mm: memcg: move memcg_account_kmem() to memcontrol-v1.c

Patch series "mm: memcg: put cgroup v1-specific memcg data under
CONFIG_MEMCG_V1".

This patchset puts all cgroup v1's members of struct mem_cgroup, struct
mem_cgroup_per_node and struct task_struct under the CONFIG_MEMCG_V1
config option.  If cgroup v1 support is not required (and it's true for
many cgroup users these days), it allows to save a bit of memory and
compile out some code, some of which is on relatively hot paths.  It also
structures the code a bit better by grouping cgroup v1-specific stuff in
one place.


This patch (of 9):

memcg_account_kmem() consists of a trivial statistics change via
mod_memcg_state() call and a relatively large memcg1-specific part.

Let's factor out the mod_memcg_state() call and move the rest into the
mm/memcontrol-v1.c file.  Also rename memcg_account_kmem() into
memcg1_account_kmem() for consistency.

Link: https://lkml.kernel.org/r/20240628210317.272856-1-roman.gushchin@linux.dev
Link: https://lkml.kernel.org/r/20240628210317.272856-2-roman.gushchin@linux.devSigned-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memcontrol-v1.c

@@ -2913,6 +2913,18 @@ struct cftype memsw_files[] = {
 	{ },	/* terminate */
 };
 
+#ifdef CONFIG_MEMCG_KMEM
+void memcg1_account_kmem(struct mem_cgroup *memcg, int nr_pages)
+{
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
+		if (nr_pages > 0)
+			page_counter_charge(&memcg->kmem, nr_pages);
+		else
+			page_counter_uncharge(&memcg->kmem, -nr_pages);
+	}
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
 static int __init memcg1_init(void)
 {
 	int node;

mm/memcontrol-v1.h

@@ -102,6 +102,7 @@ void memcg1_check_events(struct mem_cgroup *memcg, int nid);
 
 void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s);
 
+void memcg1_account_kmem(struct mem_cgroup *memcg, int nr_pages);
 extern struct cftype memsw_files[];
 extern struct cftype mem_cgroup_legacy_files[];
 
@@ -120,6 +121,7 @@ static inline void memcg1_check_events(struct mem_cgroup *memcg, int nid) {}
 
 static inline void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s) {}
 
+static inline void memcg1_account_kmem(struct mem_cgroup *memcg, int nr_pages) {}
 extern struct cftype memsw_files[];
 extern struct cftype mem_cgroup_legacy_files[];
 #endif	/* CONFIG_MEMCG_V1 */

mm/memcontrol.c

@@ -1721,7 +1721,6 @@ static DEFINE_MUTEX(percpu_charge_mutex);
 static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock);
 static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
 				     struct mem_cgroup *root_memcg);
-static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages);
 
 #else
 static inline struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock)
@@ -1733,9 +1732,6 @@ static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
 {
 	return false;
 }
-static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages)
-{
-}
 #endif
 
 /**
@@ -2645,18 +2641,6 @@ struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio)
 	return objcg;
 }
 
-static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages)
-{
-	mod_memcg_state(memcg, MEMCG_KMEM, nr_pages);
-	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
-		if (nr_pages > 0)
-			page_counter_charge(&memcg->kmem, nr_pages);
-		else
-			page_counter_uncharge(&memcg->kmem, -nr_pages);
-	}
-}
-
-
 /*
  * obj_cgroup_uncharge_pages: uncharge a number of kernel pages from a objcg
  * @objcg: object cgroup to uncharge
@@ -2669,7 +2653,8 @@ static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
 
 	memcg = get_mem_cgroup_from_objcg(objcg);
 
-	memcg_account_kmem(memcg, -nr_pages);
+	mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages);
+	memcg1_account_kmem(memcg, -nr_pages);
 	refill_stock(memcg, nr_pages);
 
 	css_put(&memcg->css);
@@ -2695,7 +2680,8 @@ static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp,
 	if (ret)
 		goto out;
 
-	memcg_account_kmem(memcg, nr_pages);
+	mod_memcg_state(memcg, MEMCG_KMEM, nr_pages);
+	memcg1_account_kmem(memcg, nr_pages);
 out:
 	css_put(&memcg->css);
 
@@ -2848,7 +2834,8 @@ static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock)
 
 			memcg = get_mem_cgroup_from_objcg(old);
 
-			memcg_account_kmem(memcg, -nr_pages);
+			mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages);
+			memcg1_account_kmem(memcg, -nr_pages);
 			__refill_stock(memcg, nr_pages);
 
 			css_put(&memcg->css);
@@ -4771,8 +4758,10 @@ static void uncharge_batch(const struct uncharge_gather *ug)
 		page_counter_uncharge(&ug->memcg->memory, ug->nr_memory);
 		if (do_memsw_account())
 			page_counter_uncharge(&ug->memcg->memsw, ug->nr_memory);
-		if (ug->nr_kmem)
-			memcg_account_kmem(ug->memcg, -ug->nr_kmem);
+		if (ug->nr_kmem) {
+			mod_memcg_state(ug->memcg, MEMCG_KMEM, -ug->nr_kmem);
+			memcg1_account_kmem(ug->memcg, -ug->nr_kmem);
+		}
 		memcg1_oom_recover(ug->memcg);
 	}