diff options
Diffstat (limited to 'drivers/virtio')
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 57 |
1 files changed, 56 insertions, 1 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index c9703d4d6f6..50c5f42d7a9 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -28,6 +28,7 @@ #include <linux/slab.h> #include <linux/module.h> #include <linux/balloon_compaction.h> +#include <linux/oom.h> /* * Balloon device works in 4K page units. So each page is pointed to by @@ -36,6 +37,12 @@ */ #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"); struct virtio_balloon { @@ -71,6 +78,9 @@ struct virtio_balloon /* Memory statistics */ int need_stats_update; struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; + + /* To register callback in oom notifier call chain */ + struct notifier_block nb; }; static struct virtio_device_id id_table[] = { @@ -168,8 +178,9 @@ static void release_pages_by_pfn(const u32 pfns[], unsigned int num) } } -static void leak_balloon(struct virtio_balloon *vb, size_t num) +static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) { + unsigned num_freed_pages; struct page *page; struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; @@ -186,6 +197,7 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num) vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; } + num_freed_pages = vb->num_pfns; /* * Note that if * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); @@ -195,6 +207,7 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num) tell_host(vb, vb->deflate_vq); mutex_unlock(&vb->balloon_lock); release_pages_by_pfn(vb->pfns, vb->num_pfns); + return num_freed_pages; } static inline void update_stat(struct virtio_balloon *vb, int idx, @@ -287,6 +300,38 @@ 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 int balloon(void *_vballoon) { struct virtio_balloon *vb = _vballoon; @@ -443,6 +488,12 @@ 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_oom_notify; + vb->thread = kthread_run(balloon, vb, "vballoon"); if (IS_ERR(vb->thread)) { err = PTR_ERR(vb->thread); @@ -452,6 +503,8 @@ static int virtballoon_probe(struct virtio_device *vdev) return 0; out_del_vqs: + unregister_oom_notifier(&vb->nb); +out_oom_notify: vdev->config->del_vqs(vdev); out_free_vb: kfree(vb); @@ -476,6 +529,7 @@ static void virtballoon_remove(struct virtio_device *vdev) { struct virtio_balloon *vb = vdev->priv; + unregister_oom_notifier(&vb->nb); kthread_stop(vb->thread); remove_common(vb); kfree(vb); @@ -515,6 +569,7 @@ static int virtballoon_restore(struct virtio_device *vdev) static unsigned int features[] = { VIRTIO_BALLOON_F_MUST_TELL_HOST, VIRTIO_BALLOON_F_STATS_VQ, + VIRTIO_BALLOON_F_DEFLATE_ON_OOM, }; static struct virtio_driver virtio_balloon_driver = { |