[PATCH v3 0/4] Make balloon drivers memory changes known to the rest of the kernel

[PATCH v3 0/4] Make balloon drivers memory changes known to the rest of the kernel

[Alexander Atanasov]

Currently balloon drivers (Virtio,XEN, HyperV, VMWare, ...)
inflate and deflate the guest memory size but there is no
way to know how much the memory size is changed by them.

A common use of the ballooning is to emulate [1]
hot plug and hot unplug - due to the complexity of the later.
Hotplug has a notifier and one can also check the updated
memory size.

To improve this add InflatedTotal and InflatedFree
to /proc/meminfo and implement a balloon notifier.

Amount of inflated memory can be used:
 - si_meminfo(..) users can improve calculations
 - adjust cache/buffer sizes
 - adjust object/connection limits
 - as a hint for the oom a killer
 - by user space software that monitors memory pressure

Patches for the other balloon drivers will be done next.

Alexander Atanasov (4):
  Make place for common balloon code
  Enable balloon drivers to report inflated memory
  Display inflated memory to users
  drivers: virtio: balloon - update inflated memory

 Documentation/filesystems/proc.rst            |  6 +++
 MAINTAINERS                                   |  4 +-
 arch/powerpc/platforms/pseries/cmm.c          |  2 +-
 drivers/misc/vmw_balloon.c                    |  2 +-
 drivers/virtio/virtio_balloon.c               |  7 +++-
 fs/proc/meminfo.c                             | 10 +++++
 .../linux/{balloon_compaction.h => balloon.h} | 30 ++++++++++----
 mm/Makefile                                   |  2 +-
 mm/{balloon_compaction.c => balloon.c}        | 40 +++++++++++++++++--
 mm/migrate.c                                  |  1 -
 mm/vmscan.c                                   |  1 -
 11 files changed, 87 insertions(+), 18 deletions(-)
 rename include/linux/{balloon_compaction.h => balloon.h} (86%)
 rename mm/{balloon_compaction.c => balloon.c} (88%)

v2:
 - reworked from simple /proc/meminfo addition
v3:
 - added missed EXPORT_SYMBOLS
Reported-by: kernel test robot <lkp@intel.com>
 - instead of balloon_common.h just use balloon.h (yes, naming is hard)
 - cleaned up balloon.h - remove from files that do not use it and
   remove externs from function declarations

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: pv-drivers@vmware.com
Cc: Jason Wang <jasowang@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: linux-hyperv@vger.kernel.org
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: xen-devel@lists.xenproject.org

base-commit: 1c23f9e627a7b412978b4e852793c5e3c3efc555
-- 
2.31.1

[PATCH v3 0/4] Make balloon drivers memory changes known to the rest of the kernel

[Alexander Atanasov]

Currently balloon drivers (Virtio,XEN, HyperV, VMWare, ...)
inflate and deflate the guest memory size but there is no
way to know how much the memory size is changed by them.

A common use of the ballooning is to emulate [1]
hot plug and hot unplug - due to the complexity of the later.
Hotplug has a notifier and one can also check the updated
memory size.

To improve this add InflatedTotal and InflatedFree
to /proc/meminfo and implement a balloon notifier.

Amount of inflated memory can be used:
 - si_meminfo(..) users can improve calculations
 - adjust cache/buffer sizes
 - adjust object/connection limits
 - as a hint for the oom a killer
 - by user space software that monitors memory pressure

Patches for the other balloon drivers will be done next.

Alexander Atanasov (4):
  Make place for common balloon code
  Enable balloon drivers to report inflated memory
  Display inflated memory to users
  drivers: virtio: balloon - update inflated memory

