mm: memcontrol: allow to disable kmem accounting for cgroup2

Kmem accounting might incur overhead that some users can't put up with.
Besides, the implementation is still considered unstable.  So let's
provide a way to disable it for those users who aren't happy with it.

To disable kmem accounting for cgroup2, pass cgroup.memory=nokmem at
boot time.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9e7a4e521917..2239e6dd4d4c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -83,6 +83,9 @@ struct mem_cgroup *root_mem_cgroup __read_mostly;
 /* Socket memory accounting disabled? */
 static bool cgroup_memory_nosocket;
 
+/* Kernel memory accounting disabled? */
+static bool cgroup_memory_nokmem;
+
 /* Whether the swap controller is active */
 #ifdef CONFIG_MEMCG_SWAP
 int do_swap_account __read_mostly;
@@ -2925,8 +2928,8 @@ static int memcg_propagate_kmem(struct mem_cgroup *memcg)
          * onlined after this point, because it has at least one child
          * already.
          */
-        if (cgroup_subsys_on_dfl(memory_cgrp_subsys) ||
-            memcg_kmem_online(parent))
+        if (memcg_kmem_online(parent) ||
+            (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nokmem))
                 ret = memcg_online_kmem(memcg);
         mutex_unlock(&memcg_limit_mutex);
         return ret;
@@ -5638,6 +5641,8 @@ static int __init cgroup_memory(char *s)
                         continue;
                 if (!strcmp(token, "nosocket"))
                         cgroup_memory_nosocket = true;
+                if (!strcmp(token, "nokmem"))
+                        cgroup_memory_nokmem = true;
         }
         return 0;
 }