Commit 4293f20c authored Mar 07, 2012 by Linus Torvalds

Revert "CPU hotplug, cpusets, suspend: Don't touch cpusets during suspend/resume"



This reverts commit 8f2f748b.

It causes some odd regression that we have not figured out, and it's too
late in the -rc series to try to figure it out now.

As reported by Konstantin Khlebnikov, it causes consistent hangs on his
laptop (Thinkpad x220: 2x cores + HT).  They can be avoided by adding
calls to "rebuild_sched_domains();" in cpuset_cpu_[in]active() for the
CPU_{ONLINE/DOWN_FAILED/DOWN_PREPARE}_FROZEN cases, but it's not at all
clear why, and it makes no sense.

Konstantin's config doesn't even have CONFIG_CPUSETS enabled, just to
make things even more interesting.  So it's not the cpusets, it's just
the scheduling domains.

So until this is understood, revert.

Bisected-reported-and-tested-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent dac12d1f

kernel/sched/core.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -6728,7 +6728,7 @@ int __init sched_create_sysfs_power_savings_entries(struct device *dev)
		static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
		void *hcpu)
		{
		switch (action) {
		switch (action & ~CPU_TASKS_FROZEN) {
		case CPU_ONLINE:
		case CPU_DOWN_FAILED:
		cpuset_update_active_cpus();
		@@ -6741,7 +6741,7 @@ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
		static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
		void *hcpu)
		{
		switch (action) {
		switch (action & ~CPU_TASKS_FROZEN) {
		case CPU_DOWN_PREPARE:
		cpuset_update_active_cpus();
		return NOTIFY_OK;

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