 Documentation/filesystems/proc.rst            |  6 +++
 MAINTAINERS                                   |  4 +-
 arch/powerpc/platforms/pseries/cmm.c          |  2 +-
 drivers/misc/vmw_balloon.c                    |  2 +-
 drivers/virtio/virtio_balloon.c               |  7 +++-
 fs/proc/meminfo.c                             | 10 +++++
 .../linux/{balloon_compaction.h => balloon.h} | 30 ++++++++++----
 mm/Makefile                                   |  2 +-
 mm/{balloon_compaction.c => balloon.c}        | 40 +++++++++++++++++--
 mm/migrate.c                                  |  1 -
 mm/vmscan.c                                   |  1 -
 11 files changed, 87 insertions(+), 18 deletions(-)
 rename include/linux/{balloon_compaction.h => balloon.h} (86%)
 rename mm/{balloon_compaction.c => balloon.c} (88%)

v2:
 - reworked from simple /proc/meminfo addition
v3:
 - added missed EXPORT_SYMBOLS
Reported-by: kernel test robot <lkp@intel.com>
 - instead of balloon_common.h just use balloon.h (yes, naming is hard)
 - cleaned up balloon.h - remove from files that do not use it and
   remove externs from function declarations

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: pv-drivers@vmware.com
Cc: Jason Wang <jasowang@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: linux-hyperv@vger.kernel.org
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: xen-devel@lists.xenproject.org

base-commit: 1c23f9e627a7b412978b4e852793c5e3c3efc555
-- 
2.31.1

[PATCH v3 1/4] Make place for common balloon code

[Alexander Atanasov]

mm/balloon_compaction.c -> mm/balloon.c
File already contains code that is common along balloon
drivers so rename it to reflect its contents.

include/linux/balloon_compaction.h -> include/linux/balloon.h
Remove it from files which do not actually use it.
Drop externs from function delcarations.

Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
---
 MAINTAINERS                                       |  4 ++--
 arch/powerpc/platforms/pseries/cmm.c              |  2 +-
 drivers/misc/vmw_balloon.c                        |  2 +-
 drivers/virtio/virtio_balloon.c                   |  2 +-
 include/linux/{balloon_compaction.h => balloon.h} | 12 +++++-------
 mm/Makefile                                       |  2 +-
 mm/{balloon_compaction.c => balloon.c}            |  4 +---
 mm/migrate.c                                      |  1 -
 mm/vmscan.c                                       |  1 -
 9 files changed, 12 insertions(+), 18 deletions(-)
 rename include/linux/{balloon_compaction.h => balloon.h} (93%)
 rename mm/{balloon_compaction.c => balloon.c} (99%)

diff --git a/MAINTAINERS b/MAINTAINERS
index 9d7f64dc0efe..98d6ff5f226d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21494,8 +21494,8 @@ L:	virtualization@lists.linux-foundation.org
 S:	Maintained
 F:	drivers/virtio/virtio_balloon.c
 F:	include/uapi/linux/virtio_balloon.h
-F:	include/linux/balloon_compaction.h
-F:	mm/balloon_compaction.c
+F:	include/linux/balloon.h
+F:	mm/balloon.c
 
 VIRTIO CRYPTO DRIVER
 M:	Gonglei <arei.gonglei@huawei.com>
diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
index 5f4037c1d7fe..1d40f6416d6a 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -19,7 +19,7 @@
 #include <linux/stringify.h>
 #include <linux/swap.h>
 #include <linux/device.h>
-#include <linux/balloon_compaction.h>
+#include <linux/balloon.h>
 #include <asm/firmware.h>
 #include <asm/hvcall.h>
 #include <asm/mmu.h>
diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 61a2be712bf7..91d4d2a285c5 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -29,7 +29,7 @@
 #include <linux/rwsem.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
-#include <linux/balloon_compaction.h>
+#include <linux/balloon.h>
 #include <linux/vmw_vmci_defs.h>
 #include <linux/vmw_vmci_api.h>
 #include <asm/hypervisor.h>
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 3f78a3a1eb75..d0c27c680721 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -13,7 +13,7 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/module.h>
-#include <linux/balloon_compaction.h>
+#include <linux/balloon.h>
 #include <linux/oom.h>
 #include <linux/wait.h>
 #include <linux/mm.h>
diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon.h
similarity index 93%
rename from include/linux/balloon_compaction.h
rename to include/linux/balloon.h
index 5ca2d5699620..46ac8f61f607 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon.h
@@ -1,7 +1,5 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
- * include/linux/balloon_compaction.h
- *
  * Common interface definitions for making balloon pages movable by compaction.
  *
  * Balloon page migration makes use of the general non-lru movable page
@@ -59,13 +57,13 @@ struct balloon_dev_info {
 			struct page *page, enum migrate_mode mode);
 };
 
