On Thu, Jan 20, 2011 at 11:03:31AM +0800, Xiao Guangrong wrote: > On 01/20/2011 02:13 AM, Marcelo Tosatti wrote: > > On Wed, Jan 19, 2011 at 01:16:23PM +0800, Xiao Guangrong wrote: > >> On 01/12/2011 03:39 PM, Xiao Guangrong wrote: > >>> Fix: > >>> > >>> [ 1001.499596] =================================================== > >>> [ 1001.499599] [ INFO: suspicious rcu_dereference_check() usage. ] > >>> [ 1001.499601] --------------------------------------------------- > >>> [ 1001.499604] include/linux/kvm_host.h:301 invoked rcu_dereference_check() without protection! > >>> ...... > >>> [ 1001.499636] Pid: 6035, comm: qemu-system-x86 Not tainted 2.6.37-rc6+ #62 > >>> [ 1001.499638] Call Trace: > >>> [ 1001.499644] [] lockdep_rcu_dereference+0x9d/0xa5 > >>> [ 1001.499653] [] gfn_to_memslot+0x8d/0xc8 [kvm] > >>> [ 1001.499661] [] gfn_to_hva+0x16/0x3f [kvm] > >>> [ 1001.499669] [] kvm_read_guest_page+0x1e/0x5e [kvm] > >>> [ 1001.499681] [] kvm_read_guest_page_mmu+0x53/0x5e [kvm] > >>> [ 1001.499699] [] load_pdptrs+0x3f/0x9c [kvm] > >>> [ 1001.499705] [] ? vmx_set_cr0+0x507/0x517 [kvm_intel] > >>> [ 1001.499717] [] kvm_arch_vcpu_ioctl_set_sregs+0x1f3/0x3c0 [kvm] > >>> [ 1001.499727] [] kvm_vcpu_ioctl+0x6a5/0xbc5 [kvm] > >>> > >>> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx> > >> > >> Ping ...? > > > > Applied this fix. For the make_all_cpus_request optimization, can you > > show numbers with this new version? Because now there is LOCK# similarly > > to the spinlock. > > Marcelo, > > Sure :-), there is the simply test result of kernbench: > > Before patch: > > real 5m6.493s > user 3m57.847s > sys 9m7.115s > > real 5m1.750s > user 4m0.109s > sys 9m10.192s > > > After patch: > real 5m0.140s > user 3m57.956s > sys 8m58.339s > > real 4m56.314s > user 4m0.303s > sys 8m55.774s Nice. One disadvantageous side effect for the kvm_vcpu_kick path is that it can race with make_all_cpus_request, which is possibly doing unrelated, slower work (IPI'ing other vcpus, waiting for response). Looks ok, but lets wait for more careful reviews before applying. -- 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
