Function mremap_fixed 

pub unsafe fn mremap_fixed(
    old_address: *mut c_void,
    old_size: usize,
    new_size: usize,
    flags: MremapFlags,
    new_address: *mut c_void,
) -> Result<*mut c_void>

mremap(old_address, old_size, new_size, MREMAP_FIXED | flags)—Resize, modify, and/or move a memory mapping to a specific address.

For mremap without moving to a specific address, see mremap. mremap_fixed.

Safety

old_address and new_address must be aligned to the applicable page size, the range of memory starting at old_address and extending for old_size bytes, rounded up to the applicable page size, must be valid to mutate with old_address’s provenance, and the range of memory starting at new_address and extending for new_size bytes, rounded up to the applicable page size, must be valid to mutate with new_address’s provenance.

There must be no Rust references referring to either of those memory regions.

References

• Linux