-extern struct page *balloon_page_alloc(void);
-extern void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,
+struct page *balloon_page_alloc(void);
+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 size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
+struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info);
+size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
 				      struct list_head *pages);
-extern size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info,
+size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info,
 				     struct list_head *pages, size_t n_req_pages);
 
 static inline void balloon_devinfo_init(struct balloon_dev_info *balloon)
diff --git a/mm/Makefile b/mm/Makefile
index 9a564f836403..550cb0663f50 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -112,7 +112,7 @@ obj-$(CONFIG_ZSMALLOC)	+= zsmalloc.o
 obj-$(CONFIG_Z3FOLD)	+= z3fold.o
 obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
 obj-$(CONFIG_CMA)	+= cma.o
-obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
+obj-$(CONFIG_MEMORY_BALLOON) += balloon.o
 obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
 obj-$(CONFIG_PAGE_TABLE_CHECK) += page_table_check.o
 obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
diff --git a/mm/balloon_compaction.c b/mm/balloon.c
similarity index 99%
rename from mm/balloon_compaction.c
rename to mm/balloon.c
index 22c96fed70b5..22b3e876bc78 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon.c
@@ -1,7 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * mm/balloon_compaction.c
- *
  * Common interface for making balloon pages movable by compaction.
  *
  * Copyright (C) 2012, Red Hat, Inc.  Rafael Aquini <aquini@redhat.com>
@@ -9,7 +7,7 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/export.h>
-#include <linux/balloon_compaction.h>
+#include <linux/balloon.h>
 
 static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
 				     struct page *page)
diff --git a/mm/migrate.c b/mm/migrate.c
index 6a1597c92261..a4c8bb334dde 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -41,7 +41,6 @@
 #include <linux/pfn_t.h>
 #include <linux/memremap.h>
 #include <linux/userfaultfd_k.h>
-#include <linux/balloon_compaction.h>
 #include <linux/page_idle.h>
 #include <linux/page_owner.h>
 #include <linux/sched/mm.h>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b2b1431352dc..f21d65b0d2e2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -54,7 +54,6 @@
 #include <asm/div64.h>
 
 #include <linux/swapops.h>
-#include <linux/balloon_compaction.h>
 #include <linux/sched/sysctl.h>
 
 #include "internal.h"
-- 
2.31.1

[PATCH v3 1/4] Make place for common balloon code

[Alexander Atanasov]

mm/balloon_compaction.c -> mm/balloon.c
File already contains code that is common along balloon
drivers so rename it to reflect its contents.

include/linux/balloon_compaction.h -> include/linux/balloon.h
Remove it from files which do not actually use it.
Drop externs from function delcarations.

Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
---
 MAINTAINERS                                       |  4 ++--
 arch/powerpc/platforms/pseries/cmm.c              |  2 +-
 drivers/misc/vmw_balloon.c                        |  2 +-
 drivers/virtio/virtio_balloon.c                   |  2 +-
 include/linux/{balloon_compaction.h => balloon.h} | 12 +++++-------
 mm/Makefile                                       |  2 +-
 mm/{balloon_compaction.c => balloon.c}            |  4 +---
 mm/migrate.c                                      |  1 -
 mm/vmscan.c                                       |  1 -
 9 files changed, 12 insertions(+), 18 deletions(-)
 rename include/linux/{balloon_compaction.h => balloon.h} (93%)
 rename mm/{balloon_compaction.c => balloon.c} (99%)

diff --git a/MAINTAINERS b/MAINTAINERS
index 9d7f64dc0efe..98d6ff5f226d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21494,8 +21494,8 @@ L:	virtualization@lists.linux-foundation.org
 S:	Maintained
 F:	drivers/virtio/virtio_balloon.c
 F:	include/uapi/linux/virtio_balloon.h
-F:	include/linux/balloon_compaction.h
-F:	mm/balloon_compaction.c
+F:	include/linux/balloon.h
+F:	mm/balloon.c
 
