From: Johannes Weiner <hannes@xxxxxxxxxxx> 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@xxxxxxxxxxx Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/memcontrol.h | 24 ++++++++++++------------ include/linux/mmzone.h | 15 ++++++++------- mm/memcontrol.c | 10 +++++----- mm/page_alloc.c | 2 +- mm/slab.h | 4 ++-- mm/vmscan.c | 6 +++--- mm/workingset.c | 8 ++++---- 7 files changed, 35 insertions(+), 34 deletions(-) --- a/include/linux/memcontrol.h~mm-clean-up-and-clarify-lruvec-lookup-procedure +++ a/include/linux/memcontrol.h @@ -385,21 +385,21 @@ mem_cgroup_nodeinfo(struct mem_cgroup *m } /** - * mem_cgroup_lruvec - get the lru list vector for a node or a memcg zone - * @node: node of the wanted lruvec + * mem_cgroup_lruvec - get the lru list vector for a memcg & node * @memcg: memcg of the wanted lruvec * - * Returns the lru list vector holding pages for a given @node or a given - * @memcg. This can be the node lruvec, if the memory controller is disabled. + * Returns the lru list vector holding pages for a given @memcg & + * @node combination. This can be the node lruvec, if the memory + * controller is disabled. */ -static inline struct lruvec *mem_cgroup_lruvec(struct pglist_data *pgdat, - struct mem_cgroup *memcg) +static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg, + struct pglist_data *pgdat) { struct mem_cgroup_per_node *mz; struct lruvec *lruvec; if (mem_cgroup_disabled()) { - lruvec = node_lruvec(pgdat); + lruvec = &pgdat->__lruvec; goto out; } @@ -718,7 +718,7 @@ static inline void __mod_lruvec_page_sta return; } - lruvec = mem_cgroup_lruvec(pgdat, page->mem_cgroup); + lruvec = mem_cgroup_lruvec(page->mem_cgroup, pgdat); __mod_lruvec_state(lruvec, idx, val); } @@ -889,16 +889,16 @@ static inline void mem_cgroup_migrate(st { } -static inline struct lruvec *mem_cgroup_lruvec(struct pglist_data *pgdat, - struct mem_cgroup *memcg) +static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg, + struct pglist_data *pgdat) { - return node_lruvec(pgdat); + return &pgdat->__lruvec; } static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat) { - return &pgdat->lruvec; + return &pgdat->__lruvec; } static inline bool mm_match_cgroup(struct mm_struct *mm, --- a/include/linux/mmzone.h~mm-clean-up-and-clarify-lruvec-lookup-procedure +++ a/include/linux/mmzone.h @@ -777,7 +777,13 @@ typedef struct pglist_data { #endif /* Fields commonly accessed by the page reclaim scanner */ - struct lruvec lruvec; + + /* + * NOTE: THIS IS UNUSED IF MEMCG IS ENABLED. + * + * Use mem_cgroup_lruvec() to look up lruvecs. + */ + struct lruvec __lruvec; unsigned long flags; @@ -800,11 +806,6 @@ typedef struct pglist_data { #define node_start_pfn(nid) (NODE_DATA(nid)->node_start_pfn) #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid)) -static inline struct lruvec *node_lruvec(struct pglist_data *pgdat) -{ - return &pgdat->lruvec; -} - static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat) { return pgdat->node_start_pfn + pgdat->node_spanned_pages; @@ -842,7 +843,7 @@ static inline struct pglist_data *lruvec #ifdef CONFIG_MEMCG return lruvec->pgdat; #else - return container_of(lruvec, struct pglist_data, lruvec); + return container_of(lruvec, struct pglist_data, __lruvec); #endif } --- a/mm/memcontrol.c~mm-clean-up-and-clarify-lruvec-lookup-procedure +++ a/mm/memcontrol.c @@ -777,7 +777,7 @@ void __mod_lruvec_slab_state(void *p, en if (!memcg || memcg == root_mem_cgroup) { __mod_node_page_state(pgdat, idx, val); } else { - lruvec = mem_cgroup_lruvec(pgdat, memcg); + lruvec = mem_cgroup_lruvec(memcg, pgdat); __mod_lruvec_state(lruvec, idx, val); } rcu_read_unlock(); @@ -1221,7 +1221,7 @@ struct lruvec *mem_cgroup_page_lruvec(st struct lruvec *lruvec; if (mem_cgroup_disabled()) { - lruvec = &pgdat->lruvec; + lruvec = &pgdat->__lruvec; goto out; } @@ -3634,7 +3634,7 @@ static int mem_cgroup_move_charge_write( static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg, int nid, unsigned int lru_mask) { - struct lruvec *lruvec = mem_cgroup_lruvec(NODE_DATA(nid), memcg); + struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid)); unsigned long nr = 0; enum lru_list lru; @@ -5338,8 +5338,8 @@ static int mem_cgroup_move_account(struc anon = PageAnon(page); pgdat = page_pgdat(page); - from_vec = mem_cgroup_lruvec(pgdat, from); - to_vec = mem_cgroup_lruvec(pgdat, to); + from_vec = mem_cgroup_lruvec(from, pgdat); + to_vec = mem_cgroup_lruvec(to, pgdat); spin_lock_irqsave(&from->move_lock, flags); --- a/mm/page_alloc.c~mm-clean-up-and-clarify-lruvec-lookup-procedure +++ a/mm/page_alloc.c @@ -6713,7 +6713,7 @@ static void __meminit pgdat_init_interna pgdat_page_ext_init(pgdat); spin_lock_init(&pgdat->lru_lock); - lruvec_init(node_lruvec(pgdat)); + lruvec_init(&pgdat->__lruvec); } static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx, int nid, --- a/mm/slab.h~mm-clean-up-and-clarify-lruvec-lookup-procedure +++ a/mm/slab.h @@ -369,7 +369,7 @@ static __always_inline int memcg_charge_ 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_unchar 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 { --- a/mm/vmscan.c~mm-clean-up-and-clarify-lruvec-lookup-procedure +++ a/mm/vmscan.c @@ -2545,7 +2545,7 @@ out: static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memcg, struct scan_control *sc) { - struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); + struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat); unsigned long nr[NR_LRU_LISTS]; unsigned long targets[NR_LRU_LISTS]; unsigned long nr_to_scan; @@ -3023,7 +3023,7 @@ static void snapshot_refaults(struct mem unsigned long refaults; struct lruvec *lruvec; - lruvec = mem_cgroup_lruvec(pgdat, memcg); + lruvec = mem_cgroup_lruvec(memcg, pgdat); refaults = lruvec_page_state_local(lruvec, WORKINGSET_ACTIVATE); lruvec->refaults = refaults; } while ((memcg = mem_cgroup_iter(root_memcg, memcg, NULL))); @@ -3379,7 +3379,7 @@ static void age_active_anon(struct pglis memcg = mem_cgroup_iter(NULL, NULL, NULL); do { - struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); + struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat); if (inactive_list_is_low(lruvec, false, sc, true)) shrink_active_list(SWAP_CLUSTER_MAX, lruvec, --- a/mm/workingset.c~mm-clean-up-and-clarify-lruvec-lookup-procedure +++ a/mm/workingset.c @@ -233,7 +233,7 @@ void *workingset_eviction(struct page *p VM_BUG_ON_PAGE(page_count(page), page); VM_BUG_ON_PAGE(!PageLocked(page), page); - lruvec = mem_cgroup_lruvec(pgdat, memcg); + lruvec = mem_cgroup_lruvec(memcg, pgdat); eviction = atomic_long_inc_return(&lruvec->inactive_age); return pack_shadow(memcgid, pgdat, eviction, PageWorkingset(page)); } @@ -280,7 +280,7 @@ void workingset_refault(struct page *pag memcg = mem_cgroup_from_id(memcgid); if (!mem_cgroup_disabled() && !memcg) goto out; - lruvec = mem_cgroup_lruvec(pgdat, memcg); + lruvec = mem_cgroup_lruvec(memcg, pgdat); refault = atomic_long_read(&lruvec->inactive_age); active_file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES); @@ -345,7 +345,7 @@ void workingset_activation(struct page * memcg = page_memcg_rcu(page); if (!mem_cgroup_disabled() && !memcg) goto out; - lruvec = mem_cgroup_lruvec(page_pgdat(page), memcg); + lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page)); atomic_long_inc(&lruvec->inactive_age); out: rcu_read_unlock(); @@ -426,7 +426,7 @@ static unsigned long count_shadow_nodes( struct lruvec *lruvec; int i; - lruvec = mem_cgroup_lruvec(NODE_DATA(sc->nid), sc->memcg); + lruvec = mem_cgroup_lruvec(sc->memcg, NODE_DATA(sc->nid)); for (pages = 0, i = 0; i < NR_LRU_LISTS; i++) pages += lruvec_page_state_local(lruvec, NR_LRU_BASE + i); _
