kpatch-build does not process the calls to module_free() correctly

[euspectre]

I stumbled upon this when processing this patch:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3f7352bf21f8fd7ba3e2fcef9488756f188e12be.

The patch module was prepared without visible errors. But when I tried to load it, the system complained: "Unknown symbol in module". dmesg showed:
[ 622.986678] kpatch_patch: Unknown symbol module_free (err 0)

Looks like, create-diff-object kept the relocation for that call to module_free(). module_free() is not exported to the modules, so, if I understand it correctly, create-diff-object should have created a dynrela for it and omit the original relocation. This is what it does for module_alloc() called from the same function, for example.

The only thing I can see special about module_free() is that it is a "__weak" symbol (and is not redefined on x86).

More details (BTW, thanks to Jessica Yu for making it clearer):
https://www.redhat.com/archives/kpatch/2015-October/msg00012.html

[jpoimboe]

@euspectre Can you check if the patch in #508 fixes the issue?

[euspectre]

Yes, the patch fixed the issue for me. Closing.