Ask HN: Is PostgreSQL memory managment more closer tied to kernel than in MySQL?

I mainly mean things like memory paging (storing data that do not "fit" in memory) - I have vivid memories of reading that PostgreSQL is more close tied to kernel's virtual memory system for managing paging of data than MySQL is which according to what I read implements own paging mechanism that "bypasses" kernel's virtual memory. Is such description accurate? Or is it not accurate at all? Or just partially accurate.