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You could still make an argument for that if you squint hard enough. The virtual memory is still reserved, and a transition to kernel mode still has user space mapped, and the kernel's view of memory as well.



Thanks for clarifying! Is whatever the kernel does now in transition to user space expensive because it's somehow proportional to the amount of actual memory that the kernel is using or has reserved?


No, it's still more or less a O(1) operation, it's just expensive to fully flush TLBs.




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