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'

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'
Linus Torvalds
2 parents 2efda9042d 5a10b7dbf9
Showing 3 changed files Side-by-side Diff
drivers/virtio/virtio_balloon.c
include/linux/virtio.h
include/uapi/linux/virtio_balloon.h
@@ -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
  
@@ -36,7 +37,13 @@
  */
 #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
 {
 	struct virtio_device *vdev;
@@ -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 = {
@@ -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
@@ -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
...	...	@@ -28,6 +28,7 @@
28	28	#include <linux/slab.h>
29	29	#include <linux/module.h>
30	30	#include <linux/balloon_compaction.h>
	31	+#include <linux/oom.h>
31	32
32	33	/*
33	34	* Balloon device works in 4K page units. So each page is pointed to by
34	35
...	...	@@ -36,7 +37,13 @@
36	37	*/
37	38	#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
38	39	#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
	40	+#define OOM_VBALLOON_DEFAULT_PAGES 256
	41	+#define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
39	42
	43	+static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES;
	44	+module_param(oom_pages, int, S_IRUSR \| S_IWUSR);
	45	+MODULE_PARM_DESC(oom_pages, "pages to free on OOM");
	46	+
40	47	struct virtio_balloon
41	48	{
42	49	struct virtio_device *vdev;
...	...	@@ -71,6 +78,9 @@
71	78	/* Memory statistics */
72	79	int need_stats_update;
73	80	struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
	81	+
	82	+ /* To register callback in oom notifier call chain */
	83	+ struct notifier_block nb;
74	84	};
75	85
76	86	static struct virtio_device_id id_table[] = {
77	87
...	...	@@ -168,8 +178,9 @@
168	178	}
169	179	}
170	180
171		-static void leak_balloon(struct virtio_balloon *vb, size_t num)
	181	+static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
172	182	{
	183	+ unsigned num_freed_pages;
173	184	struct page *page;
174	185	struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
175	186
...	...	@@ -186,6 +197,7 @@
186	197	vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
187	198	}
188	199
	200	+ num_freed_pages = vb->num_pfns;
189	201	/*
190	202	* Note that if
191	203	* virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
...	...	@@ -195,6 +207,7 @@
195	207	tell_host(vb, vb->deflate_vq);
196	208	mutex_unlock(&vb->balloon_lock);
197	209	release_pages_by_pfn(vb->pfns, vb->num_pfns);
	210	+ return num_freed_pages;
198	211	}
199	212
200	213	static inline void update_stat(struct virtio_balloon *vb, int idx,
...	...	@@ -287,6 +300,38 @@
287	300	&actual);
288	301	}
289	302
	303	+/*
	304	+ * virtballoon_oom_notify - release pages when system is under severe
	305	+ * memory pressure (called from out_of_memory())
	306	+ * @self : notifier block struct
	307	+ * @dummy: not used
	308	+ * @parm : returned - number of freed pages
	309	+ *
	310	+ * The balancing of memory by use of the virtio balloon should not cause
	311	+ * the termination of processes while there are pages in the balloon.
	312	+ * If virtio balloon manages to release some memory, it will make the
	313	+ * system return and retry the allocation that forced the OOM killer
	314	+ * to run.
	315	+ */
	316	+static int virtballoon_oom_notify(struct notifier_block *self,
	317	+ unsigned long dummy, void *parm)
	318	+{
	319	+ struct virtio_balloon *vb;
	320	+ unsigned long *freed;
	321	+ unsigned num_freed_pages;
	322	+
	323	+ vb = container_of(self, struct virtio_balloon, nb);
	324	+ if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
	325	+ return NOTIFY_OK;
	326	+
	327	+ freed = parm;
	328	+ num_freed_pages = leak_balloon(vb, oom_pages);
	329	+ update_balloon_size(vb);
	330	+ *freed += num_freed_pages;
	331	+
	332	+ return NOTIFY_OK;
	333	+}
	334	+
290	335	static int balloon(void *_vballoon)
291	336	{
292	337	struct virtio_balloon *vb = _vballoon;
...	...	@@ -443,6 +488,12 @@
443	488	if (err)
444	489	goto out_free_vb;
445	490
	491	+ vb->nb.notifier_call = virtballoon_oom_notify;
	492	+ vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
	493	+ err = register_oom_notifier(&vb->nb);
	494	+ if (err < 0)
	495	+ goto out_oom_notify;
	496	+
446	497	vb->thread = kthread_run(balloon, vb, "vballoon");
447	498	if (IS_ERR(vb->thread)) {
448	499	err = PTR_ERR(vb->thread);
...	...	@@ -452,6 +503,8 @@
452	503	return 0;
453	504
454	505	out_del_vqs:
	506	+ unregister_oom_notifier(&vb->nb);
	507	+out_oom_notify:
455	508	vdev->config->del_vqs(vdev);
456	509	out_free_vb:
457	510	kfree(vb);
...	...	@@ -476,6 +529,7 @@
476	529	{
477	530	struct virtio_balloon *vb = vdev->priv;
478	531
	532	+ unregister_oom_notifier(&vb->nb);
479	533	kthread_stop(vb->thread);
480	534	remove_common(vb);
481	535	kfree(vb);
...	...	@@ -515,6 +569,7 @@
515	569	static unsigned int features[] = {
516	570	VIRTIO_BALLOON_F_MUST_TELL_HOST,
517	571	VIRTIO_BALLOON_F_STATS_VQ,
	572	+ VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
518	573	};
519	574
520	575	static struct virtio_driver virtio_balloon_driver = {
...	...	@@ -81,7 +81,7 @@
81	81	/**
82	82	* virtio_device - representation of a device using virtio
83	83	* @index: unique position on the virtio bus
84		- * @failed: saved value for CONFIG_S_FAILED bit (for restore)
	84	+ * @failed: saved value for VIRTIO_CONFIG_S_FAILED bit (for restore)
85	85	* @config_enabled: configuration change reporting enabled
86	86	* @config_change_pending: configuration change reported while disabled
87	87	* @config_lock: protects configuration change reporting
...	...	@@ -31,6 +31,7 @@
31	31	/* The feature bitmap for virtio balloon */
32	32	#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
33	33	#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
	34	+#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
34	35
35	36	/* Size of a PFN in the balloon interface. */
36	37	#define VIRTIO_BALLOON_PFN_SHIFT 12