[RFC 5/5] Docs/cgroup-v2: add cgroup.memsw_account_on_dfl Documentation

[Jingxiang Zeng <jingxiangzeng.cas@gmail.com>]

From: Zeng Jingxiang <linuszeng@tencent.com>

Add documentation descriptions for cgroup.memsw_account_on_dfl and
CONFIG_MEMSW_ACCOUNT_ON_DFL.

Signed-off-by: Zeng Jingxiang <linuszeng@tencent.com>
---
 Documentation/admin-guide/cgroup-v2.rst       | 21 +++++++++++++++----
 .../admin-guide/kernel-parameters.txt         |  7 +++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 53ada5c2620a..58869279f0a9 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1704,8 +1704,14 @@ The following nested keys are defined.
 	A read-only single value file which exists on non-root
 	cgroups.
 
-	The total amount of swap currently being used by the cgroup
-	and its descendants.
+	If memsw_account_on_dfl and CONFIG_MEMSW_ACCOUNT_ON_DFL is not
+	enabled (the default), this interface represents the total
+	amount of swap currently being used by the cgroup and its
+	descendants.
+
+	If memsw_account_on_dfl or CONFIG_MEMSW_ACCOUNT_ON_DFL is enabled,
+	this interface represents the total amount of memory+swap
+	currently being used by the cgroup and its descendants.
 
   memory.swap.high
 	A read-write single value file which exists on non-root
@@ -1737,8 +1743,15 @@ The following nested keys are defined.
 	A read-write single value file which exists on non-root
 	cgroups.  The default is "max".
 
-	Swap usage hard limit.  If a cgroup's swap usage reaches this
-	limit, anonymous memory of the cgroup will not be swapped out.
+	If memsw_account_on_dfl and CONFIG_MEMSW_ACCOUNT_ON_DFL is not
+	enabled (the default), this interface represents the hard limit
+	of swap usage. If a cgroup's swap usage reaches this limit,
+	anonymous memory of the cgroup will not be swapped out.
+
+	If memsw_account_on_dfl or CONFIG_MEMSW_ACCOUNT_ON_DFL is enabled,
+	this interface represents the hard limit of memory+swap usage.
+	If a cgroup's memory+swap usage reaches this limit, anonymous
+	memory of the cgroup will not be swapped out.
 
   memory.swap.max.effective
 	A read-only single value file which exists on non-root cgroups.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2758bc124f16..0aa9e4f85b51 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -644,6 +644,13 @@
 			nokmem -- Disable kernel memory accounting.
 			nobpf -- Disable BPF memory accounting.
 
+	cgroup.memsw_account_on_dfl= [KNL] Enable memory+swap account on cgroupv2.
+			Format: { "0" | "1" }
+			0 - memory.swap.current and memory.swap.max represents the
+				usage/limit of swap.
+			1 - memory.swap.current and memory.swap.max represents the
+				usage/limit of memory+swap.
+
 	checkreqprot=	[SELINUX] Set initial checkreqprot flag value.
 			Format: { "0" | "1" }
 			See security/selinux/Kconfig help text.
-- 
2.41.1