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SubjectRe: [PATCH] x86/traps: Weaken context tracking entry assertions

* Andy Lutomirski <luto@kernel.org> wrote:

> We were asserting that we were all the way in CONTEXT_KERNEL when exception
> handlers were called. While having this be true is, I think, a nice goal (or
> maybe a variant in which we assert that we're in CONTEXT_KERNEL or some new IRQ
> context), we're not quite there.
>
> In particular, if an IRQ interrupts the SYSCALL prologue and the IRQ handler in
> turn causes an exception, the exception entry will be called in RCU IRQ mode but
> with CONTEXT_USER.

Hm, so what harm would there be in making IRQ handlers enter CONTEXT_KERNEL?
Would nohz-full break?

I'd rather have a bit more tracking overhead here than lose such useful sanity
checks.

Thanks,

Ingo


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