# Re: \[PATCH v10 07/14\] unwind\_user/deferred: Make unwind deferral requests NMI-safe

- From: Peter Zijlstra \<peterz@infradead.org\>
- Date: 2025-06-19 09:32:40 
- List: linux-trace-kernel
- Page: https://ratatoskr.run/linux-trace-kernel/2025/06/3098774
- Thread: https://ratatoskr.run/linux-trace-kernel/2025/06/3086227/t.md

```text
On Thu, Jun 19, 2025 at 05:07:10AM -0400, Steven Rostedt wrote:

> Does #DB make in_nmi() true? If that's the case then we do need to handle that.

Yes: #DF, #MC, #BP (int3), #DB and NMI all have in_nmi() true.

Ignoring #DF because that's mostly game over, you can get them all
nested for up to 4 (you're well aware of the normal NMI recursion
crap).

Then there is the SEV #VC stuff, which is also NMI like. So if you're a
CoCo-nut, you can perhaps get it up to 5.
```