From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: [patch 22/60] KVM: Fix hang on uniprocessor Date: Wed, 12 Dec 2007 22:52:04 -0800 Message-ID: <20071213065204.GW6867@kroah.com> References: <20071213064518.328162328@mini.kroah.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Justin Forbes , Zwane Mwaikambo , Theodore Ts'o , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, kvm-devel@lists.sourceforge.net, Marko Kohtala , Avi Kivity To: linux-kernel@vger.kernel.org, stable@kernel.org Return-path: Content-Disposition: inline; filename="kvm-fix-hang-on-uniprocessor.patch" In-Reply-To: <20071213065039.GA6867@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 2.6.23-stable review patch. If anyone has any objections, please let us know. ------------------ From: Marko Kohtala This is not in mainline, as it was fixed differently in that tree. first_cpu(cpus) returns the only CPU when NR_CPUS is 1 regardless of the cpus mask. Therefore we avoid a kernel hang in KVM_SET_MEMORY_REGION ioctl on uniprocessor by not entering the loop at all. Signed-off-by: Marko Kohtala Signed-off-by: Avi Kivity Signed-off-by: Greg Kroah-Hartman --- drivers/kvm/kvm_main.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/drivers/kvm/kvm_main.c +++ b/drivers/kvm/kvm_main.c @@ -273,6 +273,11 @@ void kvm_flush_remote_tlbs(struct kvm *k } } + /* Uniprocessor kernel does not respect cpus in first_cpu. So + * do not go there if we have nothing to do. */ + if (cpus_empty(cpus)) + return; + /* * We really want smp_call_function_mask() here. But that's not * available, so ipi all cpus in parallel and wait for them --