diff options
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 107 |
1 files changed, 63 insertions, 44 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 44375a22307b..341458fd95ca 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -14,7 +14,6 @@ #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> @@ -28,9 +27,7 @@ */ #define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT) #define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256 -/* 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 VIRTBALLOON_OOM_NOTIFY_PRIORITY 80 #define VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG (__GFP_NORETRY | __GFP_NOWARN | \ __GFP_NOMEMALLOC) @@ -115,11 +112,8 @@ struct virtio_balloon { /* Memory statistics */ struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; - /* Shrinker to return free pages - VIRTIO_BALLOON_F_FREE_PAGE_HINT */ + /* To register a shrinker to shrink memory upon memory pressure */ struct shrinker shrinker; - - /* OOM notifier to deflate on OOM - VIRTIO_BALLOON_F_DEFLATE_ON_OOM */ - struct notifier_block oom_nb; }; static struct virtio_device_id id_table[] = { @@ -794,13 +788,50 @@ 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); - return shrink_free_pages(vb, sc->nr_to_scan); + 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; } static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker, @@ -808,22 +839,26 @@ 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; + return count; } -static int virtio_balloon_oom_notify(struct notifier_block *nb, - unsigned long dummy, void *parm) +static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb) { - struct virtio_balloon *vb = container_of(nb, - struct virtio_balloon, oom_nb); - unsigned long *freed = parm; + unregister_shrinker(&vb->shrinker); +} - *freed += leak_balloon(vb, VIRTIO_BALLOON_OOM_NR_PAGES) / - VIRTIO_BALLOON_PAGES_PER_PAGE; - update_balloon_size(vb); +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 NOTIFY_OK; + return register_shrinker(&vb->shrinker); } static int virtballoon_probe(struct virtio_device *vdev) @@ -900,35 +935,22 @@ static int virtballoon_probe(struct virtio_device *vdev) virtio_cwrite(vb->vdev, struct virtio_balloon_config, poison_val, &poison_val); } - - /* - * We're allowed to reuse any free pages, even if they are - * still to be processed by the host. - */ - vb->shrinker.scan_objects = virtio_balloon_shrinker_scan; - vb->shrinker.count_objects = virtio_balloon_shrinker_count; - vb->shrinker.seeks = DEFAULT_SEEKS; - err = register_shrinker(&vb->shrinker); + } + /* + * 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; } - if (virtio_has_feature(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; - } - virtio_device_ready(vdev); if (towards_target(vb)) virtballoon_changed(vdev); return 0; -out_unregister_shrinker: - if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) - unregister_shrinker(&vb->shrinker); out_del_balloon_wq: if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) destroy_workqueue(vb->balloon_wq); @@ -967,11 +989,8 @@ static void virtballoon_remove(struct virtio_device *vdev) { struct virtio_balloon *vb = vdev->priv; - if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) - unregister_oom_notifier(&vb->oom_nb); - if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) - unregister_shrinker(&vb->shrinker); - + 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); |