
__u32 poison_val = 0;
@@ -986,15 +981,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
virtio_cwrite(vb->vdev, struct virtio_balloon_config,
poison_val, &poison_val);
}
- /*
- * We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a
- * shrinker needs to be registered to relieve memory pressure.
- */
- if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
- err = virtio_balloon_register_shrinker(vb);
- if (err)
- goto out_del_balloon_wq;
- }
vb->pr_dev_info.report = virtballoon_free_page_report;
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
@@ -1003,12 +989,12 @@ static int virtballoon_probe(struct virtio_device *vdev)
capacity = virtqueue_get_vring_size(vb->reporting_vq);
if (capacity < PAGE_REPORTING_CAPACITY) {
err = -ENOSPC;
- goto out_unregister_shrinker;
+ goto out_unregister_oom;
}
err = page_reporting_register(&vb->pr_dev_info);
if (err)
- goto out_unregister_shrinker;
+ goto out_unregister_oom;
}
virtio_device_ready(vdev);
@@ -1017,8 +1003,11 @@ static int virtballoon_probe(struct virtio_device *vdev)
virtballoon_changed(vdev);
return 0;
-out_unregister_shrinker:
+out_unregister_oom:
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
+ unregister_oom_notifier(&vb->oom_nb);
+out_unregister_shrinker:
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
virtio_balloon_unregister_shrinker(vb);
out_del_balloon_wq:
if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
@@ -1061,6 +1050,8 @@ static void virtballoon_remove(struct virtio_device *vdev)
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
page_reporting_unregister(&vb->pr_dev_info);
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
+ unregister_oom_notifier(&vb->oom_nb);
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
virtio_balloon_unregister_shrinker(vb);
spin_lock_irq(&vb->stop_update_lock);
vb->stop_update = true;
generated by cgit v1.2.3 (git 2.39.1) at 2025-01-13 23:21:04 +0100