+ mm-memcontrol-consolidate-lruvec-stat-flushing.patch added to -mm tree

+ mm-memcontrol-consolidate-lruvec-stat-flushing.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm: memcontrol: consolidate lruvec stat flushing
has been added to the -mm tree.  Its filename is
     mm-memcontrol-consolidate-lruvec-stat-flushing.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-memcontrol-consolidate-lruvec-stat-flushing.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-memcontrol-consolidate-lruvec-stat-flushing.patch

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------------------------------------------------------
From: Johannes Weiner <hannes@cmpxchg.org>
Subject: mm: memcontrol: consolidate lruvec stat flushing

There are two functions to flush the per-cpu data of an lruvec into the
rest of the cgroup tree: when the cgroup is being freed, and when a CPU
disappears during hotplug.  The difference is whether all CPUs or just one
is being collected, but the rest of the flushing code is the same.  Merge
them into one function and share the common code.

Link: https://lkml.kernel.org/r/20210209163304.77088-8-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memcontrol.c |   76 +++++++++++++++++-----------------------------
 1 file changed, 29 insertions(+), 47 deletions(-)

--- a/mm/memcontrol.c~mm-memcontrol-consolidate-lruvec-stat-flushing
+++ a/mm/memcontrol.c
@@ -2369,6 +2369,29 @@ static void drain_all_stock(struct mem_c
 	mutex_unlock(&percpu_charge_mutex);
 }
 
+static void memcg_flush_lruvec_page_state(struct mem_cgroup *memcg, int cpu)
+{
+	int nid;
+
+	for_each_node(nid) {
+		struct mem_cgroup_per_node *pn = memcg->nodeinfo[nid];
+		unsigned long stat[NR_VM_NODE_STAT_ITEMS];
+		struct batched_lruvec_stat *lstatc;
+		int i;
+
+		lstatc = per_cpu_ptr(pn->lruvec_stat_cpu, cpu);
+		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
+			stat[i] = lstatc->count[i];
+			lstatc->count[i] = 0;
+		}
+
+		do {
+			for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
+				atomic_long_add(stat[i], &pn->lruvec_stat[i]);
+		} while ((pn = parent_nodeinfo(pn, nid)));
+	}
+}
+
 static int memcg_hotplug_cpu_dead(unsigned int cpu)
 {
 	struct memcg_stock_pcp *stock;
@@ -2377,31 +2400,8 @@ static int memcg_hotplug_cpu_dead(unsign
 	stock = &per_cpu(memcg_stock, cpu);
 	drain_stock(stock);
 
-	for_each_mem_cgroup(memcg) {
-		int i;
-
-		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
-			int nid;
-
-			for_each_node(nid) {
-				struct batched_lruvec_stat *lstatc;
-				struct mem_cgroup_per_node *pn;
-				long x;
-
-				pn = memcg->nodeinfo[nid];
-				lstatc = per_cpu_ptr(pn->lruvec_stat_cpu, cpu);
-
-				x = lstatc->count[i];
-				lstatc->count[i] = 0;
-
-				if (x) {
-					do {
-						atomic_long_add(x, &pn->lruvec_stat[i]);
-					} while ((pn = parent_nodeinfo(pn, nid)));
-				}
-			}
-		}
-	}
+	for_each_mem_cgroup(memcg)
+		memcg_flush_lruvec_page_state(memcg, cpu);
 
 	return 0;
 }
@@ -3588,27 +3588,6 @@ static u64 mem_cgroup_read_u64(struct cg
 	}
 }
 
-static void memcg_flush_lruvec_page_state(struct mem_cgroup *memcg)
-{
-	int node;
-
-	for_each_node(node) {
-		struct mem_cgroup_per_node *pn = memcg->nodeinfo[node];
-		unsigned long stat[NR_VM_NODE_STAT_ITEMS] = { 0 };
-		struct mem_cgroup_per_node *pi;
-		int cpu, i;
-
-		for_each_online_cpu(cpu)
-			for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
-				stat[i] += per_cpu(
-					pn->lruvec_stat_cpu->count[i], cpu);
-
-		for (pi = pn; pi; pi = parent_nodeinfo(pi, node))
-			for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
-				atomic_long_add(stat[i], &pi->lruvec_stat[i]);
-	}
-}
-
 #ifdef CONFIG_MEMCG_KMEM
 static int memcg_online_kmem(struct mem_cgroup *memcg)
 {
@@ -5144,12 +5123,15 @@ static void __mem_cgroup_free(struct mem
 
 static void mem_cgroup_free(struct mem_cgroup *memcg)
 {
+	int cpu;
+
 	memcg_wb_domain_exit(memcg);
 	/*
 	 * Flush percpu lruvec stats to guarantee the value
 	 * correctness on parent's and all ancestor levels.
 	 */
-	memcg_flush_lruvec_page_state(memcg);
+	for_each_online_cpu(cpu)
+		memcg_flush_lruvec_page_state(memcg, cpu);
 	__mem_cgroup_free(memcg);
 }
 
_

Patches currently in -mm which might be from hannes@cmpxchg.org are

mm-page-writeback-simplify-memcg-handling-in-test_clear_page_writeback.patch
mm-memcontrol-fix-cpuhotplug-statistics-flushing.patch
mm-memcontrol-kill-mem_cgroup_nodeinfo.patch
mm-memcontrol-privatize-memcg_page_state-query-functions.patch
cgroup-rstat-support-cgroup1.patch
cgroup-rstat-punt-root-level-optimization-to-individual-controllers.patch
mm-memcontrol-switch-to-rstat.patch
mm-memcontrol-consolidate-lruvec-stat-flushing.patch
kselftests-cgroup-update-kmem-test-for-new-vmstat-implementation.patch