[PATCH 2/2] hugetlb/cgroup: Assign the page hugetlb cgroup when we move the page to active list.

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

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

page's hugetlb cgroup assign and moving to active list should happen with
hugetlb_lock held. Otherwise when we remove the hugetlb cgroup we would
iterate the active list and will find page with NULL hugetlb cgroup values.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
 mm/hugetlb.c        |   12 +++++++-----
 mm/hugetlb_cgroup.c |    3 +--
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ee4da3b..b90dfb4 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1146,9 +1146,12 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
 	}
 	spin_lock(&hugetlb_lock);
 	page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
-	spin_unlock(&hugetlb_lock);
-
-	if (!page) {
+	if (page) {
+		/* update page cgroup details */
+		hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
+		spin_unlock(&hugetlb_lock);
+	} else {
+		spin_unlock(&hugetlb_lock);
 		page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
 		if (!page) {
 			hugetlb_cgroup_uncharge_cgroup(idx,
@@ -1159,14 +1162,13 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
 		}
 		spin_lock(&hugetlb_lock);
 		list_move(&page->lru, &h->hugepage_activelist);
+		hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
 		spin_unlock(&hugetlb_lock);
 	}
 
 	set_page_private(page, (unsigned long)spool);
 
 	vma_commit_reservation(h, vma, addr);
-	/* update page cgroup details */
-	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
 	return page;
 }
 
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index 8e7ca0a..d4f3f7b 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -218,6 +218,7 @@ done:
 	return ret;
 }
 
+/* Should be called with hugetlb_lock held */
 void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
 				  struct hugetlb_cgroup *h_cg,
 				  struct page *page)
@@ -225,9 +226,7 @@ void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
 	if (hugetlb_cgroup_disabled() || !h_cg)
 		return;
 
-	spin_lock(&hugetlb_lock);
 	set_hugetlb_cgroup(page, h_cg);
-	spin_unlock(&hugetlb_lock);
 	return;
 }
 
-- 
1.7.10

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