[PATCH -V7 08/14] hugetlbfs: add a list for tracking in-use HugeTLB pages

[Aneesh Kumar K.V]

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

hugepage_activelist will be used to track currently used HugeTLB pages.
We need to find the in-use HugeTLB pages to support memcg removal.  On
memcg removal we update the page's memory cgroup to point to parent
cgroup.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Hillf Danton <dhillf@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
---
 include/linux/hugetlb.h |    1 +
 mm/hugetlb.c            |   12 +++++++-----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index c21e136..c4353ea 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -211,6 +211,7 @@ struct hstate {
 	unsigned long resv_huge_pages;
 	unsigned long surplus_huge_pages;
 	unsigned long nr_overcommit_huge_pages;
+	struct list_head hugepage_activelist;
 	struct list_head hugepage_freelists[MAX_NUMNODES];
 	unsigned int nr_huge_pages_node[MAX_NUMNODES];
 	unsigned int free_huge_pages_node[MAX_NUMNODES];
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 704a269..0f38728 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -510,7 +510,7 @@ void copy_huge_page(struct page *dst, struct page *src)
 static void enqueue_huge_page(struct hstate *h, struct page *page)
 {
 	int nid = page_to_nid(page);
-	list_add(&page->lru, &h->hugepage_freelists[nid]);
+	list_move(&page->lru, &h->hugepage_freelists[nid]);
 	h->free_huge_pages++;
 	h->free_huge_pages_node[nid]++;
 }
@@ -522,7 +522,7 @@ static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
 	if (list_empty(&h->hugepage_freelists[nid]))
 		return NULL;
 	page = list_entry(h->hugepage_freelists[nid].next, struct page, lru);
-	list_del(&page->lru);
+	list_move(&page->lru, &h->hugepage_activelist);
 	set_page_refcounted(page);
 	h->free_huge_pages--;
 	h->free_huge_pages_node[nid]--;
@@ -626,10 +626,11 @@ static void free_huge_page(struct page *page)
 	page->mapping = NULL;
 	BUG_ON(page_count(page));
 	BUG_ON(page_mapcount(page));
-	INIT_LIST_HEAD(&page->lru);
 
 	spin_lock(&hugetlb_lock);
 	if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
+		/* remove the page from active list */
+		list_del(&page->lru);
 		update_and_free_page(h, page);
 		h->surplus_huge_pages--;
 		h->surplus_huge_pages_node[nid]--;
@@ -642,6 +643,7 @@ static void free_huge_page(struct page *page)
 
 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);
 	h->nr_huge_pages++;
@@ -890,6 +892,7 @@ static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
 
 	spin_lock(&hugetlb_lock);
 	if (page) {
+		INIT_LIST_HEAD(&page->lru);
 		r_nid = page_to_nid(page);
 		set_compound_page_dtor(page, free_huge_page);
 		/*
@@ -994,7 +997,6 @@ retry:
 	list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
 		if ((--needed) < 0)
 			break;
-		list_del(&page->lru);
 		/*
 		 * This page is now managed by the hugetlb allocator and has
 		 * no users -- drop the buddy allocator's reference.
@@ -1009,7 +1011,6 @@ free:
 	/* Free unnecessary surplus pages to the buddy allocator */
 	if (!list_empty(&surplus_list)) {
 		list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
-			list_del(&page->lru);
 			put_page(page);
 		}
 	}
@@ -1909,6 +1910,7 @@ void __init hugetlb_add_hstate(unsigned order)
 	h->free_huge_pages = 0;
 	for (i = 0; i < MAX_NUMNODES; ++i)
 		INIT_LIST_HEAD(&h->hugepage_freelists[i]);
+	INIT_LIST_HEAD(&h->hugepage_activelist);
 	h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]);
 	h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]);
 	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
-- 
1.7.10

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