memcg: export struct mem_cgroup

mem_cgroup structure is defined in mm/memcontrol.c currently which means
that the code outside of this file has to use external API even for
trivial access stuff.

This patch exports mm_struct with its dependencies and makes some of the
exported functions inlines.  This even helps to reduce the code size a bit
(make defconfig + CONFIG_MEMCG=y)

  text		data    bss     dec     	 hex 	filename
  12355346        1823792 1089536 15268674         e8fb42 vmlinux.before
  12354970        1823792 1089536 15268298         e8f9ca vmlinux.after

This is not much (370B) but better than nothing.

We also save a function call in some hot paths like callers of
mem_cgroup_count_vm_event which is used for accounting.

The patch doesn't introduce any functional changes.

[vdavykov@parallels.com: inline memcg_kmem_is_active]
[vdavykov@parallels.com: do not expose type outside of CONFIG_MEMCG]
[akpm@linux-foundation.org: memcontrol.h needs eventfd.h for eventfd_ctx]
[akpm@linux-foundation.org: export mem_cgroup_from_task() to modules]
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 346 insertions, 62 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 73b02b0a8f60..ab2f6880e27b 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -23,6 +23,11 @@
 #include <linux/vm_event_item.h>
 #include <linux/hardirq.h>
 #include <linux/jump_label.h>
+#include <linux/page_counter.h>
+#include <linux/vmpressure.h>
+#include <linux/eventfd.h>
+#include <linux/mmzone.h>
+#include <linux/writeback.h>
 
 struct mem_cgroup;
 struct page;
@@ -67,12 +72,221 @@ enum mem_cgroup_events_index {
 	MEMCG_NR_EVENTS,
 };
 
