Page faults occurs when the process tries to access a memory that isn’t backed by a physical page kernel raises a fault which loads a page. It happens on first access, stack expansion, COW, swap and much more. However it comes with a cost. 

In this episode of the backend engineering show I dissect the need and the cost page faults in the kernel. 

• 0:00 Intro 
• 4:00 Virtual memory
• • Abstraction of physical memory
  • Memory sharing
  • Allow more processes to run , unused go to disk
  • Numa, kernel can place memory near the cpu
• 12:00 VMA areas
• • Text/code 
  • Data 
  • BSS
  • Heap
  • Stack
• 19:50 Kernel mode
• 25:30 What is a Page fault?
• 30:30 First access page fault
• 33:00 Stack Expansion page fault
• 34:30 CoW page fault
• 38:00 Swap page fault
• 39:39 File backed page fault
• 40:29 Permission page fault 
• 45:30 Summary