Merge branches 'doc.2017.10.20a', 'fixes.2017.10.19a', 'stall.2017.10.09a' and 'torture.2017.10.09a' into HEAD

doc.2017.10.20a: Documentation updates.
fixes.2017.10.19a: Miscellaneous fixes.
stall.2017.10.09a: RCU CPU stall-warning updates.
torture.2017.10.09a: Torture-test updates.