path: root/kernel/cgroup.c
diff options
authorTejun Heo <>2016-03-03 09:58:01 -0500
committerTejun Heo <>2016-03-03 09:58:01 -0500
commit04313591ae487da8b5781a0d8d444073a3fdee0d (patch)
treeeb0582020cd0369d8767c813149b9eec7dddde8e /kernel/cgroup.c
parent5ced2518bd3e3a4f01e2122122211f217cd99f4f (diff)
cgroup: allocate 2x cgrp_cset_links when setting up a new root
During prep, cgroup_setup_root() allocates cgrp_cset_links matching the number of existing css_sets to later link the new root. This is fine for now as the only operation which can happen inbetween is rebind_subsystems() and rebinding of empty subsystems doesn't create new css_sets. However, while not yet allowed, with the recent reimplementation, rebind_subsystems() can rebind subsystems with descendant csses and thus can create new css_sets. This patch makes cgroup_setup_root() allocate 2x of the existing css_sets so that later use of live subsystem rebinding doesn't blow up. Signed-off-by: Tejun Heo <> Acked-by: Zefan Li <>
Diffstat (limited to 'kernel/cgroup.c')
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 58e02e9aa970..40ed329482dd 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1915,10 +1915,11 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
* We're accessing css_set_count without locking css_set_lock here,
* but that's OK - it can only be increased by someone holding
- * cgroup_lock, and that's us. The worst that can happen is that we
- * have some link structures left over
+ * cgroup_lock, and that's us. Later rebinding may disable
+ * controllers on the default hierarchy and thus create new csets,
+ * which can't be more than the existing ones. Allocate 2x.
- ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
+ ret = allocate_cgrp_cset_links(2 * css_set_count, &tmp_links);
if (ret)
goto cancel_ref;