On 18.11.2013, at 16:32, Alexander Graf <agraf@xxxxxxx> wrote: > > On 16.11.2013, at 01:55, Paul Mackerras <paulus@xxxxxxxxx> wrote: > >> On Fri, Nov 15, 2013 at 04:35:00PM +0800, Liu Ping Fan wrote: >>> Since kvmppc_hv_find_lock_hpte() is called from both virtmode and >>> realmode, so it can trigger the deadlock. >>> >>> Suppose the following scene: >>> >>> Two physical cpuM, cpuN, two VM instances A, B, each VM has a group of >>> vcpus. >>> >>> If on cpuM, vcpu_A_1 holds bitlock X (HPTE_V_HVLOCK), then is switched >>> out, and on cpuN, vcpu_A_2 try to lock X in realmode, then cpuN will be >>> caught in realmode for a long time. >>> >>> What makes things even worse if the following happens, >>> On cpuM, bitlockX is hold, on cpuN, Y is hold. >>> vcpu_B_2 try to lock Y on cpuM in realmode >>> vcpu_A_2 try to lock X on cpuN in realmode >>> >>> Oops! deadlock happens >>> >>> Signed-off-by: Liu Ping Fan <pingfank@xxxxxxxxxxxxxxxxxx> >> >> Reviewed-by: Paul Mackerras <paulus@xxxxxxxxx> > > Thanks, applied to kvm-ppc-queue. Actually, I've changed my mind and moved the patch to the for-3.13 branch instead. Please make sure to CC kvm@vger on all patches you submit though. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
