mm, memcg: rename ambiguously named memory.stat counters and functions

I spent literally an hour trying to work out why an earlier version of
my memory.events aggregation code doesn't work properly, only to find
out I was calling memcg->events instead of memcg->memory_events, which
is fairly confusing.

This naming seems in need of reworking, so make it harder to do the
wrong thing by using vmevents instead of events, which makes it more
clear that these are vm counters rather than memcg-specific counters.

There are also a few other inconsistent names in both the percpu and
aggregated structs, so these are all cleaned up to be more coherent and
easy to understand.

This commit contains code cleanup only: there are no logic changes.

[[e-mail]: fix it for preceding changes]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Chris Down <[e-mail]>
Acked-by: Johannes Weiner <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Tejun Heo <[e-mail]>
Cc: Roman Gushchin <[e-mail]>
Cc: Dennis Zhou <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/memcontrol.h

···
 	MEM_CGROUP_NTARGETS,
 };
 
-struct mem_cgroup_stat_cpu {
-	long count[MEMCG_NR_STAT];
+struct memcg_vmstats_percpu {
+	long stat[MEMCG_NR_STAT];
 	unsigned long events[NR_VM_EVENT_ITEMS];
 	unsigned long nr_page_events;
 	unsigned long targets[MEM_CGROUP_NTARGETS];
···
 	struct task_struct	*move_lock_task;
 
 	/* memory.stat */
-	struct mem_cgroup_stat_cpu __percpu *stat_cpu;
+	struct memcg_vmstats_percpu __percpu *vmstats_percpu;
 
 	MEMCG_PADDING(_pad2_);
 
-	atomic_long_t		stat[MEMCG_NR_STAT];
-	atomic_long_t		events[NR_VM_EVENT_ITEMS];
+	atomic_long_t		vmstats[MEMCG_NR_STAT];
+	atomic_long_t		vmevents[NR_VM_EVENT_ITEMS];
 	atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
 
 	unsigned long		socket_pressure;
···
 static inline unsigned long memcg_page_state(struct mem_cgroup *memcg,
 					     int idx)
 {
-	long x = atomic_long_read(&memcg->stat[idx]);
+	long x = atomic_long_read(&memcg->vmstats[idx]);
 #ifdef CONFIG_SMP
 	if (x < 0)
 		x = 0;
···
 	if (mem_cgroup_disabled())
 		return;
 
-	x = val + __this_cpu_read(memcg->stat_cpu->count[idx]);
+	x = val + __this_cpu_read(memcg->vmstats_percpu->stat[idx]);
 	if (unlikely(abs(x) > MEMCG_CHARGE_BATCH)) {
-		atomic_long_add(x, &memcg->stat[idx]);
+		atomic_long_add(x, &memcg->vmstats[idx]);
 		x = 0;
 	}
-	__this_cpu_write(memcg->stat_cpu->count[idx], x);
+	__this_cpu_write(memcg->vmstats_percpu->stat[idx], x);
 }
 
 /* idx can be of type enum memcg_stat_item or node_stat_item */
···
 	if (mem_cgroup_disabled())
 		return;
 
-	x = count + __this_cpu_read(memcg->stat_cpu->events[idx]);
+	x = count + __this_cpu_read(memcg->vmstats_percpu->events[idx]);
 	if (unlikely(x > MEMCG_CHARGE_BATCH)) {
-		atomic_long_add(x, &memcg->events[idx]);
+		atomic_long_add(x, &memcg->vmevents[idx]);
 		x = 0;
 	}
-	__this_cpu_write(memcg->stat_cpu->events[idx], x);
+	__this_cpu_write(memcg->vmstats_percpu->events[idx], x);
 }
 
 static inline void count_memcg_events(struct mem_cgroup *memcg,

mm/memcontrol.c

···
 static unsigned long memcg_sum_events(struct mem_cgroup *memcg,
 				      int event)
 {
-	return atomic_long_read(&memcg->events[event]);
+	return atomic_long_read(&memcg->vmevents[event]);
 }
 
 static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
···
 		nr_pages = -nr_pages; /* for event */
 	}
 
-	__this_cpu_add(memcg->stat_cpu->nr_page_events, nr_pages);
+	__this_cpu_add(memcg->vmstats_percpu->nr_page_events, nr_pages);
 }
 
 static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
···
 {
 	unsigned long val, next;
 
