Re: [tip: objtool/core] jump_label, x86: Allow short NOPs

[Matthew Wilcox]

On Tue, Jun 29, 2021 at 09:01:25PM +0100, Matthew Wilcox wrote:
> So this got merged without the corresponding Kbuild update being merged,
> and my kernel failed to boot.  Bisect got as far as
> 
> $ git bisect good
> Bisecting: 4 revisions left to test after this (roughly 2 steps)
> [ab3257042c26d0cd44793c741e2f89bf38b21fe8] jump_label, x86: Allow short NOPs
> 
> before my sluggish memory remembered this thread from six weeks ago.
> 
> So if anybody else hits this, do a make clean.

Actually, this is a different bug with the same symptom.

Applying the patch from Peter, and running it:

$ ./.build_test_kernel-x86_64/tools/objtool/objtool check -abdJsuld .build_test_kernel-x86_64/vmlinux.o
nr_sections: 15446
section_bits: 13
nr_symbols: 116448
symbol_bits: 16
max_reloc: 8031700
tot_reloc: 12477754
reloc_bits: 19
nr_insns: 2523443
.build_test_kernel-x86_64/vmlinux.o: warning: objtool: want_init_on_free()+0x0: jump-label unpatched

This is against a freshly built kernel -- i removed the build directory,
copied in a .config file and built a fresh kernel.