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'
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index c9703d4..50c5f42 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 @@
/* 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 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 @@
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 @@
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 @@
&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 @@
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 @@
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 @@
{
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 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 = {
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index d09e093..28f0e65 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -81,7 +81,7 @@
/**
* 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
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 5e26f61..be40f70 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -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