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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2012-02-23 04:57:15 -0500
committerIngo Molnar <mingo@elte.hu>2012-02-27 05:38:13 -0500
commit8f2f748b0656257153bcf0941df8d6060acc5ca6 (patch)
tree960e37a40212b88dd25be216addf7381c87c84fe /kernel/sched
parent8c79a045fd590a26e81e75f5d8d4ec5c7d23e565 (diff)
CPU hotplug, cpusets, suspend: Don't touch cpusets during suspend/resume
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 <prashanth@linux.vnet.ibm.com> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/4F460D7B.1020703@linux.vnet.ibm.com Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b342f57879e6..33a0676ea744 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6728,7 +6728,7 @@ int __init sched_create_sysfs_power_savings_entries(struct device *dev)
6728static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, 6728static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
6729 void *hcpu) 6729 void *hcpu)
6730{ 6730{
6731 switch (action & ~CPU_TASKS_FROZEN) { 6731 switch (action) {
6732 case CPU_ONLINE: 6732 case CPU_ONLINE:
6733 case CPU_DOWN_FAILED: 6733 case CPU_DOWN_FAILED:
6734 cpuset_update_active_cpus(); 6734 cpuset_update_active_cpus();
@@ -6741,7 +6741,7 @@ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
6741static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, 6741static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
6742 void *hcpu) 6742 void *hcpu)
6743{ 6743{
6744 switch (action & ~CPU_TASKS_FROZEN) { 6744 switch (action) {
6745 case CPU_DOWN_PREPARE: 6745 case CPU_DOWN_PREPARE:
6746 cpuset_update_active_cpus(); 6746 cpuset_update_active_cpus();
6747 return NOTIFY_OK; 6747 return NOTIFY_OK;