Merge branch 'mm-bpf-kfuncs-to-access-memcg-data'

Roman Gushchin says:

====================
mm: bpf kfuncs to access memcg data

Introduce kfuncs to simplify the access to the memcg data.
These kfuncs can be used to accelerate monitoring use cases and
for implementing custom OOM policies once BPF OOM is landed.

This patchset was separated out from the BPF OOM patchset to simplify
the logistics and accelerate the landing of the part which is useful
by itself. No functional changes since BPF OOM v2.

v4:
  - refactored memcg vm event and stat item idx checks (by Alexei)

v3:
  - dropped redundant kfuncs flags (by Alexei)
  - fixed kdocs warnings (by Alexei)
  - merged memcg stats access patches into one (by Alexei)
  - restored root memcg usage reporting, added a comment
  - added checks for enum boundaries
  - added Shakeel and JP as co-maintainers (by Shakeel)

v2:
  - added mem_cgroup_disabled() checks (by Shakeel B.)
  - added special handling of the root memcg in bpf_mem_cgroup_usage()
  (by Shakeel B.)
  - minor fixes in the kselftest (by Shakeel B.)
  - added a MAINTAINERS entry (by Shakeel B.)

v1:
  https://lore.kernel.org/bpf/87ike29s5r.fsf@linux.dev/T/#t
====================

Link: https://patch.msgid.link/20251223044156.208250-1-roman.gushchin@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 0651865a4564..6a5d65487b70 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -949,7 +949,12 @@ static inline void mod_memcg_page_state(struct page *page,
 	rcu_read_unlock();
 }
 
+unsigned long memcg_events(struct mem_cgroup *memcg, int event);
+unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap);
 unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx);
+unsigned long memcg_page_state_output(struct mem_cgroup *memcg, int item);
+bool memcg_stat_item_valid(int idx);
+bool memcg_vm_event_item_valid(enum vm_event_item idx);
 unsigned long lruvec_page_state(struct lruvec *lruvec, enum node_stat_item idx);
 unsigned long lruvec_page_state_local(struct lruvec *lruvec,
 				      enum node_stat_item idx);
@@ -1373,6 +1378,21 @@ static inline unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx)
 	return 0;
 }
 
+static inline unsigned long memcg_page_state_output(struct mem_cgroup *memcg, int item)
+{
+	return 0;
+}
+
+static inline bool memcg_stat_item_valid(int idx)
+{
+	return false;
+}
+
+static inline bool memcg_vm_event_item_valid(enum vm_event_item idx)
+{
+	return false;
+}
+
 static inline unsigned long lruvec_page_state(struct lruvec *lruvec,
 					      enum node_stat_item idx)
 {