clang-22 -Walloc-size in mm/kfence/kfence_test.c in 6.6 and 6.1

[Nathan Chancellor <nathan@kernel.org>]

Hi kfence folks,

After [1] in clang, I am seeing an instance of this pop up in
mm/kfence/kfence_test.c on linux-6.6.y and linux-6.1.y:

  mm/kfence/kfence_test.c:723:8: error: allocation of insufficient size '0' for type 'char' with size '1' [-Werror,-Walloc-size]
    723 |         buf = krealloc(buf, 0, GFP_KERNEL); /* Free. */
        |               ^

I do not see this in linux-6.12.y or newer but I wonder if that is just
because the memory allocation profiling adds some indirection that makes
it harder for clang to perform this analysis?

Should this warning just be silenced for this translation unit or is
there some other fix that could be done here?

[1]: https://github.com/llvm/llvm-project/commit/6dc188d4eb15cbe9bdece3d940f03d93b926328c

Cheers,
Nathan