On Mon, Apr 20, 2015 at 01:27:58PM -0700, Andy Lutomirski wrote: > On Mon, Apr 20, 2015 at 9:59 AM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > > > > > On 17/04/2015 22:18, Marcelo Tosatti wrote: > >> The bug which this is fixing is very rare, have no memory of a report. > >> > >> In fact, its even difficult to create a synthetic reproducer. > > > > But then why was the task migration notifier even in Jeremy's original > > code for Xen? Was it supposed to work even on non-synchronized TSC? > > > > If that's the case, then it could be reverted indeed; but then why did > > you commit this patch to 4.1? Did you think of something that would > > cause the seqcount-like protocol to fail, and that turned out not to be > > the case later? I was only following the mailing list sparsely in March. > > I don't think anyone ever tried that hard to test this stuff. There > was an infinte loop that Firefox was triggering as a KVM guest > somewhat reliably until a couple months ago in the same vdso code. :( https://bugzilla.redhat.com/show_bug.cgi?id=1174664 --- Comment #5 from Juan Quintela <quintela@xxxxxxxxxx> --- Another round # dmesg | grep msr [ 0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00 [ 0.000000] kvm-clock: cpu 0, msr 1:1ffd8001, primary cpu clock [ 0.000000] kvm-stealtime: cpu 0, msr 11fc0d100 [ 0.041174] kvm-clock: cpu 1, msr 1:1ffd8041, secondary cpu clock [ 0.053011] kvm-stealtime: cpu 1, msr 11fc8d100 After start: [root@trasno yum.repos.d]# virsh qemu-monitor-command --hmp browser 'xp /8x 0x1ffd8000' 000000001ffd8000: 0x3b401060 0xfffc7f4b 0x3b42d040 0xfffc7f4b 000000001ffd8010: 0x3b42d460 0xfffc7f4b 0x3b42d4c0 0xfffc7f4b [root@trasno yum.repos.d]# virsh qemu-monitor-command --hmp browser 'xp /8x 0x1ffd8040' 000000001ffd8040: 0x3b42d700 0xfffc7f4b 0x3b42d760 0xfffc7f4b 000000001ffd8050: 0x3b42d7c0 0xfffc7f4b 0x3b42d820 0xfffc7f4b When firefox hangs [root@trasno yum.repos.d]# virsh qemu-monitor-command --hmp browser 'xp /8x 0x1ffd8000' 000000001ffd8000: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 000000001ffd8010: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a [root@trasno yum.repos.d]# virsh qemu-monitor-command --hmp browser 'xp /8x 0x1ffd8040' 000000001ffd8040: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 000000001ffd8050: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a -- 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