+/*
+ * Per memcg event counter is incremented at every pagein/pageout. With THP,
+ * it will be incremated by the number of pages. This counter is used for
+ * for trigger some periodic events. This is straightforward and better
+ * than using jiffies etc. to handle periodic memcg event.
+ */
+enum mem_cgroup_events_target {
+	MEM_CGROUP_TARGET_THRESH,
+	MEM_CGROUP_TARGET_SOFTLIMIT,
+	MEM_CGROUP_TARGET_NUMAINFO,
+	MEM_CGROUP_NTARGETS,
+};
+
+/*
+ * Bits in struct cg_proto.flags
+ */
+enum cg_proto_flags {
+	/* Currently active and new sockets should be assigned to cgroups */
+	MEMCG_SOCK_ACTIVE,
+	/* It was ever activated; we must disarm static keys on destruction */
+	MEMCG_SOCK_ACTIVATED,
+};
+
+struct cg_proto {
+	struct page_counter	memory_allocated;	/* Current allocated memory. */
+	struct percpu_counter	sockets_allocated;	/* Current number of sockets. */
+	int			memory_pressure;
+	long			sysctl_mem[3];
+	unsigned long		flags;
+	/*
+	 * memcg field is used to find which memcg we belong directly
+	 * Each memcg struct can hold more than one cg_proto, so container_of
+	 * won't really cut.
+	 *
+	 * The elegant solution would be having an inverse function to
+	 * proto_cgroup in struct proto, but that means polluting the structure
+	 * for everybody, instead of just for memcg users.
+	 */
+	struct mem_cgroup	*memcg;
+};
+
 #ifdef CONFIG_MEMCG
+struct mem_cgroup_stat_cpu {
+	long count[MEM_CGROUP_STAT_NSTATS];
+	unsigned long events[MEMCG_NR_EVENTS];
+	unsigned long nr_page_events;
+	unsigned long targets[MEM_CGROUP_NTARGETS];
+};
+
+struct mem_cgroup_reclaim_iter {
+	struct mem_cgroup *position;
+	/* scan generation, increased every round-trip */
+	unsigned int generation;
+};
+
+/*
+ * per-zone information in memory controller.
+ */
+struct mem_cgroup_per_zone {
+	struct lruvec		lruvec;
+	unsigned long		lru_size[NR_LRU_LISTS];
+
+	struct mem_cgroup_reclaim_iter	iter[DEF_PRIORITY + 1];
+
+	struct rb_node		tree_node;	/* RB tree node */
+	unsigned long		usage_in_excess;/* Set to the value by which */
+						/* the soft limit is exceeded*/
+	bool			on_tree;
+	struct mem_cgroup	*memcg;		/* Back pointer, we cannot */
+						/* use container_of	   */
+};
+
+struct mem_cgroup_per_node {
+	struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
+};
+
+struct mem_cgroup_threshold {
+	struct eventfd_ctx *eventfd;
+	unsigned long threshold;
+};
+
+/* For threshold */
+struct mem_cgroup_threshold_ary {
+	/* An array index points to threshold just below or equal to usage. */
+	int current_threshold;
+	/* Size of entries[] */
+	unsigned int size;
+	/* Array of thresholds */
+	struct mem_cgroup_threshold entries[0];
+};
+
+struct mem_cgroup_thresholds {
+	/* Primary thresholds array */
+	struct mem_cgroup_threshold_ary *primary;
+	/*
+	 * Spare threshold array.
+	 * This is needed to make mem_cgroup_unregister_event() "never fail".
+	 * It must be able to store at least primary->size - 1 entries.
+	 */
+	struct mem_cgroup_threshold_ary *spare;
+};
+
+/*
+ * The memory controller data structure. The memory controller controls both
+ * page cache and RSS per cgroup. We would eventually like to provide
+ * statistics based on the statistics developed by Rik Van Riel for clock-pro,
+ * to help the administrator determine what knobs to tune.
+ */
+struct mem_cgroup {
+	struct cgroup_subsys_state css;
+
+	/* Accounted resources */
+	struct page_counter memory;
+	struct page_counter memsw;
+	struct page_counter kmem;
+
+	/* Normal memory consumption range */
+	unsigned long low;
+	unsigned long high;
+
+	unsigned long soft_limit;
+
+	/* vmpressure notifications */
+	struct vmpressure vmpressure;
+
+	/* css_online() has been completed */
+	int initialized;
+
+	/*
+	 * Should the accounting and control be hierarchical, per subtree?
+	 */
+	bool use_hierarchy;
+
+	/* protected by memcg_oom_lock */
+	bool		oom_lock;
+	int		under_oom;
+
+	int	swappiness;
+	/* OOM-Killer disable */
+	int		oom_kill_disable;
+
+	/* protect arrays of thresholds */
+	struct mutex thresholds_lock;
+
+	/* thresholds for memory usage. RCU-protected */
+	struct mem_cgroup_thresholds thresholds;
+
+	/* thresholds for mem+swap usage. RCU-protected */
+	struct mem_cgroup_thresholds memsw_thresholds;
+
+	/* For oom notifier event fd */
+	struct list_head oom_notify;
+
+	/*
+	 * Should we move charges of a task when a task is moved into this
+	 * mem_cgroup ? And what type of charges should we move ?
+	 */
+	unsigned long move_charge_at_immigrate;
+	/*
+	 * set > 0 if pages under this cgroup are moving to other cgroup.
+	 */
+	atomic_t		moving_account;
+	/* taken only while moving_account > 0 */
+	spinlock_t		move_lock;
+	struct task_struct	*move_lock_task;
+	unsigned long		move_lock_flags;
+	/*
+	 * percpu counter.
+	 */
+	struct mem_cgroup_stat_cpu __percpu *stat;
+	spinlock_t pcp_counter_lock;
+
+#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
+	struct cg_proto tcp_mem;
+#endif
+#if defined(CONFIG_MEMCG_KMEM)
+        /* Index in the kmem_cache->memcg_params.memcg_caches array */
+	int kmemcg_id;
+	bool kmem_acct_activated;
+	bool kmem_acct_active;
+#endif
+
+	int last_scanned_node;
+#if MAX_NUMNODES > 1
+	nodemask_t	scan_nodes;
+	atomic_t	numainfo_events;
+	atomic_t	numainfo_updating;
+#endif
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+	struct list_head cgwb_list;
+	struct wb_domain cgwb_domain;
+#endif
+
+	/* List of events which userspace want to receive */
+	struct list_head event_list;
+	spinlock_t event_list_lock;
+
+	struct mem_cgroup_per_node *nodeinfo[0];
+	/* WARNING: nodeinfo must be the last member here */
+};
 extern struct cgroup_subsys_state *mem_cgroup_root_css;
 
-void mem_cgroup_events(struct mem_cgroup *memcg,
+/**
+ * mem_cgroup_events - count memory events against a cgroup
+ * @memcg: the memory cgroup
+ * @idx: the event index
+ * @nr: the number of events to account for
+ */
+static inline void mem_cgroup_events(struct mem_cgroup *memcg,
 		       enum mem_cgroup_events_index idx,
-		       unsigned int nr);
+		       unsigned int nr)
+{
+	this_cpu_add(memcg->stat->events[idx], nr);
+}
 
 bool mem_cgroup_low(struct mem_cgroup *root, struct mem_cgroup *memcg);
 
