MariaDB RAM usage does not reflect configuration
MariaDB's memory usage grows over time. It stops growing when certain configurable settings are hit. In practice, it mostly stops growing long before the 'theoretical' limit is hit.
The buffer_pool is allocated only in RAM.  It is the main memory user that grows over time, stopping when it hits innodb_buffer_pool_size.
Since the buffer_pool is a &quot;cache&quot;, the data can be much bigger than the buffer_pool; the downside is the need to do more I/O to pull &quot;blocks&quot; of data (or indexes) into the cache, bumping out other blocks.
If all of the activity is concentrated on a subset of the data (eg, &quot;recent&quot; items), then the buffer_pool grows until &quot;big enough&quot; and may not actually expand to innodb_buffer_pool_size.  I/O activity will be low.
If the buffer_pool is bigger than all the InnoDB data and indexes you have, it will grow to about that size and then simply stay at that size.
The innodb_buffer_pool_size should not be so large that you run out of RAM.  When that happens, swapping occurs.  If there is no swap space, then the process is killed.