diff options
Diffstat (limited to 'include/linux/cgroup.h')
| -rw-r--r-- | include/linux/cgroup.h | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index ca51b2c15bcc..8937d48a5389 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -485,7 +485,7 @@ static inline struct cgroup_subsys_state *task_css(struct task_struct *task, * * Find the css for the (@task, @subsys_id) combination, increment a * reference on and return it. This function is guaranteed to return a - * valid css. + * valid css. The returned css may already have been offlined. */ static inline struct cgroup_subsys_state * task_get_css(struct task_struct *task, int subsys_id) @@ -495,7 +495,13 @@ task_get_css(struct task_struct *task, int subsys_id) rcu_read_lock(); while (true) { css = task_css(task, subsys_id); - if (likely(css_tryget_online(css))) + /* + * Can't use css_tryget_online() here. A task which has + * PF_EXITING set may stay associated with an offline css. + * If such task calls this function, css_tryget_online() + * will keep failing. + */ + if (likely(css_tryget(css))) break; cpu_relax(); } |