[PATCH 3/5] memcg: teach uncharge_list to uncharge kmem pages

[Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>]

Page table pages are batched-freed in release_pages on most
architectures. If we want to charge them to kmemcg (this is what is done
later in this series), we need to teach mem_cgroup_uncharge_list to
handle kmem pages. With PageKmem helper introduced previously this is
trivial.

Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
---
 mm/memcontrol.c | 21 ++++++++++++++-------
 mm/swap.c       |  3 +--
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6ddaeba34e09..a61fe1604f49 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5420,15 +5420,18 @@ void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg)
 
 static void uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
 			   unsigned long nr_anon, unsigned long nr_file,
-			   unsigned long nr_huge, struct page *dummy_page)
+			   unsigned long nr_huge, unsigned long nr_kmem,
+			   struct page *dummy_page)
 {
-	unsigned long nr_pages = nr_anon + nr_file;
+	unsigned long nr_pages = nr_anon + nr_file + nr_kmem;
 	unsigned long flags;
 
 	if (!mem_cgroup_is_root(memcg)) {
 		page_counter_uncharge(&memcg->memory, nr_pages);
 		if (do_swap_account)
 			page_counter_uncharge(&memcg->memsw, nr_pages);
+		if (nr_kmem)
+			page_counter_uncharge(&memcg->kmem, nr_kmem);
 		memcg_oom_recover(memcg);
 	}
 
@@ -5451,6 +5454,7 @@ static void uncharge_list(struct list_head *page_list)
 	unsigned long nr_anon = 0;
 	unsigned long nr_file = 0;
 	unsigned long nr_huge = 0;
+	unsigned long nr_kmem = 0;
 	unsigned long pgpgout = 0;
 	struct list_head *next;
 	struct page *page;
@@ -5477,19 +5481,22 @@ static void uncharge_list(struct list_head *page_list)
 		if (memcg != page->mem_cgroup) {
 			if (memcg) {
 				uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
-					       nr_huge, page);
-				pgpgout = nr_anon = nr_file = nr_huge = 0;
+					       nr_huge, nr_kmem, page);
+				pgpgout = nr_anon = nr_file =
+					nr_huge = nr_kmem = 0;
 			}
 			memcg = page->mem_cgroup;
 		}
 
-		if (PageTransHuge(page)) {
+		if (!PageKmem(page) && PageTransHuge(page)) {
 			nr_pages <<= compound_order(page);
 			VM_BUG_ON_PAGE(!PageTransHuge(page), page);
 			nr_huge += nr_pages;
 		}
 
-		if (PageAnon(page))
+		if (PageKmem(page))
+			nr_kmem += 1 << compound_order(page);
+		else if (PageAnon(page))
 			nr_anon += nr_pages;
 		else
 			nr_file += nr_pages;
@@ -5501,7 +5508,7 @@ static void uncharge_list(struct list_head *page_list)
 
 	if (memcg)
 		uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
-			       nr_huge, page);
+			       nr_huge, nr_kmem, page);
 }
 
 /**
diff --git a/mm/swap.c b/mm/swap.c
index 8d8d03118a18..983f692a47fd 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -64,8 +64,7 @@ static void __page_cache_release(struct page *page)
 		del_page_from_lru_list(page, lruvec, page_off_lru(page));
 		spin_unlock_irqrestore(&zone->lru_lock, flags);
 	}
-	if (!PageKmem(page))
-		mem_cgroup_uncharge(page);
+	mem_cgroup_uncharge(page);
 }
 
 static void __put_single_page(struct page *page)
-- 
2.1.4

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