@@ -90,15 +304,31 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
 struct lruvec *mem_cgroup_zone_lruvec(struct zone *, struct mem_cgroup *);
 struct lruvec *mem_cgroup_page_lruvec(struct page *, struct zone *);
 
-bool mem_cgroup_is_descendant(struct mem_cgroup *memcg,
-			      struct mem_cgroup *root);
 bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg);
 
 extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
 extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
 
 extern struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg);
-extern struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css);
+static inline
+struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
+	return css ? container_of(css, struct mem_cgroup, css) : NULL;
+}
+
+struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *,
+				   struct mem_cgroup *,
+				   struct mem_cgroup_reclaim_cookie *);
+void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *);
+
+static inline bool mem_cgroup_is_descendant(struct mem_cgroup *memcg,
+			      struct mem_cgroup *root)
+{
+	if (root == memcg)
+		return true;
+	if (!root->use_hierarchy)
+		return false;
+	return cgroup_is_descendant(memcg->css.cgroup, root->css.cgroup);
+}
 
 static inline bool mm_match_cgroup(struct mm_struct *mm,
 				   struct mem_cgroup *memcg)
@@ -114,22 +344,65 @@ static inline bool mm_match_cgroup(struct mm_struct *mm,
 	return match;
 }
 
-extern struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg);
 extern struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page);
 
-struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *,
-				   struct mem_cgroup *,
-				   struct mem_cgroup_reclaim_cookie *);
-void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *);
+static inline bool mem_cgroup_disabled(void)
+{
+	if (memory_cgrp_subsys.disabled)
+		return true;
+	return false;
+}
 
 /*
  * For memory reclaim.
  */
-int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec);
-bool mem_cgroup_lruvec_online(struct lruvec *lruvec);
 int mem_cgroup_select_victim_node(struct mem_cgroup *memcg);
-unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list);
-void mem_cgroup_update_lru_size(struct lruvec *, enum lru_list, int);
+
+void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
+		int nr_pages);
+
+static inline bool mem_cgroup_lruvec_online(struct lruvec *lruvec)
+{
+	struct mem_cgroup_per_zone *mz;
+	struct mem_cgroup *memcg;
+
+	if (mem_cgroup_disabled())
+		return true;
+
+	mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
+	memcg = mz->memcg;
+
+	return !!(memcg->css.flags & CSS_ONLINE);
+}
+
+static inline
+unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
+{
+	struct mem_cgroup_per_zone *mz;
+
+	mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
+	return mz->lru_size[lru];
+}
+
+static inline int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
+{
+	unsigned long inactive_ratio;
+	unsigned long inactive;
+	unsigned long active;
+	unsigned long gb;
+
+	inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_ANON);
+	active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_ANON);
+
+	gb = (inactive + active) >> (30 - PAGE_SHIFT);
+	if (gb)
+		inactive_ratio = int_sqrt(10 * gb);
+	else
+		inactive_ratio = 1;
+
+	return inactive * inactive_ratio < active;
+}
+
 extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
 					struct task_struct *p);
 
@@ -156,18 +429,26 @@ bool mem_cgroup_oom_synchronize(bool wait);
 extern int do_swap_account;
 #endif
 
-static inline bool mem_cgroup_disabled(void)
-{
-	if (memory_cgrp_subsys.disabled)
-		return true;
-	return false;
-}
-
 struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page);
-void mem_cgroup_update_page_stat(struct mem_cgroup *memcg,
-				 enum mem_cgroup_stat_index idx, int val);
 void mem_cgroup_end_page_stat(struct mem_cgroup *memcg);
 
+/**
+ * mem_cgroup_update_page_stat - update page state statistics
+ * @memcg: memcg to account against
+ * @idx: page state item to account
+ * @val: number of pages (positive or negative)
+ *
+ * See mem_cgroup_begin_page_stat() for locking requirements.
+ */
+static inline void mem_cgroup_update_page_stat(struct mem_cgroup *memcg,
+				 enum mem_cgroup_stat_index idx, int val)
+{
+	VM_BUG_ON(!rcu_read_lock_held());
+
+	if (memcg)
+		this_cpu_add(memcg->stat->count[idx], val);
+}
+
 static inline void mem_cgroup_inc_page_stat(struct mem_cgroup *memcg,
 					    enum mem_cgroup_stat_index idx)
 {
@@ -184,13 +465,31 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
 						gfp_t gfp_mask,
 						unsigned long *total_scanned);
 
