mm: memcontrol: introduce CONFIG_MEMCG_LEGACY_KMEM

Let the user know that CONFIG_MEMCG_KMEM does not apply to the cgroup2
interface. This also makes legacy-only code sections stand out better.

[arnd@arndb.de: mm: memcontrol: only manage socket pressure for CONFIG_INET]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 11 insertions, 9 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2239e6dd4d4c..92e8ab67b6df 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3001,7 +3001,7 @@ static void memcg_free_kmem(struct mem_cgroup *memcg)
 }
 #endif /* !CONFIG_SLOB */
 
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG_LEGACY_KMEM
 static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
                                    unsigned long limit)
 {
@@ -3025,7 +3025,7 @@ static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
 {
         return -EINVAL;
 }
-#endif /* CONFIG_MEMCG_KMEM */
+#endif /* CONFIG_MEMCG_LEGACY_KMEM */
 
 
 /*
@@ -4039,7 +4039,7 @@ static struct cftype mem_cgroup_legacy_files[] = {
                 .seq_show = memcg_numa_stat_show,
         },
 #endif
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG_LEGACY_KMEM
         {
                 .name = "kmem.limit_in_bytes",
                 .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
@@ -4266,13 +4266,13 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
         if (ret)
                 return ret;
 
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_INET
+#ifdef CONFIG_MEMCG_LEGACY_KMEM
         ret = tcp_init_cgroup(memcg);
         if (ret)
                 return ret;
 #endif
 
-#ifdef CONFIG_INET
         if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
                 static_branch_inc(&memcg_sockets_enabled_key);
 #endif
@@ -4329,7 +4329,7 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
 
         memcg_free_kmem(memcg);
 
-#ifdef CONFIG_MEMCG_KMEM
+#if defined(CONFIG_MEMCG_LEGACY_KMEM) && defined(CONFIG_INET)
         tcp_destroy_cgroup(memcg);
 #endif
 
@@ -5558,7 +5558,7 @@ void sock_update_memcg(struct sock *sk)
         memcg = mem_cgroup_from_task(current);
         if (memcg == root_mem_cgroup)
                 goto out;
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG_LEGACY_KMEM
         if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !memcg->tcp_mem.active)
                 goto out;
 #endif
@@ -5587,7 +5587,7 @@ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
 {
         gfp_t gfp_mask = GFP_KERNEL;
 
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG_LEGACY_KMEM
         if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
                 struct page_counter *counter;
 
@@ -5619,7 +5619,7 @@ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
  */
 void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
 {
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG_LEGACY_KMEM
         if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
                 page_counter_uncharge(&memcg->tcp_mem.memory_allocated,
                                       nr_pages);
diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index 9a6c0704211c..89b1d441af4b 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -275,6 +275,7 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
 
                 level = vmpressure_calc_level(scanned, reclaimed);
 
+#ifdef CONFIG_INET
                 if (level > VMPRESSURE_LOW) {
                         /*
                          * Let the socket buffer allocator know that
@@ -286,6 +287,7 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
                          */
                         memcg->socket_pressure = jiffies + HZ;
                 }
+#endif
         }
 }