From 51a96c77815e7f139892a6e9c8275a50e9baebdf Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 19 Nov 2010 20:37:53 +0100 Subject: cpu: Remove incorrect BUG_ON Oleg mentioned that there is no actual guarantee the dying cpu's migration thread is actually finished running when we get there, so replace the BUG_ON() with a spinloop waiting for it. Reported-by: Oleg Nesterov Signed-off-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/cpu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel/cpu.c') diff --git a/kernel/cpu.c b/kernel/cpu.c index 3945066fc01..cb7a1efa9c2 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -249,8 +249,11 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) * The migration_call() CPU_DYING callback will have removed all * runnable tasks from the cpu, there's only the idle task left now * that the migration thread is done doing the stop_machine thing. + * + * Wait for the stop thread to go away. */ - BUG_ON(!idle_cpu(cpu)); + while (!idle_cpu(cpu)) + cpu_relax(); /* This actually kills the CPU. */ __cpu_die(cpu); -- cgit v1.2.3-18-g5258