Depending on CONFIG_VMAP_STACK and the THREAD_SIZE / PAGE_SIZE ratio
the space for task stacks can be allocated using __vmalloc_node_range(),
alloc_pages_node() and kmem_cache_alloc_node(). In the first and the
second cases page->mem_cgroup pointer is set, but in the third it's
not: memcg membership of a slab page should be determined using the
memcg_from_slab_page() function, which looks at
page->slab_cache->memcg_params.memcg . In this case, using
mod_memcg_page_state() (as in account_kernel_stack()) is incorrect:
page->mem_cgroup pointer is NULL even for pages charged to a non-root
memory cgroup.
In order to fix it, let's introduce a mod_memcg_obj_state() helper,
which takes a pointer to a kernel object as a first argument, uses
mem_cgroup_from_obj() to get a RCU-protected memcg pointer and
calls mod_memcg_state(). It allows to handle all possible
configurations (CONFIG_VMAP_STACK and various THREAD_SIZE/PAGE_SIZE
values) without spilling any memcg/kmem specifics into fork.c .
Signed-off-by: Roman Gushchin <guro@xxxxxx>
---
include/linux/memcontrol.h | 5 +++++
kernel/fork.c | 4 ++--
mm/memcontrol.c | 11 +++++++++++
3 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 24c50d004c46..1b4150ff64be 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -695,6 +695,7 @@ 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);
+void mod_memcg_obj_state(void *p, int idx, int val);
static inline void mod_lruvec_state(struct lruvec *lruvec,
enum node_stat_item idx, int val)
@@ -1123,6 +1124,10 @@ static inline void __mod_lruvec_slab_state(void *p, enum node_stat_item idx,
__mod_node_page_state(page_pgdat(page), idx, val);
}
+static inline void mod_memcg_obj_state(void *p, int idx, int val)
+{
+}
+
static inline
unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
gfp_t gfp_mask,
diff --git a/kernel/fork.c b/kernel/fork.c
index 4dad271ee28e..d8d1ccc7a40e 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -397,8 +397,8 @@ static void account_kernel_stack(struct task_struct *tsk, int account)
mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
THREAD_SIZE / 1024 * account);
- mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB,
- account * (THREAD_SIZE / 1024));
+ mod_memcg_obj_state(stack, MEMCG_KERNEL_STACK_KB,
+ account * (THREAD_SIZE / 1024));
}
}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 43010471621c..2bdc1ae5402a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -774,6 +774,17 @@ void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val)
rcu_read_unlock();
}
+void mod_memcg_obj_state(void *p, int idx, int val)
+{
+ struct mem_cgroup *memcg;
+
+ rcu_read_lock();
+ memcg = mem_cgroup_from_obj(p);
+ if (memcg)
+ mod_memcg_state(memcg, idx, val);
+ rcu_read_unlock();
+}
+
/**
* __count_memcg_events - account VM events in a cgroup
* @memcg: the memory cgroup
--
2.24.1
