[PATCH] KVM_SET_MEMORY_REGION hang in linux 2.6.23.y

[Marko Kohtala <marko.kohtala-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Wait for right amount of tlb flushes. Completed can be larger than
needed and therefore the loop waiting them to match never ends.

Signed-off-by: Marko Kohtala <marko.kohtala-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

---

This solves kernel lockup in KVM_SET_MEMORY_REGION ioctl with Linux
2.6.23.8 and before at kvm-52 start. Not needed in 2.6.24.

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index cd05579..b148aff 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -279,7 +279,8 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
 	 * to complete.
 	 */
 	for (cpu = first_cpu(cpus); cpu != NR_CPUS; cpu = next_cpu(cpu, cpus))
-		smp_call_function_single(cpu, ack_flush, &completed, 1, 0);
+		if (cpu_isset(cpu, cpus))
+			smp_call_function_single(cpu, ack_flush, &completed, 1, 0);
 	while (atomic_read(&completed) != needed) {
 		cpu_relax();
 		barrier();

-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/