linux-kernel - [PATCH v2 11/23] mm: introduce BPF kfunc to access memory events

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Message-ID: <20251027232206.473085-1-roman.gushchin@linux.dev>
Date: Mon, 27 Oct 2025 16:21:54 -0700
From: Roman Gushchin <roman.gushchin@...ux.dev>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org,
	Alexei Starovoitov <ast@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...nel.org>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Johannes Weiner <hannes@...xchg.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	JP Kobryn <inwardvessel@...il.com>,
	linux-mm@...ck.org,
	cgroups@...r.kernel.org,
	bpf@...r.kernel.org,
	Martin KaFai Lau <martin.lau@...nel.org>,
	Song Liu <song@...nel.org>,
	Kumar Kartikeya Dwivedi <memxor@...il.com>,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH v2 11/23] mm: introduce BPF kfunc to access memory events

From: JP Kobryn <inwardvessel@...il.com>

Introduce BPF kfunc to access memory events, e.g.:
MEMCG_LOW, MEMCG_MAX, MEMCG_OOM, MEMCG_OOM_KILL etc.

Signed-off-by: JP Kobryn <inwardvessel@...il.com>
---
 mm/bpf_memcontrol.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/mm/bpf_memcontrol.c b/mm/bpf_memcontrol.c
index 387255b8ab88..458ad022b036 100644
--- a/mm/bpf_memcontrol.c
+++ b/mm/bpf_memcontrol.c
@@ -99,6 +99,23 @@ __bpf_kfunc unsigned long bpf_mem_cgroup_usage(struct mem_cgroup *memcg)
 	return page_counter_read(&memcg->memory);
 }
 
+/**
+ * bpf_mem_cgroup_events - Read memory cgroup's page state counter
+ * bpf_mem_cgroup_memory_events - Read memory cgroup's memory event value
+ * @memcg: memory cgroup
+ * @event: memory event id
+ *
+ * Returns current memory event count.
+ */
+__bpf_kfunc unsigned long bpf_mem_cgroup_memory_events(struct mem_cgroup *memcg,
+						enum memcg_memory_event event)
+{
+	if (event >= MEMCG_NR_MEMORY_EVENTS)
+		return (unsigned long)-1;
+
+	return atomic_long_read(&memcg->memory_events[event]);
+}
+
 /**
  * bpf_mem_cgroup_page_state - Read memory cgroup's page state counter
  * @memcg: memory cgroup
@@ -133,6 +150,7 @@ BTF_ID_FLAGS(func, bpf_get_mem_cgroup, KF_ACQUIRE | KF_RET_NULL | KF_RCU)
 BTF_ID_FLAGS(func, bpf_put_mem_cgroup, KF_RELEASE)
 
 BTF_ID_FLAGS(func, bpf_mem_cgroup_vm_events, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_mem_cgroup_memory_events, KF_TRUSTED_ARGS)
 BTF_ID_FLAGS(func, bpf_mem_cgroup_usage, KF_TRUSTED_ARGS)
 BTF_ID_FLAGS(func, bpf_mem_cgroup_page_state, KF_TRUSTED_ARGS)
 BTF_ID_FLAGS(func, bpf_mem_cgroup_flush_stats, KF_TRUSTED_ARGS | KF_SLEEPABLE)
-- 
2.51.0