 VIRTIO CRYPTO DRIVER
 M:	Gonglei <arei.gonglei@huawei.com>
diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
index 5f4037c1d7fe..1d40f6416d6a 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -19,7 +19,7 @@
 #include <linux/stringify.h>
 #include <linux/swap.h>
 #include <linux/device.h>
-#include <linux/balloon_compaction.h>
+#include <linux/balloon.h>
 #include <asm/firmware.h>
 #include <asm/hvcall.h>
 #include <asm/mmu.h>
diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 61a2be712bf7..91d4d2a285c5 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -29,7 +29,7 @@
 #include <linux/rwsem.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
-#include <linux/balloon_compaction.h>
+#include <linux/balloon.h>
 #include <linux/vmw_vmci_defs.h>
 #include <linux/vmw_vmci_api.h>
 #include <asm/hypervisor.h>
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 3f78a3a1eb75..d0c27c680721 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -13,7 +13,7 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/module.h>
-#include <linux/balloon_compaction.h>
+#include <linux/balloon.h>
 #include <linux/oom.h>
 #include <linux/wait.h>
 #include <linux/mm.h>
diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon.h
similarity index 93%
rename from include/linux/balloon_compaction.h
rename to include/linux/balloon.h
index 5ca2d5699620..46ac8f61f607 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon.h
@@ -1,7 +1,5 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
- * include/linux/balloon_compaction.h
- *
  * Common interface definitions for making balloon pages movable by compaction.
  *
  * Balloon page migration makes use of the general non-lru movable page
@@ -59,13 +57,13 @@ struct balloon_dev_info {
 			struct page *page, enum migrate_mode mode);
 };
 
-extern struct page *balloon_page_alloc(void);
-extern void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,
+struct page *balloon_page_alloc(void);
+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 size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
+struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info);
+size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
 				      struct list_head *pages);
-extern size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info,
+size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info,
 				     struct list_head *pages, size_t n_req_pages);
 
 static inline void balloon_devinfo_init(struct balloon_dev_info *balloon)
diff --git a/mm/Makefile b/mm/Makefile
index 9a564f836403..550cb0663f50 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -112,7 +112,7 @@ obj-$(CONFIG_ZSMALLOC)	+= zsmalloc.o
 obj-$(CONFIG_Z3FOLD)	+= z3fold.o
 obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
 obj-$(CONFIG_CMA)	+= cma.o
-obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
+obj-$(CONFIG_MEMORY_BALLOON) += balloon.o
 obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
 obj-$(CONFIG_PAGE_TABLE_CHECK) += page_table_check.o
 obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
diff --git a/mm/balloon_compaction.c b/mm/balloon.c
similarity index 99%
rename from mm/balloon_compaction.c
rename to mm/balloon.c
index 22c96fed70b5..22b3e876bc78 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon.c
@@ -1,7 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * mm/balloon_compaction.c
- *
  * Common interface for making balloon pages movable by compaction.
  *
  * Copyright (C) 2012, Red Hat, Inc.  Rafael Aquini <aquini@redhat.com>
@@ -9,7 +7,7 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/export.h>
-#include <linux/balloon_compaction.h>
+#include <linux/balloon.h>
 
 static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
 				     struct page *page)
diff --git a/mm/migrate.c b/mm/migrate.c
index 6a1597c92261..a4c8bb334dde 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -41,7 +41,6 @@
 #include <linux/pfn_t.h>
 #include <linux/memremap.h>
 #include <linux/userfaultfd_k.h>
-#include <linux/balloon_compaction.h>
 #include <linux/page_idle.h>
 #include <linux/page_owner.h>
 #include <linux/sched/mm.h>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b2b1431352dc..f21d65b0d2e2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -54,7 +54,6 @@
 #include <asm/div64.h>
 
 #include <linux/swapops.h>
-#include <linux/balloon_compaction.h>
 #include <linux/sched/sysctl.h>
 
 #include "internal.h"
-- 
2.31.1

[PATCH v3 2/4] Enable balloon drivers to report inflated memory

[Alexander Atanasov]

Add counters to be updated by the balloon drivers.
Create balloon notifier to propagate changes.

Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
---
 include/linux/balloon.h | 18 ++++++++++++++++++
 mm/balloon.c            | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/include/linux/balloon.h b/include/linux/balloon.h
index 46ac8f61f607..59657da77d95 100644
--- a/include/linux/balloon.h
+++ b/include/linux/balloon.h
@@ -57,6 +57,24 @@ struct balloon_dev_info {
 			struct page *page, enum migrate_mode mode);
 };
 
+extern atomic_long_t mem_balloon_inflated_total_kb;
+extern atomic_long_t mem_balloon_inflated_free_kb;
+
+void balloon_set_inflated_total(long inflated_kb);
+void balloon_set_inflated_free(long inflated_kb);
+
+#define BALLOON_CHANGED_TOTAL 0
+#define BALLOON_CHANGED_FREE  1
+
+int register_balloon_notifier(struct notifier_block *nb);
+void unregister_balloon_notifier(struct notifier_block *nb);
+
+#define balloon_notifier(fn, pri) ({						\
+	static struct notifier_block fn##_mem_nb __meminitdata =\
+		{ .notifier_call = fn, .priority = pri };			\
+	register_balloon_notifier(&fn##_mem_nb);				\
+})
+
 struct page *balloon_page_alloc(void);
 void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,
 				 struct page *page);
diff --git a/mm/balloon.c b/mm/balloon.c
index 22b3e876bc78..8e1d5855fef8 100644
--- a/mm/balloon.c
+++ b/mm/balloon.c
@@ -7,8 +7,44 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/export.h>
+#include <linux/notifier.h>
 #include <linux/balloon.h>
 
+atomic_long_t mem_balloon_inflated_total_kb = ATOMIC_LONG_INIT(0);
+atomic_long_t mem_balloon_inflated_free_kb = ATOMIC_LONG_INIT(0);
+SRCU_NOTIFIER_HEAD_STATIC(balloon_chain);
+
+int register_balloon_notifier(struct notifier_block *nb)
+{
+	return srcu_notifier_chain_register(&balloon_chain, nb);
+}
+EXPORT_SYMBOL(register_balloon_notifier);
+
+void unregister_balloon_notifier(struct notifier_block *nb)
+{
+	srcu_notifier_chain_unregister(&balloon_chain, nb);
+}
+EXPORT_SYMBOL(unregister_balloon_notifier);
+
+static int balloon_notify(unsigned long val)
+{
+	return srcu_notifier_call_chain(&balloon_chain, val, NULL);
+}
+
+void balloon_set_inflated_total(long inflated_kb)
+{
+	atomic_long_set(&mem_balloon_inflated_total_kb, inflated_kb);
+	balloon_notify(BALLOON_CHANGED_TOTAL);
+}
+EXPORT_SYMBOL(balloon_set_inflated_total);
+
+void balloon_set_inflated_free(long inflated_kb)
+{
+	atomic_long_set(&mem_balloon_inflated_free_kb, inflated_kb);
+	balloon_notify(BALLOON_CHANGED_FREE);
+}
+EXPORT_SYMBOL(balloon_set_inflated_free);
+
 static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
 				     struct page *page)
 {
-- 
2.31.1

[PATCH v3 3/4] Display inflated memory to users

[Alexander Atanasov]

Add InflatedTotal and InflatedFree to /proc/meminfo

Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
---
 Documentation/filesystems/proc.rst |  6 ++++++
 fs/proc/meminfo.c                  | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index e7aafc82be99..690e1b90ffee 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -991,6 +991,8 @@ Example output. You may not have all of these fields.
     VmallocUsed:       40444 kB
     VmallocChunk:          0 kB
     Percpu:            29312 kB
+    InflatedTotal:   2097152 kB
+    InflatedFree:          0 kB
     HardwareCorrupted:     0 kB
     AnonHugePages:   4149248 kB
     ShmemHugePages:        0 kB
@@ -1138,6 +1140,10 @@ VmallocChunk
 Percpu
               Memory allocated to the percpu allocator used to back percpu
               allocations. This stat excludes the cost of metadata.
+InflatedTotal and InflatedFree
+               Amount of memory that is inflated by the balloon driver.
+               Due to differences among the drivers inflated memory
+               is subtracted from TotalRam or from MemFree.
 HardwareCorrupted
               The amount of RAM/memory in KB, the kernel identifies as
               corrupted.
diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index 6e89f0e2fd20..7182886efdbf 100644
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -16,6 +16,9 @@
 #ifdef CONFIG_CMA
 #include <linux/cma.h>
 #endif
+#ifdef CONFIG_MEMORY_BALLOON
+#include <linux/balloon.h>
+#endif
 #include <asm/page.h>
 #include "internal.h"
 
