Man page 9 : replace_page_cache_page

replace_page_cache_page - replace a pagecache page with a new one

int replace_page_cache_page(struct page *  old , struct page *  new , gfp_t  gfp_mask );

old
    page to be replaced

new
    page to replace with

gfp_mask
    allocation mode

This function replaces a page in the pagecache with a new one. On success it acquires the pagecache reference for the new page and drops it for the old page. Both the old and new pages must be locked. This function does not add the new page to the LRU, the caller must do that.

The remove + add is atomic. The only way this function can fail is memory allocation failure.