if err != 0 {
		return nil
	}
	return p
}

func sysMapOS(v unsafe.Pointer, n uintptr) {
	// AIX does not allow mapping a range that is already mapped.
	// So, call mprotect to change permissions.
	// Note that sysMap is always called with a non-nil pointer
	// since it transitions a Reserved memory region to Prepared,
	// so mprotect is always possible.
	_, err := mprotect(v, n, _PROT_READ|_PROT_WRITE)
	if err == _ENOMEM {

func sysReserve(v unsafe.Pointer, n uintptr) unsafe.Pointer {
	return sysReserveOS(v, n)
}

// sysMap transitions a memory region from Reserved to Prepared. It ensures the
// memory region can be efficiently transitioned to Ready.
//
// sysStat must be non-nil.
func sysMap(v unsafe.Pointer, n uintptr, sysStat *sysMemStat) {
	sysStat.add(int64(n))
	sysMapOS(v, n)

		}
		// It's possible that after our pruning above, there's nothing new to map.
		if need.size() == 0 {
			continue
		}

		// Map and commit need.
		sysMap(unsafe.Pointer(need.base.addr()), need.size(), p.sysStat)
		sysUsed(unsafe.Pointer(need.base.addr()), need.size(), need.size())
		p.summaryMappedReady += need.size()
	}

	// Update the scavenge index.

		}
		return unsafe.Pointer(ret), 0
	}
	return sysMmap(addr, n, prot, flags, fd, off)
}

func munmap(addr unsafe.Pointer, n uintptr) {
	if _cgo_munmap != nil {
		systemstack(func() { callCgoMunmap(addr, n) })
		return
	}
	sysMunmap(addr, n)
}

// sysMmap calls the mmap system call. It is implemented in assembly.