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

From
Peter Zijlstra <peterz@infradead.org>
Date
2025-06-19 09:45:19
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Reply to
Steven Rostedt, 2025-06-19
On Thu, Jun 19, 2025 at 05:42:31AM -0400, Steven Rostedt wrote:

On June 19, 2025 5:32:26 AM EDT, Peter Zijlstra [off-list ref] wrote:
quoted
On Thu, Jun 19, 2025 at 05:07:10AM -0400, Steven Rostedt wrote:
quoted
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).
We probably can implement this with stacked counters.
I would seriously consider dropping support for anything that can't do
cmpxchg at the width you need.
Thread (79 messages) 79 messages, 6 authors, last reply 2025-06-24
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