[RFC PATCH 11/11] mm: Add free page notification hook

[Alexander Duyck <alexander.duyck@gmail.com>]

From: Alexander Duyck <alexander.h.duyck@linux.intel.com>

Add a hook so that we are notified when a new page is available. We will
use this hook to notify the virtio aeration system when we have achieved
enough free higher-order pages to justify the process of pulling some pages
and hinting on them.

Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 arch/x86/include/asm/page.h |   11 +++++++++++
 include/linux/gfp.h         |    4 ++++
 mm/page_alloc.c             |    2 ++
 3 files changed, 17 insertions(+)

diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 7555b48803a8..dfd546230120 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -18,6 +18,17 @@
 
 struct page;
 
+#ifdef CONFIG_AERATION
+#include <linux/memory_aeration.h>
+
+#define HAVE_ARCH_FREE_PAGE_NOTIFY
+static inline void
+arch_free_page_notify(struct page *page, struct zone *zone, int order)
+{
+	aerator_notify_free(page, zone, order);
+}
+
+#endif
 #include <linux/range.h>
 extern struct range pfn_mapped[];
 extern int nr_pfn_mapped;
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 407a089d861f..d975e7eabbf8 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -459,6 +459,10 @@ static inline struct zonelist *node_zonelist(int nid, gfp_t flags)
 #ifndef HAVE_ARCH_FREE_PAGE
 static inline void arch_free_page(struct page *page, int order) { }
 #endif
+#ifndef HAVE_ARCH_FREE_PAGE_NOTIFY
+static inline void
+arch_free_page_notify(struct page *page, struct zone *zone, int order) { }
+#endif
 #ifndef HAVE_ARCH_ALLOC_PAGE
 static inline void arch_alloc_page(struct page *page, int order) { }
 #endif
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e3800221414b..104763034ce3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -999,6 +999,8 @@ static inline void __free_one_page(struct page *page,
 		add_to_free_area_tail(page, area, migratetype);
 	else
 		add_to_free_area(page, area, migratetype);
+
+	arch_free_page_notify(page, zone, order);
 }
 
 /*