* Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Wed, Jan 03, 2018 at 12:46:00AM -0800, Benjamin Gilbert wrote: > > [resending with less web] > > (adding lkml and x86 developers) > > > Hi all, > > > > In our regression tests on kernel 4.14.11, we're occasionally seeing a run > > of "bad pmd" messages during boot, followed by a "BUG: unable to handle > > kernel paging request". This happens on no more than a couple percent of > > boots, but we've seen it on AWS HVM, GCE, Oracle Cloud VMs, and local QEMU > > instances. It always happens immediately after "Loading compiled-in X.509 > > certificates". I can't reproduce it on 4.14.10, nor, so far, on 4.14.11 > > with pti=off. Here's a sample backtrace: A few other things to check: first please test the latest WIP.x86/pti branch which has a couple of fixes. In a -stable kernel tree you should be able to do: git pull --no-tags git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.x86/pti in particular this recent fix from a couple of hours ago might make a difference: 52994c256df3: x86/pti: Make sure the user/kernel PTEs match Note that this commit: 694d99d40972: x86/cpu, x86/pti: Do not enable PTI on AMD processors disables PTI on AMD CPUs - so if you'd like to test it more broadly on all CPUs then you'll need to add "pti=on" to your boot commandline. Thanks, Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
