sched: fix, always create kernel threads with normal priority
Ensure that the kernel threads are created with the usual nice level
and affinity even if kthreadd's properties were changed from the
default by root.
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/kthread.c b/kernel/kthread.c
index dcfe724..0ac8878 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -15,6 +15,8 @@
#include <linux/mutex.h>
#include <asm/semaphore.h>
+#define KTHREAD_NICE_LEVEL (-5)
+
static DEFINE_SPINLOCK(kthread_create_lock);
static LIST_HEAD(kthread_create_list);
struct task_struct *kthreadd_task;
@@ -94,10 +96,18 @@
if (pid < 0) {
create->result = ERR_PTR(pid);
} else {
+ struct sched_param param = { .sched_priority = 0 };
wait_for_completion(&create->started);
read_lock(&tasklist_lock);
create->result = find_task_by_pid(pid);
read_unlock(&tasklist_lock);
+ /*
+ * root may have changed our (kthreadd's) priority or CPU mask.
+ * The kernel thread should not inherit these properties.
+ */
+ sched_setscheduler(create->result, SCHED_NORMAL, ¶m);
+ set_user_nice(create->result, KTHREAD_NICE_LEVEL);
+ set_cpus_allowed(create->result, CPU_MASK_ALL);
}
complete(&create->done);
}
@@ -221,7 +231,7 @@
/* Setup a clean context for our children to inherit. */
set_task_comm(tsk, "kthreadd");
ignore_signals(tsk);
- set_user_nice(tsk, -5);
+ set_user_nice(tsk, KTHREAD_NICE_LEVEL);
set_cpus_allowed(tsk, CPU_MASK_ALL);
current->flags |= PF_NOFREEZE;