-	val = __this_cpu_read(memcg->stat_cpu->nr_page_events);
-	next = __this_cpu_read(memcg->stat_cpu->targets[target]);
+	val = __this_cpu_read(memcg->vmstats_percpu->nr_page_events);
+	next = __this_cpu_read(memcg->vmstats_percpu->targets[target]);
 	/* from time_after() in jiffies.h */
 	if ((long)(next - val) < 0) {
 		switch (target) {
···
 		default:
 			break;
 		}
-		__this_cpu_write(memcg->stat_cpu->targets[target], next);
+		__this_cpu_write(memcg->vmstats_percpu->targets[target], next);
 		return true;
 	}
 	return false;
···
 			int nid;
 			long x;
 
-			x = this_cpu_xchg(memcg->stat_cpu->count[i], 0);
+			x = this_cpu_xchg(memcg->vmstats_percpu->stat[i], 0);
 			if (x)
-				atomic_long_add(x, &memcg->stat[i]);
+				atomic_long_add(x, &memcg->vmstats[i]);
 
 			if (i >= NR_VM_NODE_STAT_ITEMS)
 				continue;
···
 		for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
 			long x;
 
-			x = this_cpu_xchg(memcg->stat_cpu->events[i], 0);
+			x = this_cpu_xchg(memcg->vmstats_percpu->events[i], 0);
 			if (x)
-				atomic_long_add(x, &memcg->events[i]);
+				atomic_long_add(x, &memcg->vmevents[i]);
 		}
 	}
 
···
 	return retval;
 }
 
-struct accumulated_stats {
-	unsigned long stat[MEMCG_NR_STAT];
-	unsigned long events[NR_VM_EVENT_ITEMS];
+struct accumulated_vmstats {
+	unsigned long vmstats[MEMCG_NR_STAT];
+	unsigned long vmevents[NR_VM_EVENT_ITEMS];
 	unsigned long lru_pages[NR_LRU_LISTS];
-	const unsigned int *stats_array;
-	const unsigned int *events_array;
-	int stats_size;
-	int events_size;
+
+	/* overrides for v1 */
+	const unsigned int *vmstats_array;
+	const unsigned int *vmevents_array;
+
+	int vmstats_size;
+	int vmevents_size;
 };
 
-static void accumulate_memcg_tree(struct mem_cgroup *memcg,
-				  struct accumulated_stats *acc)
+static void accumulate_vmstats(struct mem_cgroup *memcg,
+			       struct accumulated_vmstats *acc)
 {
 	struct mem_cgroup *mi;
 	int i;
 
 	for_each_mem_cgroup_tree(mi, memcg) {
-		for (i = 0; i < acc->stats_size; i++)
-			acc->stat[i] += memcg_page_state(mi,
-				acc->stats_array ? acc->stats_array[i] : i);
+		for (i = 0; i < acc->vmstats_size; i++)
+			acc->vmstats[i] += memcg_page_state(mi,
+				acc->vmstats_array ? acc->vmstats_array[i] : i);
 
-		for (i = 0; i < acc->events_size; i++)
-			acc->events[i] += memcg_sum_events(mi,
-				acc->events_array ? acc->events_array[i] : i);
+		for (i = 0; i < acc->vmevents_size; i++)
+			acc->vmevents[i] += memcg_sum_events(mi,
+				acc->vmevents_array
+				? acc->vmevents_array[i] : i);
 
 		for (i = 0; i < NR_LRU_LISTS; i++)
 			acc->lru_pages[i] += memcg_page_state(mi,
···
 	unsigned long memory, memsw;
 	struct mem_cgroup *mi;
 	unsigned int i;
-	struct accumulated_stats acc;
+	struct accumulated_vmstats acc;
 
 	BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats));
 	BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS);
···
 			   (u64)memsw * PAGE_SIZE);
 
 	memset(&acc, 0, sizeof(acc));
-	acc.stats_size = ARRAY_SIZE(memcg1_stats);
-	acc.stats_array = memcg1_stats;
-	acc.events_size = ARRAY_SIZE(memcg1_events);
-	acc.events_array = memcg1_events;
-	accumulate_memcg_tree(memcg, &acc);
+	acc.vmstats_size = ARRAY_SIZE(memcg1_stats);
+	acc.vmstats_array = memcg1_stats;
+	acc.vmevents_size = ARRAY_SIZE(memcg1_events);
+	acc.vmevents_array = memcg1_events;
+	accumulate_vmstats(memcg, &acc);
 
 	for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
 		if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
 			continue;
 		seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i],
-			   (u64)acc.stat[i] * PAGE_SIZE);
+			   (u64)acc.vmstats[i] * PAGE_SIZE);
 	}
 
 	for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
 		seq_printf(m, "total_%s %llu\n", memcg1_event_names[i],
-			   (u64)acc.events[i]);
+			   (u64)acc.vmevents[i]);
 
