This is a note to let you know that I've just added the patch titled
sched: Fix RLIMIT_RTTIME when PI-boosting to RT
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-fix-rlimit_rttime-when-pi-boosting-to-rt.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 746db9443ea57fd9c059f62c4bfbf41cf224fe13 Mon Sep 17 00:00:00 2001
From: Brian Silverman <brian@xxxxxxxxxxxxxxxx>
Date: Wed, 18 Feb 2015 16:23:56 -0800
Subject: sched: Fix RLIMIT_RTTIME when PI-boosting to RT
From: Brian Silverman <brian@xxxxxxxxxxxxxxxx>
commit 746db9443ea57fd9c059f62c4bfbf41cf224fe13 upstream.
When non-realtime tasks get priority-inheritance boosted to a realtime
scheduling class, RLIMIT_RTTIME starts to apply to them. However, the
counter used for checking this (the same one used for SCHED_RR
timeslices) was not getting reset. This meant that tasks running with a
non-realtime scheduling class which are repeatedly boosted to a realtime
one, but never block while they are running realtime, eventually hit the
timeout without ever running for a time over the limit. This patch
resets the realtime timeslice counter when un-PI-boosting from an RT to
a non-RT scheduling class.
I have some test code with two threads and a shared PTHREAD_PRIO_INHERIT
mutex which induces priority boosting and spins while boosted that gets
killed by a SIGXCPU on non-fixed kernels but doesn't with this patch
applied. It happens much faster with a CONFIG_PREEMPT_RT kernel, and
does happen eventually with PREEMPT_VOLUNTARY kernels.
Signed-off-by: Brian Silverman <brian@xxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: austin@xxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1424305436-6716-1-git-send-email-brian@xxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sched/core.c | 2 ++
1 file changed, 2 insertions(+)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2980,6 +2980,8 @@ void rt_mutex_setprio(struct task_struct
} else {
if (dl_prio(oldprio))
p->dl.dl_boosted = 0;
+ if (rt_prio(oldprio))
+ p->rt.timeout = 0;
p->sched_class = &fair_sched_class;
}
Patches currently in stable-queue which might be from brian@xxxxxxxxxxxxxxxx are
queue-3.14/sched-fix-rlimit_rttime-when-pi-boosting-to-rt.patch
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