why the count nr_file_pages is not equal to nr_inactive_file + nr_active_file ?

[Xishi Qiu]

I find the count nr_file_pages is not equal to nr_inactive_file + nr_active_file.
There are 8 cpus, 2 zones in my system.

I think may be the pagevec trigger the problem, but PAGEVEC_SIZE is only 14.
Does anyone know the reason?

Thanks,
Xishi Qiu

root@hi3650:/ # cat /proc/vmstat 
nr_free_pages 54192
nr_inactive_anon 39830
nr_active_anon 28794
nr_inactive_file 432444
nr_active_file 20659
nr_unevictable 2363
nr_mlock 0
nr_anon_pages 65249
nr_mapped 19742
nr_file_pages 462723
nr_dirty 20
nr_writeback 0
...


nr_inactive_file 432444
nr_active_file 20659
total is 453103

nr_file_pages 462723