From ec9f02384f6053f2a5417e82b65078edc5364a8d Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Tue, 13 Aug 2019 15:37:41 -0700 Subject: [PATCH] mm: workingset: fix vmstat counters for shadow nodes Memcg counters for shadow nodes are broken because the memcg pointer is obtained in a wrong way. The following approach is used: virt_to_page(xa_node)->mem_cgroup Since commit 4d96ba353075 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages") page->mem_cgroup pointer isn't set for slab pages, so memcg_from_slab_page() should be used instead. Also I doubt that it ever worked correctly: virt_to_head_page() should be used instead of virt_to_page(). Otherwise objects residing on tail pages are not accounted, because only the head page contains a valid mem_cgroup pointer. That was a case since the introduction of these counters by the commit 68d48e6a2df5 ("mm: workingset: add vmstat counter for shadow nodes"). Link: http://lkml.kernel.org/r/20190801233532.138743-1-guro@fb.com Fixes: 4d96ba353075 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages") Signed-off-by: Roman Gushchin Acked-by: Johannes Weiner Cc: Vladimir Davydov Cc: Shakeel Butt Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memcontrol.h | 19 +++++++++++++++++++ mm/memcontrol.c | 20 ++++++++++++++++++++ mm/workingset.c | 10 ++++------ 3 files changed, 43 insertions(+), 6 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 44c41462be33..2cd4359cb38c 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -668,6 +668,7 @@ static inline unsigned long lruvec_page_state_local(struct lruvec *lruvec, void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx, int val); +void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val); static inline void mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx, int val) @@ -1072,6 +1073,14 @@ static inline void mod_lruvec_page_state(struct page *page, mod_node_page_state(page_pgdat(page), idx, val); } +static inline void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, + int val) +{ + struct page *page = virt_to_head_page(p); + + __mod_node_page_state(page_pgdat(page), idx, val); +} + static inline unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, gfp_t gfp_mask, @@ -1159,6 +1168,16 @@ static inline void __dec_lruvec_page_state(struct page *page, __mod_lruvec_page_state(page, idx, -1); } +static inline void __inc_lruvec_slab_state(void *p, enum node_stat_item idx) +{ + __mod_lruvec_slab_state(p, idx, 1); +} + +static inline void __dec_lruvec_slab_state(void *p, enum node_stat_item idx) +{ + __mod_lruvec_slab_state(p, idx, -1); +} + /* idx can be of type enum memcg_stat_item or node_stat_item */ static inline void inc_memcg_state(struct mem_cgroup *memcg, int idx) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2e405e058eda..6f5c0c517c49 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -768,6 +768,26 @@ void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx, __this_cpu_write(pn->lruvec_stat_cpu->count[idx], x); } +void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val) +{ + struct page *page = virt_to_head_page(p); + pg_data_t *pgdat = page_pgdat(page); + struct mem_cgroup *memcg; + struct lruvec *lruvec; + + rcu_read_lock(); + memcg = memcg_from_slab_page(page); + + /* Untracked pages have no memcg, no lruvec. Update only the node */ + if (!memcg || memcg == root_mem_cgroup) { + __mod_node_page_state(pgdat, idx, val); + } else { + lruvec = mem_cgroup_lruvec(pgdat, memcg); + __mod_lruvec_state(lruvec, idx, val); + } + rcu_read_unlock(); +} + /** * __count_memcg_events - account VM events in a cgroup * @memcg: the memory cgroup diff --git a/mm/workingset.c b/mm/workingset.c index e0b4edcb88c8..c963831d354f 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -380,14 +380,12 @@ void workingset_update_node(struct xa_node *node) if (node->count && node->count == node->nr_values) { if (list_empty(&node->private_list)) { list_lru_add(&shadow_nodes, &node->private_list); - __inc_lruvec_page_state(virt_to_page(node), - WORKINGSET_NODES); + __inc_lruvec_slab_state(node, WORKINGSET_NODES); } } else { if (!list_empty(&node->private_list)) { list_lru_del(&shadow_nodes, &node->private_list); - __dec_lruvec_page_state(virt_to_page(node), - WORKINGSET_NODES); + __dec_lruvec_slab_state(node, WORKINGSET_NODES); } } } @@ -480,7 +478,7 @@ static enum lru_status shadow_lru_isolate(struct list_head *item, } list_lru_isolate(lru, item); - __dec_lruvec_page_state(virt_to_page(node), WORKINGSET_NODES); + __dec_lruvec_slab_state(node, WORKINGSET_NODES); spin_unlock(lru_lock); @@ -503,7 +501,7 @@ static enum lru_status shadow_lru_isolate(struct list_head *item, * shadow entries we were tracking ... */ xas_store(&xas, NULL); - __inc_lruvec_page_state(virt_to_page(node), WORKINGSET_NODERECLAIM); + __inc_lruvec_slab_state(node, WORKINGSET_NODERECLAIM); out_invalid: xa_unlock_irq(&mapping->i_pages);