Re: kprobes broken since 0d00449c7a28 ("x86: Replace ist_enter() with nmi_enter()")

[Peter Zijlstra]

On Fri, Jan 29, 2021 at 04:24:54PM -0500, Steven Rostedt wrote:
> Specifically, kprobe and ftrace callbacks may have this:
> 
> 	if (in_nmi())
> 		return;
> 
> 	raw_spin_lock_irqsave(&lock, flags);
> 	[..]
> 	raw_spin_unlock_irqrestore(&lock, flags);
> 
> Which is totally fine to have,

Why? There's a distinct lack of explaining here.

Note that we ripped out all such dodgy locking from kretprobes.