@@ -153,6 +156,13 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 		    global_zone_page_state(NR_FREE_CMA_PAGES));
 #endif
 
+#ifdef CONFIG_MEMORY_BALLOON
+	seq_printf(m,  "InflatedTotal:  %8ld kB\n",
+		atomic_long_read(&mem_balloon_inflated_total_kb));
+	seq_printf(m,  "InflatedFree:   %8ld kB\n",
+		atomic_long_read(&mem_balloon_inflated_free_kb));
+#endif
+
 	hugetlb_report_meminfo(m);
 
 	arch_report_meminfo(m);
-- 
2.31.1

[PATCH v3 4/4] drivers: virtio: balloon - update inflated memory

[Alexander Atanasov]

Update the inflated memory when it changes.

Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
---
 drivers/virtio/virtio_balloon.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index d0c27c680721..e9c3642eef17 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -450,10 +450,15 @@ static void virtballoon_changed(struct virtio_device *vdev)
 static void update_balloon_size(struct virtio_balloon *vb)
 {
 	u32 actual = vb->num_pages;
+	long inflated_kb = actual << (VIRTIO_BALLOON_PFN_SHIFT - 10);
 
 	/* Legacy balloon config space is LE, unlike all other devices. */
 	virtio_cwrite_le(vb->vdev, struct virtio_balloon_config, actual,
 			 &actual);
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
+		balloon_set_inflated_free(inflated_kb);
+	else
+		balloon_set_inflated_total(inflated_kb);
 }
 
 static void update_balloon_stats_func(struct work_struct *work)
-- 
2.31.1

Re: [PATCH v3 1/4] Make place for common balloon code

[Nadav Amit]

On Aug 22, 2022, at 4:37 AM, Alexander Atanasov <alexander.atanasov@virtuozzo.com> wrote:

> mm/balloon_compaction.c -> mm/balloon.c
> File already contains code that is common along balloon
> drivers so rename it to reflect its contents.
> 
> include/linux/balloon_compaction.h -> include/linux/balloon.h
> Remove it from files which do not actually use it.
> Drop externs from function delcarations.
> 
> Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>

Makes so much sense.

Acked-by: Nadav Amit <namit@vmware.com>

Re: [PATCH v3 1/4] Make place for common balloon code

[Nadav Amit via Virtualization]

On Aug 22, 2022, at 4:37 AM, Alexander Atanasov <alexander.atanasov@virtuozzo.com> wrote:

> mm/balloon_compaction.c -> mm/balloon.c
> File already contains code that is common along balloon
> drivers so rename it to reflect its contents.
> 
> include/linux/balloon_compaction.h -> include/linux/balloon.h
> Remove it from files which do not actually use it.
> Drop externs from function delcarations.
> 
> Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>

Makes so much sense.

Acked-by: Nadav Amit <namit@vmware.com>


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Re: [PATCH v3 1/4] Make place for common balloon code

[Nadav Amit]

On Aug 22, 2022, at 4:37 AM, Alexander Atanasov <alexander.atanasov@virtuozzo.com> wrote:

> mm/balloon_compaction.c -> mm/balloon.c
> File already contains code that is common along balloon
> drivers so rename it to reflect its contents.
> 
> include/linux/balloon_compaction.h -> include/linux/balloon.h
> Remove it from files which do not actually use it.
> Drop externs from function delcarations.
> 
> Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>

Makes so much sense.

Acked-by: Nadav Amit <namit@vmware.com>