> Am 20.11.2013 um 03:42 schrieb Liu ping fan <kernelfans@xxxxxxxxx>: > >> On Tue, Nov 19, 2013 at 6:39 PM, Alexander Graf <agraf@xxxxxxx> wrote: >> >>> On 19.11.2013, at 07:12, Liu Ping Fan <kernelfans@xxxxxxxxx> 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> >> >> Any particular reason for the resend? The patch is already applied, no? > Oh, seems that I misunderstood your meaning. You said "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". So > I think it is necessary to resend with cc kvm@vger Oh. I meant "for next time" :). But now that it happened for this patch already it's even better. Thanks a lot! Alex > > Regards, > Pingfan -- 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
