[PATCH v2 00/20] vmw_balloon: compaction, shrinker, 64-bit, etc.

[PATCH v2 00/20] vmw_balloon: compaction, shrinker, 64-bit, etc.

[Nadav Amit]

This patch-set adds the following enhancements to the VMware balloon
driver:

1. Balloon compaction support.
2. Report the number of inflated/deflated ballooned pages through vmstat.
3. Memory shrinker to avoid balloon over-inflation (and OOM).
4. Support VMs with memory limit that is greater than 16TB.
5. Faster and more aggressive inflation.

To support compaction we wish to use the existing infrastructure.
However, we need to make slight adaptions for it. We add a new list
interface to balloon-compaction, which is more generic and efficient,
since it does not require as many IRQ save/restore operations. We leave
the old interface that is used by the virtio balloon.

Big parts of this patch-set are cleanup and documentation. Patches 1-13
simplify the balloon code, document its behavior and allow the balloon
code to run concurrently. The support for concurrency is required for
compaction and the shrinker interface.

For documentation we use the kernel-doc format. We are aware that the
balloon interface is not public, but following the kernel-doc format may
be useful one day.

v1->v2:	* Fix build error when THP is off (kbuild)
	* Fix build error on i386 (kbuild)

Cc: Xavier Deguillard <xdeguillard@vmware.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: linux-mm@kvack.org
Cc: virtualization@lists.linux-foundation.org

Nadav Amit (19):
  vmw_balloon: handle commands in a single function.
  vmw_balloon: unify commands tracing and stats
  vmw_balloon: merge send_lock and send_unlock path
  vmw_balloon: simplifying batch access
  vmw_balloon: remove sleeping allocations
  vmw_balloon: change batch/single lock abstractions
  vmw_balloon: treat all refused pages equally
  vmw_balloon: rename VMW_BALLOON_2M_SHIFT to VMW_BALLOON_2M_ORDER
  vmw_balloon: refactor change size from vmballoon_work
  vmw_balloon: simplify vmballoon_send_get_target()
  vmw_balloon: stats rework
  vmw_balloon: rework the inflate and deflate loops
  vmw_balloon: general style cleanup
  vmw_balloon: add reset stat
  mm/balloon_compaction: suppress allocation warnings
  mm/balloon_compaction: list interfaces
  vmw_balloon: compaction support
  vmw_balloon: memory shrinker
  vmw_balloon: split refused pages

Xavier Deguillard (1):
  vmw_balloon: support 64-bit memory limit

 drivers/misc/Kconfig               |    1 +
 drivers/misc/vmw_balloon.c         | 2196 +++++++++++++++++++---------
 include/linux/balloon_compaction.h |    4 +
 include/uapi/linux/magic.h         |    1 +
 mm/balloon_compaction.c            |  142 +-
 5 files changed, 1577 insertions(+), 767 deletions(-)

-- 
2.17.1

[PATCH v2 15/20] mm/balloon_compaction: suppress allocation warnings

[Nadav Amit]

There is no reason to print warnings when balloon page allocation fails.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Cc: linux-mm@kvack.org
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 mm/balloon_compaction.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index ef858d547e2d..a6c0efb3544f 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -22,7 +22,8 @@
 struct page *balloon_page_alloc(void)
 {
 	struct page *page = alloc_page(balloon_mapping_gfp_mask() |
-				       __GFP_NOMEMALLOC | __GFP_NORETRY);
+				       __GFP_NOMEMALLOC | __GFP_NORETRY |
+				       __GFP_NOWARN);
 	return page;
 }
 EXPORT_SYMBOL_GPL(balloon_page_alloc);
-- 
2.17.1

[PATCH v2 16/20] mm/balloon_compaction: list interfaces

[Nadav Amit]

Introduce interfaces for ballooning enqueueing and dequeueing of a list
of pages. These interfaces reduce the overhead of storing and restoring
IRQs by batching the operations. In addition they do not panic if the
list of pages is empty.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: linux-mm@kvack.org
Cc: virtualization@lists.linux-foundation.org
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 include/linux/balloon_compaction.h |   4 +
 mm/balloon_compaction.c            | 139 +++++++++++++++++++++--------
 2 files changed, 105 insertions(+), 38 deletions(-)

diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
index 53051f3d8f25..2c5a8e09e413 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -72,6 +72,10 @@ extern struct page *balloon_page_alloc(void);
 extern void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,
 				 struct page *page);
 extern struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info);
+extern void balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
+				      struct list_head *pages);
+extern int balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info,
+				     struct list_head *pages, int n_req_pages);
 
 static inline void balloon_devinfo_init(struct balloon_dev_info *balloon)
 {
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index a6c0efb3544f..b920c2a10d6f 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -10,6 +10,100 @@
 #include <linux/export.h>
 #include <linux/balloon_compaction.h>
 
