From: Roman Gushchin <guro@xxxxxx>
Subject: 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@xxxxxx
Fixes: 4d96ba353075 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 19 +++++++++++++++++++
mm/memcontrol.c | 20 ++++++++++++++++++++
mm/workingset.c | 10 ++++------
3 files changed, 43 insertions(+), 6 deletions(-)
--- a/include/linux/memcontrol.h~mm-workingset-fix-vmstat-counters-for-shadow-nodes
+++ a/include/linux/memcontrol.h
@@ -668,6 +668,7 @@ static inline unsigned long lruvec_page_
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
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_sta
__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)
--- a/mm/memcontrol.c~mm-workingset-fix-vmstat-counters-for-shadow-nodes
+++ a/mm/memcontrol.c
@@ -768,6 +768,26 @@ void __mod_lruvec_state(struct lruvec *l
__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
--- a/mm/workingset.c~mm-workingset-fix-vmstat-counters-for-shadow-nodes
+++ a/mm/workingset.c
@@ -380,14 +380,12 @@ void workingset_update_node(struct xa_no
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_isolat
}
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_isolat
* 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);
_
