mm: memcg: guard memcg1-specific fields accesses in mm/memcontrol.c

There are only few memcg1-specific struct mem_cgroup's members accesses
left in mm/memcontrol.c.  Let's guard them with the CONFIG_MEMCG_V1 config
option.

Link: https://lkml.kernel.org/r/20240628210317.272856-6-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.c

@@ -3637,20 +3637,23 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 	page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX);
 	if (parent) {
 		WRITE_ONCE(memcg->swappiness, mem_cgroup_swappiness(parent));
-		WRITE_ONCE(memcg->oom_kill_disable, READ_ONCE(parent->oom_kill_disable));
 
 		page_counter_init(&memcg->memory, &parent->memory);
 		page_counter_init(&memcg->swap, &parent->swap);
+#ifdef CONFIG_MEMCG_V1
+		WRITE_ONCE(memcg->oom_kill_disable, READ_ONCE(parent->oom_kill_disable));
 		page_counter_init(&memcg->kmem, &parent->kmem);
 		page_counter_init(&memcg->tcpmem, &parent->tcpmem);
+#endif
 	} else {
 		init_memcg_stats();
 		init_memcg_events();
 		page_counter_init(&memcg->memory, NULL);
 		page_counter_init(&memcg->swap, NULL);
+#ifdef CONFIG_MEMCG_V1
 		page_counter_init(&memcg->kmem, NULL);
 		page_counter_init(&memcg->tcpmem, NULL);
-
+#endif
 		root_mem_cgroup = memcg;
 		return &memcg->css;
 	}
@@ -3785,8 +3788,10 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
 
 	page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX);
 	page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX);
+#ifdef CONFIG_MEMCG_V1
 	page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX);
 	page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX);
+#endif
 	page_counter_set_min(&memcg->memory, 0);
 	page_counter_set_low(&memcg->memory, 0);
 	page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX);