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virtio-balloon: Revert "virtio-balloon: Switch back to OOM handler for VIRTIO_BALLOON_F_DEFLATE_ON_OOM" 

This reverts commit 5a6b4cc5b7.

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

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2020-04-07 05:43:30 -04:00
parent c9b9f5f8c0
commit 835a6a649d
1 changed files with 63 additions and 44 deletions
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107
drivers/virtio/virtio_balloon.c
View File

@ -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.
*/
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);