mm/balloon_compaction: add vmstat counters and kpageflags bit

Always mark pages with PageBalloon even if balloon compaction is disabled
and expose this mark in /proc/kpageflags as KPF_BALLOON.

Also this patch adds three counters into /proc/vmstat: "balloon_inflate",
"balloon_deflate" and "balloon_migrate".  They accumulate balloon
activity.  Current size of balloon is (balloon_inflate - balloon_deflate)
pages.

All generic balloon code now gathered under option CONFIG_MEMORY_BALLOON.
It should be selected by ballooning driver which wants use this feature.
Currently virtio-balloon is the only user.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 21 insertions, 3 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index 0ceb8a567dab..1d1ae6b078fd 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -231,11 +231,16 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
         boolean
 
 #
+# support for memory balloon
+config MEMORY_BALLOON
+        boolean
+
+#
 # support for memory balloon compaction
 config BALLOON_COMPACTION
         bool "Allow for balloon memory compaction/migration"
         def_bool y
-        depends on COMPACTION && VIRTIO_BALLOON
+        depends on COMPACTION && MEMORY_BALLOON
         help
           Memory fragmentation introduced by ballooning might reduce
           significantly the number of 2MB contiguous memory blocks that can be
diff --git a/mm/Makefile b/mm/Makefile
index f8ed7ab417b1..1f534a7f0a71 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -16,7 +16,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o \
                            readahead.o swap.o truncate.o vmscan.o shmem.o \
                            util.o mmzone.o vmstat.o backing-dev.o \
                            mm_init.o mmu_context.o percpu.o slab_common.o \
-                           compaction.o balloon_compaction.o vmacache.o \
+                           compaction.o vmacache.o \
                            interval_tree.o list_lru.o workingset.o \
                            iov_iter.o debug.o $(mmu-y)
 
@@ -67,3 +67,4 @@ obj-$(CONFIG_ZBUD)	+= zbud.o
 obj-$(CONFIG_ZSMALLOC)  += zsmalloc.o
 obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
 obj-$(CONFIG_CMA)       += cma.o
+obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index 3afdabdbc0a4..b3cbe19f71b5 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -36,6 +36,7 @@ struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info)
         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);
         spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
         unlock_page(page);
         return page;
@@ -74,6 +75,7 @@ struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
                         }
                         spin_lock_irqsave(&b_dev_info->pages_lock, flags);
                         balloon_page_delete(page);
+                        __count_vm_event(BALLOON_DEFLATE);
                         spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
                         unlock_page(page);
                         dequeued_page = true;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index e9ab104b956f..cce7c766da7a 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -735,7 +735,7 @@ static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
                                         TEXT_FOR_HIGHMEM(xx) xx "_movable",
 
 const char * const vmstat_text[] = {
-        /* Zoned VM counters */
+        /* enum zone_stat_item countes */
         "nr_free_pages",
         "nr_alloc_batch",
         "nr_inactive_anon",
@@ -778,10 +778,13 @@ const char * const vmstat_text[] = {
         "workingset_nodereclaim",
         "nr_anon_transparent_hugepages",
         "nr_free_cma",
+
+        /* enum writeback_stat_item counters */
         "nr_dirty_threshold",
         "nr_dirty_background_threshold",
 
 #ifdef CONFIG_VM_EVENT_COUNTERS
+        /* enum vm_event_item counters */
         "pgpgin",
         "pgpgout",
         "pswpin",
@@ -860,6 +863,13 @@ const char * const vmstat_text[] = {
         "thp_zero_page_alloc",
         "thp_zero_page_alloc_failed",
 #endif
+#ifdef CONFIG_MEMORY_BALLOON
+        "balloon_inflate",
+        "balloon_deflate",
+#ifdef CONFIG_BALLOON_COMPACTION
+        "balloon_migrate",
+#endif
+#endif /* CONFIG_MEMORY_BALLOON */
 #ifdef CONFIG_DEBUG_TLBFLUSH
 #ifdef CONFIG_SMP
         "nr_tlb_remote_flush",