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Diffstat (limited to 'src/nspawn/nspawn-cgroup.c')
-rw-r--r--src/nspawn/nspawn-cgroup.c77
1 files changed, 34 insertions, 43 deletions
diff --git a/src/nspawn/nspawn-cgroup.c b/src/nspawn/nspawn-cgroup.c
index d51585a652..d8a39a6959 100644
--- a/src/nspawn/nspawn-cgroup.c
+++ b/src/nspawn/nspawn-cgroup.c
@@ -1,22 +1,4 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
-/***
- This file is part of systemd.
-
- Copyright 2015 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
#include <sys/mount.h>
@@ -154,44 +136,53 @@ finish:
return r;
}
-int create_subcgroup(pid_t pid, CGroupUnified unified_requested) {
+int create_subcgroup(pid_t pid, bool keep_unit, CGroupUnified unified_requested) {
_cleanup_free_ char *cgroup = NULL;
- const char *child;
- int r;
CGroupMask supported;
+ const char *payload;
+ int r;
- /* In the unified hierarchy inner nodes may only contain
- * subgroups, but not processes. Hence, if we running in the
- * unified hierarchy and the container does the same, and we
- * did not create a scope unit for the container move us and
- * the container into two separate subcgroups. */
-
- if (unified_requested == CGROUP_UNIFIED_NONE)
- return 0;
-
- r = cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER);
- if (r < 0)
- return log_error_errno(r, "Failed to determine whether the systemd controller is unified: %m");
- if (r == 0)
- return 0;
+ assert(pid > 1);
+
+ /* In the unified hierarchy inner nodes may only contain subgroups, but not processes. Hence, if we running in
+ * the unified hierarchy and the container does the same, and we did not create a scope unit for the container
+ * move us and the container into two separate subcgroups.
+ *
+ * Moreover, container payloads such as systemd try to manage the cgroup they run in in full (i.e. including
+ * its attributes), while the host systemd will only delegate cgroups for children of the cgroup created for a
+ * delegation unit, instead of the cgroup itself. This means, if we'd pass on the cgroup allocated from the
+ * host systemd directly to the payload, the host and payload systemd might fight for the cgroup
+ * attributes. Hence, let's insert an intermediary cgroup to cover that case too.
+ *
+ * Note that we only bother with the main hierarchy here, not with any secondary ones. On the unified setup
+ * that's fine because there's only one hiearchy anyway and controllers are enabled directly on it. On the
+ * legacy setup, this is fine too, since delegation of controllers is generally not safe there, hence we won't
+ * do it. */
r = cg_mask_supported(&supported);
if (r < 0)
return log_error_errno(r, "Failed to determine supported controllers: %m");
- r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, 0, &cgroup);
+ if (keep_unit)
+ r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, 0, &cgroup);
+ else
+ r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, pid, &cgroup);
if (r < 0)
return log_error_errno(r, "Failed to get our control group: %m");
- child = strjoina(cgroup, "/payload");
- r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, child, pid);
+ payload = strjoina(cgroup, "/payload");
+ r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, payload, pid);
if (r < 0)
- return log_error_errno(r, "Failed to create %s subcgroup: %m", child);
+ return log_error_errno(r, "Failed to create %s subcgroup: %m", payload);
- child = strjoina(cgroup, "/supervisor");
- r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, child, 0);
- if (r < 0)
- return log_error_errno(r, "Failed to create %s subcgroup: %m", child);
+ if (keep_unit) {
+ const char *supervisor;
+
+ supervisor = strjoina(cgroup, "/supervisor");
+ r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, supervisor, 0);
+ if (r < 0)
+ return log_error_errno(r, "Failed to create %s subcgroup: %m", supervisor);
+ }
/* Try to enable as many controllers as possible for the new payload. */
(void) cg_enable_everywhere(supported, supported, cgroup);