I also have this problem, which I reported as a new bug 1886775 which is probably just a duplicate of this bug. Same issue, -40 dies with NFS with similar stack trace and similar timing, -39 is fine, and multiple hardware has the identical issues.
I also have this problem, which I reported as a new bug 1886775 which is probably just a duplicate of this bug. Same issue, -40 dies with NFS with similar stack trace and similar timing, -39 is fine, and multiple hardware has the identical issues.