memcg: make __mod_memcg_lruvec_state re-entrant safe against irqs

Let's make __mod_memcg_lruvec_state re-entrant safe and name it
mod_memcg_lruvec_state().  The only thing needed is to convert the usage
of __this_cpu_add() to this_cpu_add().  There are two callers of
mod_memcg_lruvec_state() and one of them i.e.  __mod_objcg_mlstate() will
be re-entrant safe as well, so, rename it mod_objcg_mlstate().  The last
caller __mod_lruvec_state() still calls __mod_node_page_state() which is
not re-entrant safe yet, so keep it as is.

Link: https://lkml.kernel.org/r/20250514184158.3471331-6-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: shakeelb

mm/memcontrol.c

@@ -725,7 +725,7 @@ unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)
 }
 #endif
 
-static void __mod_memcg_lruvec_state(struct lruvec *lruvec,
+static void mod_memcg_lruvec_state(struct lruvec *lruvec,
 				     enum node_stat_item idx,
 				     int val)
 {
@@ -743,10 +743,10 @@ static void __mod_memcg_lruvec_state(struct lruvec *lruvec,
 	cpu = get_cpu();
 
 	/* Update memcg */
-	__this_cpu_add(memcg->vmstats_percpu->state[i], val);
+	this_cpu_add(memcg->vmstats_percpu->state[i], val);
 
 	/* Update lruvec */
-	__this_cpu_add(pn->lruvec_stats_percpu->state[i], val);
+	this_cpu_add(pn->lruvec_stats_percpu->state[i], val);
 
 	val = memcg_state_val_in_pages(idx, val);
 	memcg_rstat_updated(memcg, val, cpu);
@@ -773,7 +773,7 @@ void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
 
 	/* Update memcg and lruvec */
 	if (!mem_cgroup_disabled())
-		__mod_memcg_lruvec_state(lruvec, idx, val);
+		mod_memcg_lruvec_state(lruvec, idx, val);
 }
 
 void __lruvec_stat_mod_folio(struct folio *folio, enum node_stat_item idx,
@@ -2525,7 +2525,7 @@ static void commit_charge(struct folio *folio, struct mem_cgroup *memcg)
 	folio->memcg_data = (unsigned long)memcg;
 }
 
-static inline void __mod_objcg_mlstate(struct obj_cgroup *objcg,
+static inline void mod_objcg_mlstate(struct obj_cgroup *objcg,
 				       struct pglist_data *pgdat,
 				       enum node_stat_item idx, int nr)
 {
@@ -2535,7 +2535,7 @@ static inline void __mod_objcg_mlstate(struct obj_cgroup *objcg,
 	rcu_read_lock();
 	memcg = obj_cgroup_memcg(objcg);
 	lruvec = mem_cgroup_lruvec(memcg, pgdat);
-	__mod_memcg_lruvec_state(lruvec, idx, nr);
+	mod_memcg_lruvec_state(lruvec, idx, nr);
 	rcu_read_unlock();
 }
 
@@ -2845,12 +2845,12 @@ static void __account_obj_stock(struct obj_cgroup *objcg,
 		struct pglist_data *oldpg = stock->cached_pgdat;
 
 		if (stock->nr_slab_reclaimable_b) {
-			__mod_objcg_mlstate(objcg, oldpg, NR_SLAB_RECLAIMABLE_B,
+			mod_objcg_mlstate(objcg, oldpg, NR_SLAB_RECLAIMABLE_B,
 					  stock->nr_slab_reclaimable_b);
 			stock->nr_slab_reclaimable_b = 0;
 		}
 		if (stock->nr_slab_unreclaimable_b) {
-			__mod_objcg_mlstate(objcg, oldpg, NR_SLAB_UNRECLAIMABLE_B,
+			mod_objcg_mlstate(objcg, oldpg, NR_SLAB_UNRECLAIMABLE_B,
 					  stock->nr_slab_unreclaimable_b);
 			stock->nr_slab_unreclaimable_b = 0;
 		}
@@ -2876,7 +2876,7 @@ static void __account_obj_stock(struct obj_cgroup *objcg,
 		}
 	}
 	if (nr)
-		__mod_objcg_mlstate(objcg, pgdat, idx, nr);
+		mod_objcg_mlstate(objcg, pgdat, idx, nr);
 }
 
 static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
@@ -2945,13 +2945,13 @@ static void drain_obj_stock(struct obj_stock_pcp *stock)
 	 */
 	if (stock->nr_slab_reclaimable_b || stock->nr_slab_unreclaimable_b) {
 		if (stock->nr_slab_reclaimable_b) {
-			__mod_objcg_mlstate(old, stock->cached_pgdat,
+			mod_objcg_mlstate(old, stock->cached_pgdat,
 					  NR_SLAB_RECLAIMABLE_B,
 					  stock->nr_slab_reclaimable_b);
 			stock->nr_slab_reclaimable_b = 0;
 		}
 		if (stock->nr_slab_unreclaimable_b) {
-			__mod_objcg_mlstate(old, stock->cached_pgdat,
+			mod_objcg_mlstate(old, stock->cached_pgdat,
 					  NR_SLAB_UNRECLAIMABLE_B,
 					  stock->nr_slab_unreclaimable_b);
 			stock->nr_slab_unreclaimable_b = 0;