From 867e5e1de14b2b2bde324cdfeec3f3f83eb21424 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Sat, 30 Nov 2019 17:55:34 -0800 Subject: mm: clean up and clarify lruvec lookup procedure There is a per-memcg lruvec and a NUMA node lruvec. Which one is being used is somewhat confusing right now, and it's easy to make mistakes - especially when it comes to global reclaim. How it works: when memory cgroups are enabled, we always use the root_mem_cgroup's per-node lruvecs. When memory cgroups are not compiled in or disabled at runtime, we use pgdat->lruvec. Document that in a comment. Due to the way the reclaim code is generalized, all lookups use the mem_cgroup_lruvec() helper function, and nobody should have to find the right lruvec manually right now. But to avoid future mistakes, rename the pgdat->lruvec member to pgdat->__lruvec and delete the convenience wrapper that suggests it's a commonly accessed member. While in this area, swap the mem_cgroup_lruvec() argument order. The name suggests a memcg operation, yet it takes a pgdat first and a memcg second. I have to double take every time I call this. Fix that. Link: http://lkml.kernel.org/r/20191022144803.302233-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Acked-by: Michal Hocko Reviewed-by: Shakeel Butt Cc: Roman Gushchin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slab.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/slab.h') diff --git a/mm/slab.h b/mm/slab.h index 8b77f973a6ab..7e94700aa78c 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -369,7 +369,7 @@ static __always_inline int memcg_charge_slab(struct page *page, if (ret) goto out; - lruvec = mem_cgroup_lruvec(page_pgdat(page), memcg); + lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page)); mod_lruvec_state(lruvec, cache_vmstat_idx(s), 1 << order); /* transer try_charge() page references to kmem_cache */ @@ -393,7 +393,7 @@ static __always_inline void memcg_uncharge_slab(struct page *page, int order, rcu_read_lock(); memcg = READ_ONCE(s->memcg_params.memcg); if (likely(!mem_cgroup_is_root(memcg))) { - lruvec = mem_cgroup_lruvec(page_pgdat(page), memcg); + lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page)); mod_lruvec_state(lruvec, cache_vmstat_idx(s), -(1 << order)); memcg_kmem_uncharge_memcg(page, order, memcg); } else { -- cgit