[PATCH RFC 4/4] mm/ksm: add automerging documentation

[Oleksandr Natalenko]

Document KSM "always" mode kernel cmdline option as well as
corresponding sysfs knob.

Signed-off-by: Oleksandr Natalenko <oleksandr@xxxxxxxxxx>
---
 Documentation/admin-guide/kernel-parameters.txt | 7 +++++++
 Documentation/admin-guide/mm/ksm.rst            | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2b8ee90bb644..510766a3fa05 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2008,6 +2008,13 @@
 			0: force disabled
 			1: force enabled
 
+	ksm_mode=
+			[KNL]
+			Format: [madvise|always]
+			Default: madvise
+			Can be used to control the default behavior of the system
+			with respect to merging anonymous memory.
+
 	kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
 			Default is 0 (don't ignore, but inject #GP)
 
diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst
index 9303786632d1..9af730640da7 100644
--- a/Documentation/admin-guide/mm/ksm.rst
+++ b/Documentation/admin-guide/mm/ksm.rst
@@ -78,6 +78,13 @@ KSM daemon sysfs interface
 The KSM daemon is controlled by sysfs files in ``/sys/kernel/mm/ksm/``,
 readable by all but writable only by root:
 
+mode
+        * set madvise to deduplicate only madvised memory
+        * set always to allow deduplicating all the anonymous memory
+          (applies to newly allocated memory only)
+
+        Default: madvise (maintains old behaviour)
+
 pages_to_scan
         how many pages to scan before ksmd goes to sleep
         e.g. ``echo 100 > /sys/kernel/mm/ksm/pages_to_scan``.
-- 
2.21.0