Not all external callers of cgroup_attach_task() test to
see if the cgroup is still live - the internal callers at
cgroup.c does.
With this test in cgroup_attach_task, we can assure that
no tasks are ever moved to a cgroup that is past its
destruction point and was already marked as dead.
Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
CC: Tejun Heo <tj@xxxxxxxxxx>
CC: Li Zefan <lizefan@xxxxxxxxxx>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
kernel/cgroup.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b61b938..932c318 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1927,6 +1927,9 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
struct cgroup_taskset tset = { };
struct css_set *newcg;
+ if (cgroup_is_removed(cgrp))
+ return -ENODEV;
+
/* @tsk either already exited or can't exit until the end */
if (tsk->flags & PF_EXITING)
return -ESRCH;
--
1.7.7.6
--
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