[RFC PATCH 3/3] docs/cgroup: document memory.lru_gen interface

[Jiayuan Chen <jiayuan.chen@linux.dev>]

From: Jiayuan Chen <jiayuan.chen@shopee.com>

Add documentation for the memory.lru_gen interface in cgroup v2.
For detailed information about MGLRU and the command format, refer
to the multi-gen LRU documentation.

Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
---
 Documentation/admin-guide/cgroup-v2.rst | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 7f5b59d95fce..bb3ca7ffd600 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1426,6 +1426,23 @@ PAGE_SIZE multiple when read back.
 	This means that the networking layer will not adapt based on
 	reclaim induced by memory.reclaim.
 
+  memory.lru_gen
+	A read-write file that exists when CONFIG_LRU_GEN is enabled.
+
+	Reading this file displays the multi-gen LRU information for
+	this memcg, including generation numbers, page counts for
+	anonymous and file pages across all NUMA nodes.
+
+	Writing to this file allows performing aging or eviction
+	operations on this memcg. The format is::
+
+	  echo '<cmd> <node_id> <seq> [<swappiness> [<opt>]]' > memory.lru_gen
+
+	This interface provides the same functionality as the debugfs
+	lru_gen interface but operates directly on the cgroup without
+	requiring the memcg_id. For detailed documentation of the
+	command format and MGLRU, see Documentation/admin-guide/mm/multigen_lru.rst.
+
 The following nested keys are defined.
 
 	  ==========            ================================
-- 
2.43.0