Anonymous compound pages can be mapped by ptes, which means that if we want to track NR_MAPPED_ANON, NR_ANON_THPS on a per-cgroup basis, we have to be prepared to see tail pages in our accounting functions.
Make mod_lruvec_page_state() and lock_page_memcg() deal with tail pages correctly, namely by redirecting to the head page which has the page->mem_cgroup set up. Signed-off-by: Johannes Weiner <[email protected]> Reviewed-by: Joonsoo Kim <[email protected]> --- include/linux/memcontrol.h | 5 +++-- mm/memcontrol.c | 9 ++++++--- 2 files changed, 9 insertions(+), 5 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 57339514d960..5b110ac7dd83 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -723,16 +723,17 @@ static inline void mod_lruvec_state(struct lruvec *lruvec, static inline void __mod_lruvec_page_state(struct page *page, enum node_stat_item idx, int val) { + struct page *head = compound_head(page); /* rmap on tail pages */ pg_data_t *pgdat = page_pgdat(page); struct lruvec *lruvec; /* Untracked pages have no memcg, no lruvec. Update only the node */ - if (!page->mem_cgroup) { + if (!head->mem_cgroup) { __mod_node_page_state(pgdat, idx, val); return; } - lruvec = mem_cgroup_lruvec(page->mem_cgroup, pgdat); + lruvec = mem_cgroup_lruvec(head->mem_cgroup, pgdat); __mod_lruvec_state(lruvec, idx, val); } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index fe4212db8411..b7be4cd6ddc5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1979,6 +1979,7 @@ void mem_cgroup_print_oom_group(struct mem_cgroup *memcg) */ struct mem_cgroup *lock_page_memcg(struct page *page) { + struct page *head = compound_head(page); /* rmap on tail pages */ struct mem_cgroup *memcg; unsigned long flags; @@ -1998,7 +1999,7 @@ struct mem_cgroup *lock_page_memcg(struct page *page) if (mem_cgroup_disabled()) return NULL; again: - memcg = page->mem_cgroup; + memcg = head->mem_cgroup; if (unlikely(!memcg)) return NULL; @@ -2006,7 +2007,7 @@ struct mem_cgroup *lock_page_memcg(struct page *page) return memcg; spin_lock_irqsave(&memcg->move_lock, flags); - if (memcg != page->mem_cgroup) { + if (memcg != head->mem_cgroup) { spin_unlock_irqrestore(&memcg->move_lock, flags); goto again; } @@ -2049,7 +2050,9 @@ void __unlock_page_memcg(struct mem_cgroup *memcg) */ void unlock_page_memcg(struct page *page) { - __unlock_page_memcg(page->mem_cgroup); + struct page *head = compound_head(page); + + __unlock_page_memcg(head->mem_cgroup); } EXPORT_SYMBOL(unlock_page_memcg); -- 2.26.2
