diff options
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 103 |
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; |