Is my custom field added in page struct guaranteed zero when a page is allocated ?

hi, I add a u64 field in struct page to record corresponding disk sector postion. I will change and read this field when dealing with page cache staff. I want it stays zero unless my code change its value. Will the kernel 's allocating code guarantee that the field is zero when the page is allocated? or Need I add some code to the allocating routine to explicitly fill the field with zero? Regard， Lingyu Zhu