-void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);
 static inline void mem_cgroup_count_vm_event(struct mm_struct *mm,
 					     enum vm_event_item idx)
 {
+	struct mem_cgroup *memcg;
+
 	if (mem_cgroup_disabled())
 		return;
-	__mem_cgroup_count_vm_event(mm, idx);
+
+	rcu_read_lock();
+	memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
+	if (unlikely(!memcg))
+		goto out;
+
+	switch (idx) {
+	case PGFAULT:
+		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]);
+		break;
+	case PGMAJFAULT:
+		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
+		break;
+	default:
+		BUG();
+	}
+out:
+	rcu_read_unlock();
 }
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 void mem_cgroup_split_huge_fixup(struct page *head);
@@ -275,12 +574,6 @@ static inline bool task_in_mem_cgroup(struct task_struct *task,
 	return true;
 }
 
-static inline struct cgroup_subsys_state
-		*mem_cgroup_css(struct mem_cgroup *memcg)
-{
-	return NULL;
-}
-
 static inline struct mem_cgroup *
 mem_cgroup_iter(struct mem_cgroup *root,
 		struct mem_cgroup *prev,
@@ -444,7 +737,10 @@ static inline bool memcg_kmem_enabled(void)
 	return static_key_false(&memcg_kmem_enabled_key);
 }
 
-bool memcg_kmem_is_active(struct mem_cgroup *memcg);
+static inline bool memcg_kmem_is_active(struct mem_cgroup *memcg)
+{
+	return memcg->kmem_acct_active;
+}
 
 /*
  * In general, we'll do everything in our power to not incur in any overhead
@@ -463,7 +759,15 @@ void __memcg_kmem_commit_charge(struct page *page,
 				       struct mem_cgroup *memcg, int order);
 void __memcg_kmem_uncharge_pages(struct page *page, int order);
 
-int memcg_cache_id(struct mem_cgroup *memcg);
+/*
+ * helper for acessing a memcg's index. It will be used as an index in the
+ * child cache array in kmem_cache, and also to derive its name. This function
+ * will return -1 when this is not a kmem-limited memcg.
+ */
+static inline int memcg_cache_id(struct mem_cgroup *memcg)
+{
+	return memcg ? memcg->kmemcg_id : -1;
+}
 
 struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep);
 void __memcg_kmem_put_cache(struct kmem_cache *cachep);
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 6282f1eb3d6a..2ce190709280 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -351,7 +351,15 @@ extern void check_move_unevictable_pages(struct page **, int nr_pages);
 extern int kswapd_run(int nid);
 extern void kswapd_stop(int nid);
 #ifdef CONFIG_MEMCG
-extern int mem_cgroup_swappiness(struct mem_cgroup *mem);
+static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
+{
+	/* root ? */
+	if (mem_cgroup_disabled() || !memcg->css.parent)
+		return vm_swappiness;
+
+	return memcg->swappiness;
+}
+
 #else
 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
 {
diff --git a/include/net/sock.h b/include/net/sock.h
index 43c6abcf06ab..a98c71ea40c5 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1042,34 +1042,6 @@ struct proto {
 #endif
 };
 
-/*
- * Bits in struct cg_proto.flags
- */
-enum cg_proto_flags {
-	/* Currently active and new sockets should be assigned to cgroups */
-	MEMCG_SOCK_ACTIVE,
-	/* It was ever activated; we must disarm static keys on destruction */
-	MEMCG_SOCK_ACTIVATED,
-};
-
-struct cg_proto {
-	struct page_counter	memory_allocated;	/* Current allocated memory. */
-	struct percpu_counter	sockets_allocated;	/* Current number of sockets. */
-	int			memory_pressure;
-	long			sysctl_mem[3];
-	unsigned long		flags;
-	/*
-	 * memcg field is used to find which memcg we belong directly
-	 * Each memcg struct can hold more than one cg_proto, so container_of
-	 * won't really cut.
-	 *
-	 * The elegant solution would be having an inverse function to
-	 * proto_cgroup in struct proto, but that means polluting the structure
-	 * for everybody, instead of just for memcg users.
-	 */
-	struct mem_cgroup	*memcg;
-};
-
 int proto_register(struct proto *prot, int alloc_slab);
 void proto_unregister(struct proto *prot);