Re: [RFC PATCH 1/2] x86/ibpb: Skip IBPB when we switch back to same user process

[Arjan van de Ven]

> This patch tries to address the case when we do switch to init_mm and back.
> Do you still have objections to the approach in this patch
> to save the last active mm before switching to init_mm?

how do you know the last active mm did not go away and started a new process with new content?
(other than taking a reference which has other side effects)