From: Yong Zhang Date: Thu, 28 Jul 2011 11:16:00 +0800 Subject: hotplug: Reread hotplug_pcp on pin_current_cpu() retry Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.8/older/patches-4.8.14-rt9.tar.xz When retry happens, it's likely that the task has been migrated to another cpu (except unplug failed), but it still derefernces the original hotplug_pcp per cpu data. Update the pointer to hotplug_pcp in the retry path, so it points to the current cpu. Signed-off-by: Yong Zhang Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20110728031600.GA338@windriver.com Signed-off-by: Thomas Gleixner --- kernel/cpu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -184,9 +184,11 @@ static DEFINE_PER_CPU(struct hotplug_pcp */ void pin_current_cpu(void) { - struct hotplug_pcp *hp = this_cpu_ptr(&hotplug_pcp); + struct hotplug_pcp *hp; retry: + hp = this_cpu_ptr(&hotplug_pcp); + if (!hp->unplug || hp->refcount || preempt_count() > 1 || hp->unplug == current) { hp->refcount++;