Comment 108 for bug 1674838

I'm now able to produce this pretty reliably with 4.10.0-20.22. My testing shows that the "POWER9: Additional power9 patches" patches are responsible, two of them in particular:

 - mm: introduce page_vma_mapped_walk()
 - mm, ksm: convert write_protect_page() to use page_vma_mapped_walk()

These patches don't appear to be included for any functionality they provide, but rather to make "mm/ksm: handle protnone saved writes when making page write protect" a clean cherry pick instead of a backport. But the backport isn't that difficult, so as far as I can tell we can do away with the other two patches.

I've built 4.10.0-20.22 with just those changes - reverting all three of the above patches then backporting the one which is actually needed - and I'm no longer able to reproduce this bug. Everyone, please give it a try and let me know whether or not you still see problems.

http://people.canonical.com/~sforshee/lp1674838/