#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>
*/
#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
-#define OOM_VBALLOON_DEFAULT_PAGES 256
#define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
-static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES;
-module_param(oom_pages, int, S_IRUSR | S_IWUSR);
-MODULE_PARM_DESC(oom_pages, "pages to free on OOM");
-
#ifdef CONFIG_BALLOON_COMPACTION
static struct vfsmount *balloon_mnt;
#endif
/* Memory statistics */
struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
- /* To register callback in oom notifier call chain */
- struct notifier_block nb;
+ /* To register a shrinker to shrink memory upon memory pressure */
+ struct shrinker shrinker;
};
static struct virtio_device_id id_table[] = {
&actual);
}
-/*
- * virtballoon_oom_notify - release pages when system is under severe
- * memory pressure (called from out_of_memory())
- * @self : notifier block struct
- * @dummy: not used
- * @parm : returned - number of freed pages
- *
- * The balancing of memory by use of the virtio balloon should not cause
- * the termination of processes while there are pages in the balloon.
- * If virtio balloon manages to release some memory, it will make the
- * system return and retry the allocation that forced the OOM killer
- * to run.
- */
-static int virtballoon_oom_notify(struct notifier_block *self,
- unsigned long dummy, void *parm)
-{
- struct virtio_balloon *vb;
- unsigned long *freed;
- unsigned num_freed_pages;
-
- vb = container_of(self, struct virtio_balloon, nb);
- if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
- return NOTIFY_OK;
-
- freed = parm;
- num_freed_pages = leak_balloon(vb, oom_pages);
- update_balloon_size(vb);
- *freed += num_freed_pages;
-
- return NOTIFY_OK;
-}
-
static void update_balloon_stats_func(struct work_struct *work)
{
struct virtio_balloon *vb;
num_stats = update_balloon_stats(vb);
sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
- if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)
- < 0)
- BUG();
+ err = virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb,
+ GFP_KERNEL);
+ if (err) {
+ dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",
+ __func__);
+ return err;
+ }
virtqueue_kick(vb->stats_vq);
}
return 0;
#endif /* CONFIG_BALLOON_COMPACTION */
+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 * VIRTIO_BALLOON_PAGES_PER_PAGE;
+
+ /*
+ * 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_to_free) {
+ pages_to_free -= pages_freed;
+ pages_freed += leak_balloon(vb, pages_to_free);
+ }
+ update_balloon_size(vb);
+
+ return pages_freed / VIRTIO_BALLOON_PAGES_PER_PAGE;
+}
+
+static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker,
+ struct shrink_control *sc)
+{
+ struct virtio_balloon *vb = container_of(shrinker,
+ struct virtio_balloon, shrinker);
+
+ return vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE;
+}
+
+static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb)
+{
+ unregister_shrinker(&vb->shrinker);
+}
+
+static int virtio_balloon_register_shrinker(struct virtio_balloon *vb)
+{
+ vb->shrinker.scan_objects = virtio_balloon_shrinker_scan;
+ vb->shrinker.count_objects = virtio_balloon_shrinker_count;
+ vb->shrinker.seeks = DEFAULT_SEEKS;
+
+ return register_shrinker(&vb->shrinker);
+}
+
static int virtballoon_probe(struct virtio_device *vdev)
{
struct virtio_balloon *vb;
return -EINVAL;
}
- vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
+ vdev->priv = vb = kzalloc(sizeof(*vb), GFP_KERNEL);
if (!vb) {
err = -ENOMEM;
goto out;
INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);
INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);
spin_lock_init(&vb->stop_update_lock);
- vb->stop_update = false;
- vb->num_pages = 0;
mutex_init(&vb->balloon_lock);
init_waitqueue_head(&vb->acked);
vb->vdev = vdev;
if (err)
goto out_free_vb;
- vb->nb.notifier_call = virtballoon_oom_notify;
- vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
- err = register_oom_notifier(&vb->nb);
- if (err < 0)
- goto out_del_vqs;
-
#ifdef CONFIG_BALLOON_COMPACTION
balloon_mnt = kern_mount(&balloon_fs);
if (IS_ERR(balloon_mnt)) {
err = PTR_ERR(balloon_mnt);
- unregister_oom_notifier(&vb->nb);
goto out_del_vqs;
}
if (IS_ERR(vb->vb_dev_info.inode)) {
err = PTR_ERR(vb->vb_dev_info.inode);
kern_unmount(balloon_mnt);
- unregister_oom_notifier(&vb->nb);
- vb->vb_dev_info.inode = NULL;
goto out_del_vqs;
}
vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops;
#endif
-
+ /*
+ * 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_vqs;
+ }
virtio_device_ready(vdev);
if (towards_target(vb))
{
struct virtio_balloon *vb = vdev->priv;
- unregister_oom_notifier(&vb->nb);
-
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
+ virtio_balloon_unregister_shrinker(vb);
spin_lock_irq(&vb->stop_update_lock);
vb->stop_update = true;
spin_unlock_irq(&vb->stop_update_lock);
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