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

[Ingo Molnar <mingo@kernel.org>]

* 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