Hi, I have the same error with a very old machine, a Pentium-M one, (and so no SMP...) trying to compile the source from 4.9.65-3+deb9u2 with a custom config.
The problem is: the "load_new_mm_cr3" function in arch/x86/mm/tlb.c is compiled only when SMP config is defined, but is used in code compiled for no SMP machines (line 160); because of this the "implicit-function-declaration" error. Trying your sugestion, upstream 4.9.75 compile without problems: the tlb.c there has no SMP special code (the header says something about: "formerly SMP-only"...). Cheers, -- David
