net: set proper memcg for net_init hooks allocations

__register_pernet_operations() executes init hook of registered
pernet_operation structure in all existing net namespaces.

Typically, these hooks are called by a process associated with the
specified net namespace, and all __GFP_ACCOUNT marked allocation are
accounted for corresponding container/memcg.

However __register_pernet_operations() calls the hooks in the same
context, and as a result all marked allocations are accounted to one memcg
for all processed net namespaces.

This patch adjusts active memcg for each net namespace and helps to
account memory allocated inside ops_init() into the proper memcg.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Vasily Averin <[email protected]>
Acked-by: Roman Gushchin <[email protected]>
Acked-by: Shakeel Butt <[email protected]>
Cc: Michal Koutný <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Florian Westphal <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kefeng Wang <[email protected]>
Cc: Linux Kernel Functional Testing <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Naresh Kamboju <[email protected]>
Cc: Qian Cai <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 0ec2f5906a27..6b9f19122ec1 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -18,6 +18,7 @@
 #include <linux/user_namespace.h>
 #include <linux/net_namespace.h>
 #include <linux/sched/task.h>
+#include <linux/sched/mm.h>
 #include <linux/uidgid.h>
 #include <linux/cookie.h>
 
@@ -1143,7 +1144,13 @@ static int __register_pernet_operations(struct list_head *list,
 		 * setup_net() and cleanup_net() are not possible.
 		 */
 		for_each_net(net) {
+			struct mem_cgroup *old, *memcg;
+
+			memcg = mem_cgroup_or_root(get_mem_cgroup_from_obj(net));
+			old = set_active_memcg(memcg);
 			error = ops_init(ops, net);
+			set_active_memcg(old);
+			mem_cgroup_put(memcg);
 			if (error)
 				goto out_undo;
 			list_add_tail(&net->exit_list, &net_exit_list);