Function sys_mremap 

pub fn sys_mremap(
    old_addr: u64,
    old_size: u64,
    new_size: u64,
    flags: u64,
) -> Result<u64, SyscallError>

SYS_MREMAP (103): resize an existing mapping.

Current support:

• Shrink in place.
• Grow in place when the following range is free.
• If MREMAP_MAYMOVE is set and growth in place fails, relocate only when the source mapping is still fully lazy (no present pages yet).