From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Wed, 17 Mar 2021 08:24:56 +0000 (+0100)
Subject: cgroups: ignore unused controllers
X-Git-Tag: lxc-5.0.0~259^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6159413bc9dfe2dc2d7598dedb36df45e5b40747;p=thirdparty%2Flxc.git

cgroups: ignore unused controllers

Someone might have created a name=<controller> controller after the
container has started and so the container doesn't make use of this
controller.

Link: https://github.com/lxc/lxd/issues/8577
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---

diff --git a/src/lxc/cgroups/cgfsng.c b/src/lxc/cgroups/cgfsng.c
index 46ed69714..f66790a4d 100644
--- a/src/lxc/cgroups/cgfsng.c
+++ b/src/lxc/cgroups/cgfsng.c
@@ -2363,9 +2363,17 @@ __cgfsng_ops static bool cgfsng_attach(struct cgroup_ops *ops,
 		}
 
 		path = lxc_cmd_get_cgroup_path(name, lxcpath, h->controllers[0]);
-		/* not running */
-		if (!path)
-			return false;
+		if (!path) {
+			/*
+			 * Someone might have created a name=<controller>
+			 * controller after the container has started and so
+			 * the container doesn't make use of this controller.
+			 *
+			 * Link: https://github.com/lxc/lxd/issues/8577
+			 */
+			TRACE("Skipping unused %s controller", maybe_empty(h->controllers[0]));
+			continue;
+		}
 
 		fullpath = build_full_cgpath_from_monitorpath(h, path, "cgroup.procs");
 		ret = lxc_write_to_file(fullpath, pidstr, len, false, 0666);