[bababobo]

I am new to Linux Mem management, and learning...

Normally when a new page is added to radix tree, address_space nrpages is incremented by 1 as well as the global variable nr_pagecache. Same when a page is removed from the tree.

Then I do not understand why then sum(nr_pages) is much smaller (10 to 20MB) than nr_pagecache (can be x00MB)... I got those numbers from statistics reported in /proc/meminfo,

Can you hint me how to find answer?

Thanks!

[bababobo]

I found the answer: meminfo buffers corresponds to pages for block device file system.

On the other hand, nr_pagecache refers to all files. It includes pages for block device, swap disk and regular file file cache.