Comment 97 for bug 1674838

@Joseph Salisbury,

Hi.

It looks as if the Ubuntu kernel source has diverged from stable in a significant way. In particular,
as has already been noted, on 3/10/2017, Canonical cherry-picked several patches from 4.11-pre, apparently relating to:

http://bugs.launchpad.net/bugs/1671613

Somewhere in there, I suspect, is the underlying cause of the present BUG.

You already tried overlaying an essential fix-up, d75450ff40df0199bf13dfb19f435519ff947138, as suggested in comment #52, and that did appear to improve stability, but not completely resolve the issue for myself and others.

Looking at mainline, I see a rather large number of memory memory management-related patches from Kirill A. Shutemov and others that follow ace71a19cec5eb430207c3269d8a2683f0574306 "mm: introduce page_vma_mapped_walk()" from 2/24/2017. It could be that adding one or more of those patches would stabilize the backported series relating to http://bugs.launchpad.net/bugs/1671613.

The reason for this note is to observe that the absence of the present BUG in 4.10.x stable may well be due to the absence of the Canonical backported patches, rather than due to some additive fix.

Reverting the http://bugs.launchpad.net/bugs/1671613 patch series might be another path to isolating the source of the BUG.