filemap: update offset check in filemap_fault()

filemap: update offset check in filemap_fault()

With THP, current check of offset:

    VM_BUG_ON_PAGE(page->index != offset, page);

is no longer accurate. Update it to:

    VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Song Liu <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>