cgroups.7: Mention cgroup.sane_behavior file

The cgroup.sane_behavior file returns the hard-coded value "0" and
is kept for legacy purposes. Mention this in the man-page.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man7/cgroups.7 b/man7/cgroups.7
index 971bfb1eab30a8c4fb11c89c9fafbbaf60500739..68440dfaa678fa40d788c760e5d9a54ff2289b12 100644 (file)
--- a/man7/cgroups.7
+++ b/man7/cgroups.7
@@ -87,6 +87,10 @@ Initially marked experimental, and hidden behind the
 mount option, the new version (cgroups version 2)
 was eventually made official with the release of Linux 4.5.
 Differences between the two versions are described in the text below.
+The file
+.IR cgroup.sane_behavior ,
+present in cgroups v1, is a relic of this mount option. The file
+always reports "0" and is only retained for backward compatibility.
 .PP
 Although cgroups v2 is intended as a replacement for cgroups v1,
 the older system continues to exist