The structure of that file can be found at https://www.kernel.org/doc/Documentation/vm/pagemap.txt

Seems you have to unpack fixed length data.
Maybe this Pack/Unpack Tutorial (aka How the System Stores Data) will be of some interest for you.

In reply to Re: How to parse /proc/pid/pagemap and create an appropriate data structure by rizzo
in thread How to parse /proc/pid/pagemap and create an appropriate data structure by PerlNew99

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