+static int balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
+				     struct page *page)
+{
+	/*
+	 * Block others from accessing the 'page' when we get around to
+	 * establishing additional references. We should be the only one
+	 * holding a reference to the 'page' at this point.
+	 */
+	if (!trylock_page(page)) {
+		WARN_ONCE(1, "balloon inflation failed to enqueue page\n");
+		return -EFAULT;
+	}
+	list_del(&page->lru);
+	balloon_page_insert(b_dev_info, page);
+	unlock_page(page);
+	__count_vm_event(BALLOON_INFLATE);
+	return 0;
+}
+
+/**
+ * balloon_page_list_enqueue() - inserts a list of pages into the balloon page
+ *				 list.
+ * @b_dev_info: balloon device descriptor where we will insert a new page to
+ * @pages: pages to enqueue - allocated using balloon_page_alloc.
+ *
+ * Driver must call it to properly enqueue a balloon pages before definitively
+ * removing it from the guest system.
+ */
+void balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
+			       struct list_head *pages)
+{
+	struct page *page, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+	list_for_each_entry_safe(page, tmp, pages, lru)
+		balloon_page_enqueue_one(b_dev_info, page);
+	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+}
+EXPORT_SYMBOL_GPL(balloon_page_list_enqueue);
+
+/**
+ * balloon_page_list_dequeue() - removes pages from balloon's page list and
+ *				 returns a list of the pages.
+ * @b_dev_info: balloon device decriptor where we will grab a page from.
+ * @pages: pointer to the list of pages that would be returned to the caller.
+ * @n_req_pages: number of requested pages.
+ *
+ * Driver must call it to properly de-allocate a previous enlisted balloon pages
+ * before definetively releasing it back to the guest system. This function
+ * tries to remove @n_req_pages from the ballooned pages and return it to the
+ * caller in the @pages list.
+ *
+ * Note that this function may fail to dequeue some pages temporarily empty due
+ * to compaction isolated pages.
+ *
+ * Return: number of pages that were added to the @pages list.
+ */
+int balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info,
+			       struct list_head *pages, int n_req_pages)
+{
+	struct page *page, *tmp;
+	unsigned long flags;
+	int n_pages = 0;
+
+	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+	list_for_each_entry_safe(page, tmp, &b_dev_info->pages, lru) {
+		/*
+		 * Block others from accessing the 'page' while we get around
+		 * establishing additional references and preparing the 'page'
+		 * to be released by the balloon driver.
+		 */
+		if (!trylock_page(page))
+			continue;
+
+		if (IS_ENABLED(CONFIG_BALLOON_COMPACTION) &&
+		    PageIsolated(page)) {
+			/* raced with isolation */
+			unlock_page(page);
+			continue;
+		}
+		balloon_page_delete(page);
+		__count_vm_event(BALLOON_DEFLATE);
+		unlock_page(page);
+		list_add(&page->lru, pages);
+		if (++n_pages >= n_req_pages)
+			break;
+	}
+	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+
+	return n_pages;
+}
+EXPORT_SYMBOL_GPL(balloon_page_list_dequeue);
+
 /*
  * balloon_page_alloc - allocates a new page for insertion into the balloon
  *			  page list.
@@ -44,17 +138,9 @@ void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,
 {
 	unsigned long flags;
 
-	/*
-	 * Block others from accessing the 'page' when we get around to
-	 * establishing additional references. We should be the only one
-	 * holding a reference to the 'page' at this point.
-	 */
-	BUG_ON(!trylock_page(page));
 	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
-	balloon_page_insert(b_dev_info, page);
-	__count_vm_event(BALLOON_INFLATE);
+	balloon_page_enqueue_one(b_dev_info, page);
 	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
-	unlock_page(page);
 }
 EXPORT_SYMBOL_GPL(balloon_page_enqueue);
 
