Re: [PATCH 5.6 086/126] virtio-balloon: Revert "virtio-balloon: Switch back to OOM handler for VIRTIO_BALLOON_F_DEFLATE_ON_OOM"

On Tue, May 26, 2020 at 08:53:43PM +0200, Greg Kroah-Hartman wrote:

From: Michael S. Tsirkin mst@redhat.com

[ Upstream commit 835a6a649d0dd1b1f46759eb60fff2f63ed253a7 ]

This reverts commit 5a6b4cc5b7a1892a8d7f63d6cbac6e0ae2a9d031.

It has been queued properly in the akpm tree, this version is just creating conflicts.

Signed-off-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org

I don't understand. How does this make sense in stable? stable does not merge akpm does it?

---

drivers/virtio/virtio_balloon.c | 107 +++++++++++++++++++------------- 1 file changed, 63 insertions(+), 44 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 44375a22307b..341458fd95ca 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -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;
• 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;

• 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.
  

•  */
  

• 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);
  

• }
• /*

• * 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; }

• 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);

-- 2.25.1