[PATCH -V9 [updated] 10/15] hugetlb/cgroup: Add the cgroup pointer to page lru

["Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>]

From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>

Add the hugetlb cgroup pointer to 3rd page lru.next. This limit
the usage to hugetlb cgroup to only hugepages with 3 or more
normal pages. I guess that is an acceptable limitation.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
 include/linux/hugetlb_cgroup.h |   37 +++++++++++++++++++++++++++++++++++++
 mm/hugetlb.c                   |    4 ++++
 2 files changed, 41 insertions(+)

diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
index e9944b4..2e4cb6b 100644
--- a/include/linux/hugetlb_cgroup.h
+++ b/include/linux/hugetlb_cgroup.h
@@ -18,8 +18,34 @@
 #include <linux/res_counter.h>
 
 struct hugetlb_cgroup;
+/*
+ * Minimum page order trackable by hugetlb cgroup.
+ * At least 3 pages are necessary for all the tracking information.
+ */
+#define HUGETLB_CGROUP_MIN_ORDER	2
 
 #ifdef CONFIG_CGROUP_HUGETLB_RES_CTLR
+
+static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
+{
+	VM_BUG_ON(!PageHuge(page));
+
+	if (compound_order(page) < HUGETLB_CGROUP_MIN_ORDER)
+		return NULL;
+	return (struct hugetlb_cgroup *)page[2].lru.next;
+}
+
+static inline
+int set_hugetlb_cgroup(struct page *page, struct hugetlb_cgroup *h_cg)
+{
+	VM_BUG_ON(!PageHuge(page));
+
+	if (compound_order(page) < HUGETLB_CGROUP_MIN_ORDER)
+		return -1;
+	page[2].lru.next = (void *)h_cg;
+	return 0;
+}
+
 static inline bool hugetlb_cgroup_disabled(void)
 {
 	if (hugetlb_subsys.disabled)
@@ -28,6 +54,17 @@ static inline bool hugetlb_cgroup_disabled(void)
 }
 
 #else
+static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
+{
+	return NULL;
+}
+
+static inline
+int set_hugetlb_cgroup(struct page *page, struct hugetlb_cgroup *h_cg)
+{
+	return 0;
+}
+
 static inline bool hugetlb_cgroup_disabled(void)
 {
 	return true;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e899a2d..6a449c5 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -28,6 +28,7 @@
 
 #include <linux/io.h>
 #include <linux/hugetlb.h>
+#include <linux/hugetlb_cgroup.h>
 #include <linux/node.h>
 #include "internal.h"
 
@@ -591,6 +592,7 @@ static void update_and_free_page(struct hstate *h, struct page *page)
 				1 << PG_active | 1 << PG_reserved |
 				1 << PG_private | 1 << PG_writeback);
 	}
+	VM_BUG_ON(hugetlb_cgroup_from_page(page));
 	set_compound_page_dtor(page, NULL);
 	set_page_refcounted(page);
 	arch_release_hugepage(page);
@@ -643,6 +645,7 @@ static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
 	INIT_LIST_HEAD(&page->lru);
 	set_compound_page_dtor(page, free_huge_page);
 	spin_lock(&hugetlb_lock);
+	set_hugetlb_cgroup(page, NULL);
 	h->nr_huge_pages++;
 	h->nr_huge_pages_node[nid]++;
 	spin_unlock(&hugetlb_lock);
@@ -892,6 +895,7 @@ static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
 		INIT_LIST_HEAD(&page->lru);
 		r_nid = page_to_nid(page);
 		set_compound_page_dtor(page, free_huge_page);
+		set_hugetlb_cgroup(page, NULL);
 		/*
 		 * We incremented the global counters already
 		 */
-- 
1.7.10

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