diff options
| author | Mike Galbraith <mgalbraith@suse.de> | 2012-04-21 09:13:46 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2012-04-23 11:03:51 -0700 |
| commit | c4c27fbdda4e8ba87806c415b6d15266b07bce4b (patch) | |
| tree | e532518e0942a2562642744103eb64554c8abbda /kernel/cgroup.c | |
| parent | 86f82d561864e902c70282b6f17cf590c0f34691 (diff) | |
cgroups: disallow attaching kthreadd or PF_THREAD_BOUND threads
Allowing kthreadd to be moved to a non-root group makes no sense, it being
a global resource, and needlessly leads unsuspecting users toward trouble.
1. An RT workqueue worker thread spawned in a task group with no rt_runtime
allocated is not schedulable. Simple user error, but harmful to the box.
2. A worker thread which acquires PF_THREAD_BOUND can never leave a cpuset,
rendering the cpuset immortal.
Save the user some unexpected trouble, just say no.
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index b2f203f25ec..ad8eae5bb80 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -60,6 +60,7 @@ #include <linux/eventfd.h> #include <linux/poll.h> #include <linux/flex_array.h> /* used in cgroup_attach_proc */ +#include <linux/kthread.h> #include <linux/atomic.h> @@ -2225,6 +2226,18 @@ retry_find_task: if (threadgroup) tsk = tsk->group_leader; + + /* + * Workqueue threads may acquire PF_THREAD_BOUND and become + * trapped in a cpuset, or RT worker may be born in a cgroup + * with no rt_runtime allocated. Just say no. + */ + if (tsk == kthreadd_task || (tsk->flags & PF_THREAD_BOUND)) { + ret = -EINVAL; + rcu_read_unlock(); + goto out_unlock_cgroup; + } + get_task_struct(tsk); rcu_read_unlock(); |