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-rw-r--r--block/blk-cgroup.c8
-rw-r--r--include/linux/cgroup.h15
-rw-r--r--kernel/cgroup.c12
-rw-r--r--kernel/cgroup_freezer.c8
-rw-r--r--kernel/events/core.c7
-rw-r--r--mm/memcontrol.c7
-rw-r--r--net/core/netprio_cgroup.c12
-rw-r--r--net/sched/cls_cgroup.c9
-rw-r--r--security/device_cgroup.c9
9 files changed, 85 insertions, 2 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index f3b44a6..cafcd74 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -737,6 +737,14 @@ struct cgroup_subsys blkio_subsys = {
.subsys_id = blkio_subsys_id,
.base_cftypes = blkcg_files,
.module = THIS_MODULE,
+
+ /*
+ * blkio subsystem is utterly broken in terms of hierarchy support.
+ * It treats all cgroups equally regardless of where they're
+ * located in the hierarchy - all cgroups are treated as if they're
+ * right below the root. Fix it and remove the following.
+ */
+ .broken_hierarchy = true,
};
EXPORT_SYMBOL_GPL(blkio_subsys);
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index c90eaa8..68e8df7 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -496,6 +496,21 @@ struct cgroup_subsys {
*/
bool __DEPRECATED_clear_css_refs;
+ /*
+ * If %false, this subsystem is properly hierarchical -
+ * configuration, resource accounting and restriction on a parent
+ * cgroup cover those of its children. If %true, hierarchy support
+ * is broken in some ways - some subsystems ignore hierarchy
+ * completely while others are only implemented half-way.
+ *
+ * It's now disallowed to create nested cgroups if the subsystem is
+ * broken and cgroup core will emit a warning message on such
+ * cases. Eventually, all subsystems will be made properly
+ * hierarchical and this will go away.
+ */
+ bool broken_hierarchy;
+ bool warned_broken_hierarchy;
+
#define MAX_CGROUP_TYPE_NAMELEN 32
const char *name;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 7981850..b7d9606 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3954,8 +3954,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags);
for_each_subsys(root, ss) {
- struct cgroup_subsys_state *css = ss->create(cgrp);
+ struct cgroup_subsys_state *css;
+ css = ss->create(cgrp);
if (IS_ERR(css)) {
err = PTR_ERR(css);
goto err_destroy;
@@ -3969,6 +3970,15 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
/* At error, ->destroy() callback has to free assigned ID. */
if (clone_children(parent) && ss->post_clone)
ss->post_clone(cgrp);
+
+ if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
+ parent->parent) {
+ pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
+ current->comm, current->pid, ss->name);
+ if (!strcmp(ss->name, "memory"))
+ pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
+ ss->warned_broken_hierarchy = true;
+ }
}
list_add(&cgrp->sibling, &cgrp->parent->children);
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 3649fc6..b1724ce 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -373,4 +373,12 @@ struct cgroup_subsys freezer_subsys = {
.can_attach = freezer_can_attach,
.fork = freezer_fork,
.base_cftypes = files,
+
+ /*
+ * freezer subsys doesn't handle hierarchy at all. Frozen state
+ * should be inherited through the hierarchy - if a parent is
+ * frozen, all its children should be frozen. Fix it and remove
+ * the following.
+ */
+ .broken_hierarchy = true,
};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index b7935fc..f18a0a5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7285,5 +7285,12 @@ struct cgroup_subsys perf_subsys = {
.destroy = perf_cgroup_destroy,
.exit = perf_cgroup_exit,
.attach = perf_cgroup_attach,
+
+ /*
+ * perf_event cgroup doesn't handle nesting correctly.
+ * ctx->nr_cgroups adjustments should be propagated through the
+ * cgroup hierarchy. Fix it and remove the following.
+ */
+ .broken_hierarchy = true,
};
#endif /* CONFIG_CGROUP_PERF */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 795e525..a72f2ff 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4973,6 +4973,13 @@ mem_cgroup_create(struct cgroup *cont)
} else {
res_counter_init(&memcg->res, NULL);
res_counter_init(&memcg->memsw, NULL);
+ /*
+ * Deeper hierachy with use_hierarchy == false doesn't make
+ * much sense so let cgroup subsystem know about this
+ * unfortunate state in our controller.
+ */
+ if (parent && parent != root_mem_cgroup)
+ mem_cgroup_subsys.broken_hierarchy = true;
}
memcg->last_scanned_node = MAX_NUMNODES;
INIT_LIST_HEAD(&memcg->oom_notify);
diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index c75e3f9..34f3615 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -330,7 +330,17 @@ struct cgroup_subsys net_prio_subsys = {
.subsys_id = net_prio_subsys_id,
#endif
.base_cftypes = ss_files,
- .module = THIS_MODULE
+ .module = THIS_MODULE,
+
+ /*
+ * net_prio has artificial limit on the number of cgroups and
+ * disallows nesting making it impossible to co-mount it with other
+ * hierarchical subsystems. Remove the artificially low PRIOIDX_SZ
+ * limit and properly nest configuration such that children follow
+ * their parents' configurations by default and are allowed to
+ * override and remove the following.
+ */
+ .broken_hierarchy = true,
};
static int netprio_device_event(struct notifier_block *unused,
diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index 7743ea8..907daf9 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -82,6 +82,15 @@ struct cgroup_subsys net_cls_subsys = {
#endif
.base_cftypes = ss_files,
.module = THIS_MODULE,
+
+ /*
+ * While net_cls cgroup has the rudimentary hierarchy support of
+ * inheriting the parent's classid on cgroup creation, it doesn't
+ * properly propagates config changes in ancestors to their
+ * descendents. A child should follow the parent's configuration
+ * but be allowed to override it. Fix it and remove the following.
+ */
+ .broken_hierarchy = true,
};
struct cls_cgroup_head {
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 442204c..4b877a9 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -457,6 +457,15 @@ struct cgroup_subsys devices_subsys = {
.destroy = devcgroup_destroy,
.subsys_id = devices_subsys_id,
.base_cftypes = dev_cgroup_files,
+
+ /*
+ * While devices cgroup has the rudimentary hierarchy support which
+ * checks the parent's restriction, it doesn't properly propagates
+ * config changes in ancestors to their descendents. A child
+ * should only be allowed to add more restrictions to the parent's
+ * configuration. Fix it and remove the following.
+ */
+ .broken_hierarchy = true,
};
int __devcgroup_inode_permission(struct inode *inode, int mask)
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