Merge branch 'bpf, mm: introduce cgroup.memory=nobpf'

Yafang Shao says:

====================

The bpf memory accouting has some known problems in contianer
environment,

- The container memory usage is not consistent if there's pinned bpf
  program
  After the container restart, the leftover bpf programs won't account
  to the new generation, so the memory usage of the container is not
  consistent. This issue can be resolved by introducing selectable
  memcg, but we don't have an agreement on the solution yet. See also
  the discussions at https://lwn.net/Articles/905150/ .

- The leftover non-preallocated bpf map can't be limited
  The leftover bpf map will be reparented, and thus it will be limited by
  the parent, rather than the container itself. Furthermore, if the
  parent is destroyed, it be will limited by its parent's parent, and so
  on. It can also be resolved by introducing selectable memcg.

- The memory dynamically allocated in bpf prog is charged into root memcg
  only
  Nowdays the bpf prog can dynamically allocate memory, for example via
  bpf_obj_new(), but it only allocate from the global bpf_mem_alloc
  pool, so it will charge into root memcg only. That needs to be
  addressed by a new proposal.

So let's give the container user an option to disable bpf memory accouting.

The idea of "cgroup.memory=nobpf" is originally by Tejun[1].

[1]. https://lwn.net/ml/linux-mm/YxjOawzlgE458ezL@slm.duckdns.org/

Changes,
v1->v2:
- squash patches (Roman)
- commit log improvement in patch #2. (Johannes)
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 85dc9b88ea37..1e38e99998c7 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1754,6 +1754,12 @@ struct obj_cgroup *get_obj_cgroup_from_page(struct page *page);
 int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size);
 void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size);
 
+extern struct static_key_false memcg_bpf_enabled_key;
+static inline bool memcg_bpf_enabled(void)
+{
+	return static_branch_likely(&memcg_bpf_enabled_key);
+}
+
 extern struct static_key_false memcg_kmem_enabled_key;
 
 static inline bool memcg_kmem_enabled(void)
@@ -1832,6 +1838,11 @@ static inline struct obj_cgroup *get_obj_cgroup_from_page(struct page *page)
 	return NULL;
 }
 
+static inline bool memcg_bpf_enabled(void)
+{
+	return false;
+}
+
 static inline bool memcg_kmem_enabled(void)
 {
 	return false;