Commit 56161634 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe

memcg: add mem_cgroup_root_css

Add global mem_cgroup_root_css which points to the root memcg css.
This will be used by cgroup writeback support.  If memcg is disabled,
it's defined as ERR_PTR(-EINVAL).
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
aCc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent ec13b1d6
......@@ -68,6 +68,8 @@ enum mem_cgroup_events_index {
};
#ifdef CONFIG_MEMCG
extern struct cgroup_subsys_state *mem_cgroup_root_css;
void mem_cgroup_events(struct mem_cgroup *memcg,
enum mem_cgroup_events_index idx,
unsigned int nr);
......@@ -196,6 +198,8 @@ void mem_cgroup_split_huge_fixup(struct page *head);
#else /* CONFIG_MEMCG */
struct mem_cgroup;
#define mem_cgroup_root_css ((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))
static inline void mem_cgroup_events(struct mem_cgroup *memcg,
enum mem_cgroup_events_index idx,
unsigned int nr)
......
......@@ -77,6 +77,7 @@ EXPORT_SYMBOL(memory_cgrp_subsys);
#define MEM_CGROUP_RECLAIM_RETRIES 5
static struct mem_cgroup *root_mem_cgroup __read_mostly;
struct cgroup_subsys_state *mem_cgroup_root_css __read_mostly;
/* Whether the swap controller is active */
#ifdef CONFIG_MEMCG_SWAP
......@@ -4441,6 +4442,7 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
/* root ? */
if (parent_css == NULL) {
root_mem_cgroup = memcg;
mem_cgroup_root_css = &memcg->css;
page_counter_init(&memcg->memory, NULL);
memcg->high = PAGE_COUNTER_MAX;
memcg->soft_limit = PAGE_COUNTER_MAX;
......
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