The commit is pushed to "branch-rh7-3.10.0-1127.18.2.vz7.163.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1127.18.2.el7
------>
commit 2c7e88541f87587f184eb3e23ba44e89428ed7a6
Author: Valeriy Vdovin <[email protected]>
Date: Thu Aug 6 08:32:28 2020 +0300
ve/cgroup: At cgroup_mark(unmark)_ve_roots skip non-virtualized roots
During container start there might be a situation when not all cgroup
hierarchies get virtualized by container manager (like vzctl). By
virtualizing a cgroup hierarchy I mean creation of sub-directory within
a particular mounted cgroup. When container starts it looks in css set
of it's init process to list all affilated cgroups and perform actions
on each. But non-virtualized cgroups will also be present in init's css_set
and they should not be touched from inside of any non root ve.
Signed-off-by: Valeriy Vdovin <[email protected]>
---
kernel/cgroup.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 64cbc5d..55713a0 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4615,6 +4615,18 @@ static struct cftype *get_cftype_by_name(const char
*name)
}
#ifdef CONFIG_VE
+static inline bool is_virtualized_cgroup(struct cgroup *cgrp)
+{
+ lockdep_assert_held(&cgroup_mutex);
+ if (cgrp->root->subsys_mask)
+ return true;
+
+ if (!strcmp(cgrp->root->name, "systemd"))
+ return true;
+
+ return false;
+}
+
int cgroup_mark_ve_roots(struct ve_struct *ve)
{
struct cgroup *cgrp, *tmp;
@@ -4630,6 +4642,17 @@ int cgroup_mark_ve_roots(struct ve_struct *ve)
mutex_lock(&cgroup_mutex);
for_each_active_root(root) {
cgrp = css_cgroup_from_root(ve->root_css_set, root);
+
+ /*
+ * At container start, vzctl creates special cgroups to serve
+ * as virtualized cgroup roots. They are bind-mounted on top
+ * of original cgroup mount point in container namespace. But
+ * not all cgroup mounts undergo this procedure. We should
+ * skip cgroup mounts that are not virtualized.
+ */
+ if (!is_virtualized_cgroup(cgrp))
+ continue;
+
rcu_assign_pointer(cgrp->ve_owner, ve);
set_bit(CGRP_VE_ROOT, &cgrp->flags);
@@ -4679,6 +4702,14 @@ void cgroup_unmark_ve_roots(struct ve_struct *ve)
mutex_lock(&cgroup_mutex);
for_each_active_root(root) {
cgrp = css_cgroup_from_root(ve->root_css_set, root);
+
+ /*
+ * For this line see comments in
+ * cgroup_mark_ve_roots
+ */
+ if (!is_virtualized_cgroup(cgrp))
+ continue;
+
dget(cgrp->dentry);
list_add_tail(&cgrp->cft_q_node, &pending);
}
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