cgroup: get mode by checking /sys/fs/cgroup mount point

[pve-common.git] / src / PVE / CGroup.pm

diff --git a/src/PVE/CGroup.pm b/src/PVE/CGroup.pm
index 92a065464dea4077b5eb95b7d73582925fc9c762..45c0788fef3463950ccf3021dccf989381c7c865 100644 (file)
--- a/src/PVE/CGroup.pm
+++ b/src/PVE/CGroup.pm
@@ -86,21 +86,30 @@ sub get_cgroup_controllers() {
 my $CGROUP_MODE = undef;
 # Figure out which cgroup mode we're operating under:
 #
-# Returns 1 if cgroupv1 controllers exist (hybrid or legacy mode), and 2 in a
-# cgroupv2-only environment.
+# For this we check the file system type of `/sys/fs/cgroup` as it may well be possible that some
+# additional cgroupv1 mount points have been created by tools such as `systemd-nspawn`, or
+# manually.
+#
+# Returns 1 for what we consider the hybrid layout, 2 for what we consider the unified layout.
 #
 # NOTE: To fully support a hybrid layout it is better to use functions like
-# `cpuset_controller_path`.
+# `cpuset_controller_path` and not rely on this value for anything involving paths.
 #
 # This is a function, not a method!
 sub cgroup_mode() {
     if (!defined($CGROUP_MODE)) {
-       my ($v1, $v2) = get_cgroup_controllers();
-       if (keys %$v1) {
-           # hybrid or legacy mode
-           $CGROUP_MODE = 1;
-       } elsif ($v2) {
-           $CGROUP_MODE = 2;
+       my $mounts = PVE::ProcFSTools::parse_proc_mounts();
+       for my $entry (@$mounts) {
+           my ($what, $dir, $fstype, $opts) = @$entry;
+           if ($dir eq '/sys/fs/cgroup') {
+               if ($fstype eq 'cgroup2') {
+                   $CGROUP_MODE = 2;
+                   last;
+               } else {
+                   $CGROUP_MODE = 1;
+                   last;
+               }
+           }
        }
     }