@@ -71,36 +157,13 @@ EXPORT_SYMBOL_GPL(balloon_page_enqueue);
  */
 struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
 {
-	struct page *page, *tmp;
 	unsigned long flags;
-	bool dequeued_page;
+	LIST_HEAD(pages);
+	int n_pages;
 
-	dequeued_page = false;
-	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
-	list_for_each_entry_safe(page, tmp, &b_dev_info->pages, lru) {
-		/*
-		 * Block others from accessing the 'page' while we get around
-		 * establishing additional references and preparing the 'page'
-		 * to be released by the balloon driver.
-		 */
-		if (trylock_page(page)) {
-#ifdef CONFIG_BALLOON_COMPACTION
-			if (PageIsolated(page)) {
-				/* raced with isolation */
-				unlock_page(page);
-				continue;
-			}
-#endif
-			balloon_page_delete(page);
-			__count_vm_event(BALLOON_DEFLATE);
-			unlock_page(page);
-			dequeued_page = true;
-			break;
-		}
-	}
-	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+	n_pages = balloon_page_list_dequeue(b_dev_info, &pages, 1);
 
-	if (!dequeued_page) {
+	if (n_pages != 1) {
 		/*
 		 * If we are unable to dequeue a balloon page because the page
 		 * list is empty and there is no isolated pages, then something
@@ -113,9 +176,9 @@ struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
 			     !b_dev_info->isolated_pages))
 			BUG();
 		spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
-		page = NULL;
+		return NULL;
 	}
-	return page;
+	return list_first_entry(&pages, struct page, lru);
 }
 EXPORT_SYMBOL_GPL(balloon_page_dequeue);
 
-- 
2.17.1

Re: [PATCH v2 00/20] vmw_balloon: compaction, shrinker, 64-bit, etc.

[Greg Kroah-Hartman]

On Thu, Sep 20, 2018 at 10:30:06AM -0700, Nadav Amit wrote:
> This patch-set adds the following enhancements to the VMware balloon
> driver:
> 
> 1. Balloon compaction support.
> 2. Report the number of inflated/deflated ballooned pages through vmstat.
> 3. Memory shrinker to avoid balloon over-inflation (and OOM).
> 4. Support VMs with memory limit that is greater than 16TB.
> 5. Faster and more aggressive inflation.
> 
> To support compaction we wish to use the existing infrastructure.
> However, we need to make slight adaptions for it. We add a new list
> interface to balloon-compaction, which is more generic and efficient,
> since it does not require as many IRQ save/restore operations. We leave
> the old interface that is used by the virtio balloon.
> 
> Big parts of this patch-set are cleanup and documentation. Patches 1-13
> simplify the balloon code, document its behavior and allow the balloon
> code to run concurrently. The support for concurrency is required for
> compaction and the shrinker interface.
> 
> For documentation we use the kernel-doc format. We are aware that the
> balloon interface is not public, but following the kernel-doc format may
> be useful one day.

I applied the first 16 patches.  Please fix up 17 and resend.

thanks,

greg k-h

Re: [PATCH v2 00/20] vmw_balloon: compaction, shrinker, 64-bit, etc.

[Nadav Amit]

at 11:15 AM, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:

> On Thu, Sep 20, 2018 at 10:30:06AM -0700, Nadav Amit wrote:
>> This patch-set adds the following enhancements to the VMware balloon
>> driver:
>> 
>> 1. Balloon compaction support.
>> 2. Report the number of inflated/deflated ballooned pages through vmstat.
>> 3. Memory shrinker to avoid balloon over-inflation (and OOM).
>> 4. Support VMs with memory limit that is greater than 16TB.
>> 5. Faster and more aggressive inflation.
>> 
>> To support compaction we wish to use the existing infrastructure.
>> However, we need to make slight adaptions for it. We add a new list
>> interface to balloon-compaction, which is more generic and efficient,
>> since it does not require as many IRQ save/restore operations. We leave
>> the old interface that is used by the virtio balloon.
>> 
>> Big parts of this patch-set are cleanup and documentation. Patches 1-13
>> simplify the balloon code, document its behavior and allow the balloon
>> code to run concurrently. The support for concurrency is required for
>> compaction and the shrinker interface.
>> 
>> For documentation we use the kernel-doc format. We are aware that the
>> balloon interface is not public, but following the kernel-doc format may
>> be useful one day.
> 
> I applied the first 16 patches.  Please fix up 17 and resend.

Thanks. I will update it and resend later today.

Regards,
Nadav