 	for (i = 0; i < NR_LRU_LISTS; i++)
 		seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i],
···
  */
 static unsigned long memcg_exact_page_state(struct mem_cgroup *memcg, int idx)
 {
-	long x = atomic_long_read(&memcg->stat[idx]);
+	long x = atomic_long_read(&memcg->vmstats[idx]);
 	int cpu;
 
 	for_each_online_cpu(cpu)
-		x += per_cpu_ptr(memcg->stat_cpu, cpu)->count[idx];
+		x += per_cpu_ptr(memcg->vmstats_percpu, cpu)->stat[idx];
 	if (x < 0)
 		x = 0;
 	return x;
···
 
 	for_each_node(node)
 		free_mem_cgroup_per_node_info(memcg, node);
-	free_percpu(memcg->stat_cpu);
+	free_percpu(memcg->vmstats_percpu);
 	kfree(memcg);
 }
 
···
 	if (memcg->id.id < 0)
 		goto fail;
 
-	memcg->stat_cpu = alloc_percpu(struct mem_cgroup_stat_cpu);
-	if (!memcg->stat_cpu)
+	memcg->vmstats_percpu = alloc_percpu(struct memcg_vmstats_percpu);
+	if (!memcg->vmstats_percpu)
 		goto fail;
 
 	for_each_node(node)
···
 static int memory_stat_show(struct seq_file *m, void *v)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
-	struct accumulated_stats acc;
+	struct accumulated_vmstats acc;
 	int i;
 
 	/*
···
 	 */
 
 	memset(&acc, 0, sizeof(acc));
-	acc.stats_size = MEMCG_NR_STAT;
-	acc.events_size = NR_VM_EVENT_ITEMS;
-	accumulate_memcg_tree(memcg, &acc);
+	acc.vmstats_size = MEMCG_NR_STAT;
+	acc.vmevents_size = NR_VM_EVENT_ITEMS;
+	accumulate_vmstats(memcg, &acc);
 
 	seq_printf(m, "anon %llu\n",
-		   (u64)acc.stat[MEMCG_RSS] * PAGE_SIZE);
+		   (u64)acc.vmstats[MEMCG_RSS] * PAGE_SIZE);
 	seq_printf(m, "file %llu\n",
-		   (u64)acc.stat[MEMCG_CACHE] * PAGE_SIZE);
+		   (u64)acc.vmstats[MEMCG_CACHE] * PAGE_SIZE);
 	seq_printf(m, "kernel_stack %llu\n",
-		   (u64)acc.stat[MEMCG_KERNEL_STACK_KB] * 1024);
+		   (u64)acc.vmstats[MEMCG_KERNEL_STACK_KB] * 1024);
 	seq_printf(m, "slab %llu\n",
-		   (u64)(acc.stat[NR_SLAB_RECLAIMABLE] +
-			 acc.stat[NR_SLAB_UNRECLAIMABLE]) * PAGE_SIZE);
+		   (u64)(acc.vmstats[NR_SLAB_RECLAIMABLE] +
+			 acc.vmstats[NR_SLAB_UNRECLAIMABLE]) * PAGE_SIZE);
 	seq_printf(m, "sock %llu\n",
-		   (u64)acc.stat[MEMCG_SOCK] * PAGE_SIZE);
+		   (u64)acc.vmstats[MEMCG_SOCK] * PAGE_SIZE);
 
 	seq_printf(m, "shmem %llu\n",
-		   (u64)acc.stat[NR_SHMEM] * PAGE_SIZE);
+		   (u64)acc.vmstats[NR_SHMEM] * PAGE_SIZE);
 	seq_printf(m, "file_mapped %llu\n",
-		   (u64)acc.stat[NR_FILE_MAPPED] * PAGE_SIZE);
+		   (u64)acc.vmstats[NR_FILE_MAPPED] * PAGE_SIZE);
 	seq_printf(m, "file_dirty %llu\n",
-		   (u64)acc.stat[NR_FILE_DIRTY] * PAGE_SIZE);
+		   (u64)acc.vmstats[NR_FILE_DIRTY] * PAGE_SIZE);
 	seq_printf(m, "file_writeback %llu\n",
-		   (u64)acc.stat[NR_WRITEBACK] * PAGE_SIZE);
+		   (u64)acc.vmstats[NR_WRITEBACK] * PAGE_SIZE);
 
