This should fix the test from https://reviews.llvm.org/D41128.
How about using calloc instead and benefiting of the "included" zero'd memory feature? That would avoid implementing the touch function.
I won't be able to test anything before Jan. 2nd.
calloc doesn't work because the kernel can use copy-on-write zero pages, see https://willnewton.name/uncategorized/calloc-versus-malloc-and-memset/ for a full explanation. I can use the mentioned memset though and get rid of the touch function :-)