From: Greg Kroah-Hartman gregkh@linuxfoundation.org
This reverts commit 37681282be8e89ae8baf26753bf489837d74e08e which is commit 835a6a649d0dd1b1f46759eb60fff2f63ed253a7 upstream.
Jiri and David agree that it is not needed in the 5.6.y tree, so revert it.
Reported-by: Jiri Slaby jslaby@suse.cz Reported-by: David Hildenbrand david@redhat.com Cc: Michael S. Tsirkin mst@redhat.com Cc: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/virtio/virtio_balloon.c | 107 ++++++++++++++++------------------------ 1 file changed, 44 insertions(+), 63 deletions(-)
--- 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> @@ -27,7 +28,9 @@ */ #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) @@ -112,8 +115,11 @@ 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; };
static struct virtio_device_id id_table[] = { @@ -788,50 +794,13 @@ static unsigned long shrink_free_pages(s 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, @@ -839,26 +808,22 @@ static unsigned long virtio_balloon_shri { 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 count; + return vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES; }
-static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb) +static int virtio_balloon_oom_notify(struct notifier_block *nb, + unsigned long dummy, void *parm) { - unregister_shrinker(&vb->shrinker); -} + struct virtio_balloon *vb = container_of(nb, + struct virtio_balloon, oom_nb); + unsigned long *freed = parm;
-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; + *freed += leak_balloon(vb, VIRTIO_BALLOON_OOM_NR_PAGES) / + VIRTIO_BALLOON_PAGES_PER_PAGE; + update_balloon_size(vb);
- return register_shrinker(&vb->shrinker); + return NOTIFY_OK; }
static int virtballoon_probe(struct virtio_device *vdev) @@ -935,22 +900,35 @@ static int virtballoon_probe(struct virt 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); + + /* + * 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); 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); @@ -989,8 +967,11 @@ static void virtballoon_remove(struct vi { struct virtio_balloon *vb = vdev->priv;
- if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) - virtio_balloon_unregister_shrinker(vb); + 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); + spin_lock_irq(&vb->stop_update_lock); vb->stop_update = true; spin_unlock_irq(&vb->stop_update_lock);