virtio-balloon: Revert "virtio-balloon: Switch back to OOM handler for... (835a6a64) · Commits · 戴 / test

drivers/virtio/virtio_balloon.c

+63 −44

Original line number	Diff line number	Diff line
		@@ -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;

		return vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
		count = vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE;
		count += 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.
		* We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a
		* shrinker needs to be registered to relieve memory pressure.
		*/
		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 (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);

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