This is a note to let you know that I've just added the patch titled
nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off
to the 3.4-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:
nohz-fix-another-inconsistency-between-config_no_hz-n-and-nohz-off.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 0e576acbc1d9600cf2d9b4a141a2554639959d50 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Fri, 29 Nov 2013 12:18:13 +0100
Subject: nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit 0e576acbc1d9600cf2d9b4a141a2554639959d50 upstream.
If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ.
If CONFIG_NO_HZ=y and the nohz functionality is disabled via the
command line option "nohz=off" or not enabled due to missing hardware
support, then tick_nohz_get_sleep_length() returns 0. That happens
because ts->sleep_length is never set in that case.
Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive.
Reported-by: Michal Hocko <mhocko@xxxxxxx>
Reported-by: Borislav Petkov <bp@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Rui Xiang <rui.xiang@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index a12df5abde0b..ea20f7d1ac2c 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -711,8 +711,10 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
return false;
}
- if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
+ if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) {
+ ts->sleep_length = (ktime_t) { .tv64 = NSEC_PER_SEC/HZ };
return false;
+ }
if (need_resched())
return false;
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-3.4/nohz-fix-another-inconsistency-between-config_no_hz-n-and-nohz-off.patch
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