The task cannot modify cgroups if we have already acquired the css_set_lock, thus eliminating the need to hold the cgroup_mutex. Following this change, task_cgroup_from_root() can be employed in non-sleepable contexts. Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx> --- kernel/cgroup/cgroup.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 1fb7f562289d..bd1692f48be5 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1453,7 +1453,7 @@ static struct cgroup *cset_cgroup_from_root(struct css_set *cset, /* * Return the cgroup for "task" from the given hierarchy. Must be - * called with cgroup_mutex and css_set_lock held. + * called with css_set_lock held. */ struct cgroup *task_cgroup_from_root(struct task_struct *task, struct cgroup_root *root) @@ -1462,7 +1462,8 @@ struct cgroup *task_cgroup_from_root(struct task_struct *task, * No need to lock the task - since we hold css_set_lock the * task can't change groups. */ - return cset_cgroup_from_root(task_css_set(task), root); + lockdep_assert_held(&css_set_lock); + return __cset_cgroup_from_root(task_css_set(task), root); } /* -- 2.30.1 (Apple Git-130)
