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mm: workingset: fix vmstat counters for shadow nodes

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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 4d96ba3530 ("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 68d48e6a2d ("mm: workingset: add vmstat counter
for shadow nodes").

Link: http://lkml.kernel.org/r/20190801233532.138743-1-guro@fb.com
Fixes: 4d96ba3530 ("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>
This commit is contained in:
Roman Gushchin 2019-08-13 15:37:41 -07:00 committed by Linus Torvalds
parent 951531691c
commit ec9f02384f
3 changed files with 43 additions and 6 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

19
include/linux/memcontrol.h
View file

@ -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)

20
mm/memcontrol.c
View file

@ -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

10
mm/workingset.c
View file

@ -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);