 	/*
 	 * TODO: We should eventually replace our own MEMCG_RSS_HUGE counter
···
 	 * where the page->mem_cgroup is set up and stable.
 	 */
 	seq_printf(m, "anon_thp %llu\n",
-		   (u64)acc.stat[MEMCG_RSS_HUGE] * PAGE_SIZE);
+		   (u64)acc.vmstats[MEMCG_RSS_HUGE] * PAGE_SIZE);
 
 	for (i = 0; i < NR_LRU_LISTS; i++)
 		seq_printf(m, "%s %llu\n", mem_cgroup_lru_names[i],
 			   (u64)acc.lru_pages[i] * PAGE_SIZE);
 
 	seq_printf(m, "slab_reclaimable %llu\n",
-		   (u64)acc.stat[NR_SLAB_RECLAIMABLE] * PAGE_SIZE);
+		   (u64)acc.vmstats[NR_SLAB_RECLAIMABLE] * PAGE_SIZE);
 	seq_printf(m, "slab_unreclaimable %llu\n",
-		   (u64)acc.stat[NR_SLAB_UNRECLAIMABLE] * PAGE_SIZE);
+		   (u64)acc.vmstats[NR_SLAB_UNRECLAIMABLE] * PAGE_SIZE);
 
 	/* Accumulated memory events */
 
-	seq_printf(m, "pgfault %lu\n", acc.events[PGFAULT]);
-	seq_printf(m, "pgmajfault %lu\n", acc.events[PGMAJFAULT]);
+	seq_printf(m, "pgfault %lu\n", acc.vmevents[PGFAULT]);
+	seq_printf(m, "pgmajfault %lu\n", acc.vmevents[PGMAJFAULT]);
 
 	seq_printf(m, "workingset_refault %lu\n",
-		   acc.stat[WORKINGSET_REFAULT]);
+		   acc.vmstats[WORKINGSET_REFAULT]);
 	seq_printf(m, "workingset_activate %lu\n",
-		   acc.stat[WORKINGSET_ACTIVATE]);
+		   acc.vmstats[WORKINGSET_ACTIVATE]);
 	seq_printf(m, "workingset_nodereclaim %lu\n",
-		   acc.stat[WORKINGSET_NODERECLAIM]);
+		   acc.vmstats[WORKINGSET_NODERECLAIM]);
 
-	seq_printf(m, "pgrefill %lu\n", acc.events[PGREFILL]);
-	seq_printf(m, "pgscan %lu\n", acc.events[PGSCAN_KSWAPD] +
-		   acc.events[PGSCAN_DIRECT]);
-	seq_printf(m, "pgsteal %lu\n", acc.events[PGSTEAL_KSWAPD] +
-		   acc.events[PGSTEAL_DIRECT]);
-	seq_printf(m, "pgactivate %lu\n", acc.events[PGACTIVATE]);
-	seq_printf(m, "pgdeactivate %lu\n", acc.events[PGDEACTIVATE]);
-	seq_printf(m, "pglazyfree %lu\n", acc.events[PGLAZYFREE]);
-	seq_printf(m, "pglazyfreed %lu\n", acc.events[PGLAZYFREED]);
+	seq_printf(m, "pgrefill %lu\n", acc.vmevents[PGREFILL]);
+	seq_printf(m, "pgscan %lu\n", acc.vmevents[PGSCAN_KSWAPD] +
+		   acc.vmevents[PGSCAN_DIRECT]);
+	seq_printf(m, "pgsteal %lu\n", acc.vmevents[PGSTEAL_KSWAPD] +
+		   acc.vmevents[PGSTEAL_DIRECT]);
+	seq_printf(m, "pgactivate %lu\n", acc.vmevents[PGACTIVATE]);
+	seq_printf(m, "pgdeactivate %lu\n", acc.vmevents[PGDEACTIVATE]);
+	seq_printf(m, "pglazyfree %lu\n", acc.vmevents[PGLAZYFREE]);
+	seq_printf(m, "pglazyfreed %lu\n", acc.vmevents[PGLAZYFREED]);
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-	seq_printf(m, "thp_fault_alloc %lu\n", acc.events[THP_FAULT_ALLOC]);
+	seq_printf(m, "thp_fault_alloc %lu\n", acc.vmevents[THP_FAULT_ALLOC]);
 	seq_printf(m, "thp_collapse_alloc %lu\n",
-		   acc.events[THP_COLLAPSE_ALLOC]);
+		   acc.vmevents[THP_COLLAPSE_ALLOC]);
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 	return 0;
···
 	__mod_memcg_state(ug->memcg, MEMCG_RSS_HUGE, -ug->nr_huge);
 	__mod_memcg_state(ug->memcg, NR_SHMEM, -ug->nr_shmem);
 	__count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
-	__this_cpu_add(ug->memcg->stat_cpu->nr_page_events, nr_pages);
+	__this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, nr_pages);
 	memcg_check_events(ug->memcg, ug->dummy_page);
 	local_irq_restore(flags);