[libvirt] [PATCH 2/2] util: vircgroupv2: stop enabling missing controllers with systemd
Because of a systemd delegation policy [1] we should not write to any
cgroups files owned by systemd which in case of cgroups v2 includes
'cgroups.subtree_control'.
systemd will enable controllers automatically for us to have them
available for VM cgroups.
[1] <https://github.com/systemd/systemd/blob/master/docs/CGROUP_DELEGATION.md>
Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com>
---
src/util/vircgroup.c | 2 +-
src/util/vircgroupbackend.h | 3 +++
src/util/vircgroupv2.c | 5 +++++
3 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
index e4675a0977..268e4013e3 100644
--- a/src/util/vircgroup.c
+++ b/src/util/vircgroup.c
@@ -1082,7 +1082,7 @@ virCgroupEnableMissingControllers(char *path,
&tmp) < 0)
goto cleanup;
- if (virCgroupMakeGroup(parent, tmp, true, VIR_CGROUP_NONE) < 0) {
+ if (virCgroupMakeGroup(parent, tmp, true, VIR_CGROUP_SYSTEMD) < 0) {
virCgroupFree(&tmp);
goto cleanup;
}
diff --git a/src/util/vircgroupbackend.h b/src/util/vircgroupbackend.h
index e58e327c68..a91719f89d 100644
--- a/src/util/vircgroupbackend.h
+++ b/src/util/vircgroupbackend.h
@@ -34,6 +34,9 @@ typedef enum {
* attaching tasks
*/
VIR_CGROUP_THREAD = 1 << 1, /* cgroup v2 handles threads differently */
+ VIR_CGROUP_SYSTEMD = 1 << 2, /* with systemd and cgroups v2 we cannot
+ * manually enable controllers that systemd
+ * doesn't know how to delegate */
} virCgroupBackendFlags;
typedef enum {
diff --git a/src/util/vircgroupv2.c b/src/util/vircgroupv2.c
index b3297dbb13..9d8a38925a 100644
--- a/src/util/vircgroupv2.c
+++ b/src/util/vircgroupv2.c
@@ -395,6 +395,11 @@ virCgroupV2MakeGroup(virCgroupPtr parent ATTRIBUTE_UNUSED,
VIR_AUTOFREE(char *) path = NULL;
int controller;
+ if (flags & VIR_CGROUP_SYSTEMD) {
+ VIR_DEBUG("Running with systemd so we should not create cgroups
ourselves.");
+ return 0;
+ }
+
VIR_DEBUG("Make group %s", group->path);
controller = virCgroupV2GetAnyController(group);
--
2.21.0