sched: Fix hotplug vs. set_cpus_allowed_ptr()

Lai found that: WARNING: CPU: 1 PID: 13 at arch/x86/kernel/smp.c:124 native_smp_send_reschedule+0x2d/0x4b() ... migration_cpu_stop+0x1d/0x22 was caused by set_cpus_allowed_ptr() assuming that cpu_active_mask is always a sub-set of cpu_online_mask. This isn't true since 5fbd036 ("sched: Cleanup cpu_active madness"). So set active and online at the same time to avoid this particular problem. Fixes: 5fbd036 ("sched: Cleanup cpu_active madness") Signed-off-by: Lai Jiangshan <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Gautham R. Shenoy <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Michael wang <[email protected]> Cc: Paul Gortmaker <[email protected]> Cc: Rafael J. Wysocki <[email protected]> Cc: Srivatsa S. Bhat <[email protected]> Cc: Toshi Kani <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
open-power · May 22, 2014 · 6acbfb9 · 6acbfb9
1 parent 4dac0b6
commit 6acbfb9
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Showing 2 changed files with 4 additions and 3 deletions.
diff --git a/kernel/cpu.c b/kernel/cpu.c
@@ -726,10 +726,12 @@ void set_cpu_present(unsigned int cpu, bool present)
 
 void set_cpu_online(unsigned int cpu, bool online)
 {
-	if (online)
+	if (online) {
 		cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
-	else
+		cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
+	} else {
 		cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
+	}
 }
 
 void set_cpu_active(unsigned int cpu, bool active)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
@@ -5076,7 +5076,6 @@ static int sched_cpu_active(struct notifier_block *nfb,
 				      unsigned long action, void *hcpu)
 {
 	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_STARTING:
 	case CPU_DOWN_FAILED:
 		set_cpu_active((long)hcpu, true);
 		return NOTIFY_OK;