diff options
author | David Rientjes <rientjes@google.com> | 2009-04-02 16:57:57 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-02 19:04:57 -0700 |
commit | 6d7b2f5f9e88902b19f91d0c8a7ef58a5455f1a2 (patch) | |
tree | 4ad594fcef55ad95424e58c39e10a723d1dcbe4f | |
parent | db7f47cf4805e30decb0841764b21b7c4000f7dc (diff) | |
download | linux-6d7b2f5f9e88902b19f91d0c8a7ef58a5455f1a2.tar.bz2 |
cpusets: prevent PF_THREAD_BOUND tasks from attaching to non-root cpusets
Kthreads that have the PF_THREAD_BOUND bit set in their flags are bound to a
specific cpu. Thus, their set of allowed cpus shall not change.
This patch prevents such threads from attaching to non-root cpusets. They do
not have mempolicies that restrict them to a subset of system nodes and, since
their cpumask may never change, they cannot use any of the features of
cpusets.
The tasks will forever be a member of the root cpuset and will be returned
when listing the tasks attached to that cpuset.
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | kernel/cpuset.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 2b93b50cbe4b..026faccca869 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1342,19 +1342,22 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont, struct task_struct *tsk) { struct cpuset *cs = cgroup_cs(cont); - int ret = 0; if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)) return -ENOSPC; - if (tsk->flags & PF_THREAD_BOUND) { - mutex_lock(&callback_mutex); - if (!cpumask_equal(&tsk->cpus_allowed, cs->cpus_allowed)) - ret = -EINVAL; - mutex_unlock(&callback_mutex); - } + /* + * Kthreads bound to specific cpus cannot be moved to a new cpuset; we + * cannot change their cpu affinity and isolating such threads by their + * set of allowed nodes is unnecessary. Thus, cpusets are not + * applicable for such threads. This prevents checking for success of + * set_cpus_allowed_ptr() on all attached tasks before cpus_allowed may + * be changed. + */ + if (tsk->flags & PF_THREAD_BOUND) + return -EINVAL; - return ret < 0 ? ret : security_task_setscheduler(tsk, 0, NULL); + return security_task_setscheduler(tsk, 0, NULL); } static void cpuset_attach(struct cgroup_subsys *ss, |