About the internal logic of "Memory Cannot be read" error in windows

We occasionally come into this error when running a EXE on windows.

How does OS know if a sp开发者_运维知识库ecific memory can be read or not?

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The CPU walks the page table entries pointed to via the CR3 register - if a matching, valid PTE is not found, this hardware exception will be raised and the NT kernel will turn it into a SEH exception.