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authorDavid Rientjes <rientjes@google.com>2009-04-02 16:57:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-02 19:04:57 -0700
commit6d7b2f5f9e88902b19f91d0c8a7ef58a5455f1a2 (patch)
tree4ad594fcef55ad95424e58c39e10a723d1dcbe4f /kernel/cpuset.c
parentdb7f47cf4805e30decb0841764b21b7c4000f7dc (diff)
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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>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c19
1 files changed, 11 insertions, 8 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 2b93b50..026facc 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,
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