On Thu, Apr 23, 2015 at 11:13:23AM +0200, Paolo Bonzini wrote: > > > On 22/04/2015 23:21, Marcelo Tosatti wrote: > > 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 > > That was the missing volatile in an asm. Older compilers didn't catch > it. :( How do you know that? It looks like memory corruption (look at the pattern at the end). -- 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
