From c06173bae3630cd1f953e69c4dd8df98904892a5 Mon Sep 17 00:00:00 2001

Message-Id: <c06173bae3630cd1f953e69c4dd8df98904892a5@dist-git>

From: Pavel Hrdina <phrdina@redhat.com>

Date: Mon, 1 Jul 2019 17:08:24 +0200

Subject: [PATCH] util: vircgroupv2: stop enabling missing controllers with

 systemd

MIME-Version: 1.0

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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@redhat.com>

Reviewed-by: Ján Tomko <jtomko@redhat.com>

(cherry picked from commit 62dd4d25a2bc5ee33ed22728dc79a5da99906748)

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1689297

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>

Message-Id: <273d20b3ced7f8b3ea0cc761cff25601f03e318f.1561993100.git.phrdina@redhat.com>

Reviewed-by: Ján Tomko <jtomko@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 a7fb595bce..3c99934b25 100644

--- a/src/util/vircgroup.c

+++ b/src/util/vircgroup.c

@@ -1075,7 +1075,7 @@ 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 a825dc4be7..2b5be21a76 100644

--- a/src/util/vircgroupbackend.h

+++ b/src/util/vircgroupbackend.h

@@ -35,6 +35,9 @@ 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 b0ed889cc8..749efa199b 100644

--- a/src/util/vircgroupv2.c

+++ b/src/util/vircgroupv2.c

@@ -394,6 +394,11 @@ 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);

-- 

2.22.0