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 <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2e405e0..6f5c0c5 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