Re: [PATCHSET SLOP RFC 2/6] selftests/bpf: Add kfunc __arena argument tests

On a pointer to offset 0 being translated as NULL:

offset 0 == NULL is the existing arena representation, not something this
introduces: cast_user already collapses any arena pointer with zero low
32 bits to NULL (the x86 JIT emits test/cmove). So no offset-0 pointer
distinct from NULL exists across the boundary, and the fixup is
consistent with that.

v2: no code change; the flagged comment is reflowed.

Thanks.