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Commit 9f3e1512 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux 

Pull virtio updates from Rusty Russell:
 "A balloon enhancement, and a minor race-on-module-unload theoretical
  bug which doesn't merit cc: stable.

  All the exciting stuff went via MST this cycle"

* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  virtio_balloon: free some memory from balloon on OOM
  virtio_balloon: return the amount of freed memory from leak_balloon()
  virtio_blk: fix race at module removal
  virtio: Fix comment typo 'CONFIG_S_FAILED'
parents 2efda904 5a10b7db

drivers/virtio/virtio_balloon.c

+56 −1
Original line number Diff line number Diff line
@@ -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 = {

include/linux/virtio.h

+1 −1
Original line number Diff line number Diff line
@@ -81,7 +81,7 @@ void *virtqueue_get_used(struct virtqueue *vq); 
/**

 * virtio_device - representation of a device using virtio

 * @index: unique position on the virtio bus

 * @failed: saved value for CONFIG_S_FAILED bit (for restore)

 * @failed: saved value for VIRTIO_CONFIG_S_FAILED bit (for restore)

 * @config_enabled: configuration change reporting enabled

 * @config_change_pending: configuration change reported while disabled

 * @config_lock: protects configuration change reporting

include/uapi/linux/virtio_balloon.h

+1 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
/* The feature bitmap for virtio balloon */

#define VIRTIO_BALLOON_F_MUST_TELL_HOST	0 /* Tell before reclaiming pages */

#define VIRTIO_BALLOON_F_STATS_VQ	1 /* Memory Stats virtqueue */

#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM	2 /* Deflate balloon on OOM */



/* Size of a PFN in the balloon interface. */

#define VIRTIO_BALLOON_PFN_SHIFT 12