sched: do not normalize kernel threads via SysRq-N
do not normalize kernel threads via SysRq-N: the migration threads,
softlockup threads, etc. might be essential for the system to
function properly. So only zap user tasks.
pointed out by Andi Kleen.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index fc61b1f..791dd08 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -365,15 +365,6 @@
#endif
}
-static inline int is_migration_thread(struct task_struct *p, struct rq *rq)
-{
-#ifdef CONFIG_SMP
- return p == rq->migration_thread;
-#else
- return 0;
-#endif
-}
-
/*
* Update the per-runqueue clock, as finegrained as the platform can give
* us, but without assuming monotonicity, etc.:
@@ -6563,6 +6554,12 @@
read_lock_irq(&tasklist_lock);
do_each_thread(g, p) {
+ /*
+ * Only normalize user tasks:
+ */
+ if (!p->mm)
+ continue;
+
p->se.exec_start = 0;
#ifdef CONFIG_SCHEDSTATS
p->se.wait_start = 0;
@@ -6584,8 +6581,7 @@
spin_lock_irqsave(&p->pi_lock, flags);
rq = __task_rq_lock(p);
- if (!is_migration_thread(p, rq))
- normalize_task(rq, p);
+ normalize_task(rq, p);
__task_rq_unlock(rq);
spin_unlock_irqrestore(&p->pi_lock, flags);