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From:   Zi Yan <zi.yan@sent.com>
To:     linux-mm@kvack.org, Matthew Wilcox <willy@infradead.org>
Cc:     "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Roman Gushchin <guro@fb.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        Yang Shi <shy828301@gmail.com>,
        Michal Hocko <mhocko@kernel.org>,
        John Hubbard <jhubbard@nvidia.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        David Nellans <dnellans@nvidia.com>, Zi Yan <ziy@nvidia.com>
Subject: [RFC PATCH 2/6] mm: memcg: make memcg huge page split support any order split.
Date:   Wed, 11 Nov 2020 15:40:04 -0500
Message-Id: <20201111204008.21332-3-zi.yan@sent.com>
In-Reply-To: <20201111204008.21332-1-zi.yan@sent.com>
References: <20201111204008.21332-1-zi.yan@sent.com>
Reply-To: Zi Yan <ziy@nvidia.com>
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From: Zi Yan <ziy@nvidia.com>

It reads thp_nr_pages and splits to provided new_nr. It prepares for
upcoming changes to support split huge page to any lower order.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 include/linux/memcontrol.h | 5 +++--
 mm/huge_memory.c           | 2 +-
 mm/memcontrol.c            | 4 ++--
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 0f4dd7829fb2..b3bac79ceed6 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1105,7 +1105,7 @@ static inline void memcg_memory_event_mm(struct mm_st=
ruct *mm,
 }
=20
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-void mem_cgroup_split_huge_fixup(struct page *head);
+void mem_cgroup_split_huge_fixup(struct page *head, unsigned int new_nr);
 #endif
=20
 #else /* CONFIG_MEMCG */
@@ -1451,7 +1451,8 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t=
 *pgdat, int order,
 	return 0;
 }
=20
-static inline void mem_cgroup_split_huge_fixup(struct page *head)
+static inline void mem_cgroup_split_huge_fixup(struct page *head,
+					       unsigned int new_nr)
 {
 }
=20
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c4fead5ead31..f599f5b9bf7f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2429,7 +2429,7 @@ static void __split_huge_page(struct page *page, stru=
ct list_head *list,
 	lruvec =3D mem_cgroup_page_lruvec(head, pgdat);
=20
 	/* complete memcg works before add pages to LRU */
-	mem_cgroup_split_huge_fixup(head);
+	mem_cgroup_split_huge_fixup(head, 1);
=20
 	if (PageAnon(head) && PageSwapCache(head)) {
 		swp_entry_t entry =3D { .val =3D page_private(head) };
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 33f632689cee..e9705ba6bbcc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3247,7 +3247,7 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, si=
ze_t size)
  * Because tail pages are not marked as "used", set it. We're under
  * pgdat->lru_lock and migration entries setup in all page mappings.
  */
-void mem_cgroup_split_huge_fixup(struct page *head)
+void mem_cgroup_split_huge_fixup(struct page *head, unsigned int new_nr)
 {
 	struct mem_cgroup *memcg =3D page_memcg(head);
 	int i;
@@ -3255,7 +3255,7 @@ void mem_cgroup_split_huge_fixup(struct page *head)
 	if (mem_cgroup_disabled())
 		return;
=20
-	for (i =3D 1; i < thp_nr_pages(head); i++) {
+	for (i =3D new_nr; i < thp_nr_pages(head); i +=3D new_nr) {
 		css_get(&memcg->css);
 		head[i].memcg_data =3D (unsigned long)memcg;
 	}
--=20
2.28.0