Patchwork [22/75] sched: Fix the broken sched_rr_get_interval()

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Submitter Luis Henriques
Date Aug. 14, 2013, 10:36 a.m.
Message ID <>
Download mbox | patch
Permalink /patch/267101/
State New
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Luis Henriques - Aug. 14, 2013, 10:36 a.m. -stable review patch.  If anyone has any objections, please let me know.


From: Zhu Yanhai <>

commit a59f4e079d19464eebb9b06513a1d4f55fdae5ba upstream.

The caller of sched_sliced() should pass se.cfs_rq and se as the
arguments, however in sched_rr_get_interval() we gave it
rq.cfs_rq and se, which made the following computation obviously

The change was introduced by commit:

  77034937dc45 sched: fix crash in sys_sched_rr_get_interval()

... 5 years ago, while it had been the correct 'cfs_rq_of' before
the commit. The change seems to be irrelevant to the commit
msg, which was to return a 0 timeslice for tasks that are on an
idle runqueue. So I believe that was just a plain typo.

Signed-off-by: Zhu Yanhai <>
Cc: Peter Zijlstra <>
Cc: Paul Turner <>
Cc: Thomas Gleixner <>
Cc: Steven Rostedt <>
Cc: Andrew Morton <>
Cc: Linus Torvalds <>
[ Since this is an ABI and an old bug, we'll test this via a
  slow upstream route, to hopefully discover any app breakage. ]
Signed-off-by: Ingo Molnar <>
Cc: Li Zefan <>
Acked-by: Ingo Molnar <>
Signed-off-by: Luis Henriques <>
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c099cc6..eb12b9e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5250,7 +5250,7 @@  static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task
 	 * idle runqueue:
 	if (rq->cfs.load.weight)
-		rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
+		rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se));
 	return rr_interval;