sched: Fix switch_from_fair()

When a task is taken out of the fair class we must ensure the vruntime
is properly normalized because when we put it back in it will assume
to be normalized.

The case that goes wrong is when changing away from the fair class
while sleeping. Sleeping tasks have non-normalized vruntime in order
to make sleeper-fairness work. So treat the switch away from fair as a
wakeup and preserve the relative vruntime.

Also update sysrq-n to call the ->switch_{to,from} methods.

Reported-by: Onkalo Samu <samu.p.onkalo@nokia.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 5 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index af6e15fbfb78..0542774914d4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1084,12 +1084,10 @@ struct sched_class {
         void (*task_tick) (struct rq *rq, struct task_struct *p, int queued);
         void (*task_fork) (struct task_struct *p);
 
-        void (*switched_from) (struct rq *this_rq, struct task_struct *task,
-                               int running);
-        void (*switched_to) (struct rq *this_rq, struct task_struct *task,
-                             int running);
+        void (*switched_from) (struct rq *this_rq, struct task_struct *task);
+        void (*switched_to) (struct rq *this_rq, struct task_struct *task);
         void (*prio_changed) (struct rq *this_rq, struct task_struct *task,
-                             int oldprio, int running);
+                             int oldprio);
 
         unsigned int (*get_rr_interval) (struct rq *rq,
                                          struct task_struct *task);