diff options
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 110 |
1 files changed, 59 insertions, 51 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index d97d73c73303..d1c1f6283729 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -27,7 +27,6 @@ #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> @@ -40,13 +39,8 @@ */ #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 @@ -86,8 +80,8 @@ struct virtio_balloon { /* 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[] = { @@ -365,38 +359,6 @@ static void update_balloon_size(struct virtio_balloon *vb) &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; @@ -550,6 +512,52 @@ static struct file_system_type balloon_fs = { #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; @@ -580,17 +588,10 @@ static int virtballoon_probe(struct virtio_device *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; } @@ -599,12 +600,19 @@ static int virtballoon_probe(struct virtio_device *vdev) 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); 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)) @@ -636,8 +644,8 @@ static void virtballoon_remove(struct virtio_device *vdev) { 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); |