This is a note to let you know that I've just added the patch titled
CPU hotplug, cpusets, suspend: Don't touch cpusets during suspend/resume
to the 3.2-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:
cpu-hotplug-cpusets-suspend-don-t-touch-cpusets-during-suspend-resume.patch
and it can be found in the queue-3.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 8f2f748b0656257153bcf0941df8d6060acc5ca6 Mon Sep 17 00:00:00 2001
From: "Srivatsa S. Bhat" <[email protected]>
Date: Thu, 23 Feb 2012 15:27:15 +0530
Subject: CPU hotplug, cpusets, suspend: Don't touch cpusets during
suspend/resume
From: "Srivatsa S. Bhat" <[email protected]>
commit 8f2f748b0656257153bcf0941df8d6060acc5ca6 upstream.
Currently, during CPU hotplug, the cpuset callbacks modify the cpusets
to reflect the state of the system, and this handling is asymmetric.
That is, upon CPU offline, that CPU is removed from all cpusets. However
when it comes back online, it is put back only to the root cpuset.
This gives rise to a significant problem during suspend/resume. During
suspend, we offline all non-boot cpus and during resume we online them back.
Which means, after a resume, all cpusets (except the root cpuset) will be
restricted to just one single CPU (the boot cpu). But the whole point of
suspend/resume is to restore the system to a state which is as close as
possible to how it was before suspend.
So to fix this, don't touch cpusets during suspend/resume. That is, modify
the cpuset-related CPU hotplug callback to just ignore CPU hotplug when it
is initiated as part of the suspend/resume sequence.
Reported-by: Prashanth Nageshappa <[email protected]>
Signed-off-by: Srivatsa S. Bhat <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Andrew Morton <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Zijlstra <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/sched.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8001,7 +8001,7 @@ int __init sched_create_sysfs_power_savi
static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
- switch (action & ~CPU_TASKS_FROZEN) {
+ switch (action) {
case CPU_ONLINE:
case CPU_DOWN_FAILED:
cpuset_update_active_cpus();
@@ -8014,7 +8014,7 @@ static int cpuset_cpu_active(struct noti
static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long
action,
void *hcpu)
{
- switch (action & ~CPU_TASKS_FROZEN) {
+ switch (action) {
case CPU_DOWN_PREPARE:
cpuset_update_active_cpus();
return NOTIFY_OK;
Patches currently in stable-queue which might be from
[email protected] are
queue-3.2/cpu-hotplug-cpusets-suspend-don-t-touch-cpusets-during-suspend-resume.patch
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