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Date: Tue, 3 Mar 2026 17:00:50 +0100
From: Christoph Hellwig <hch@lst.de>
To: Peter Zijlstra <peterz@infradead.org>
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Subject: Re: [PATCH 01/25] xor: assert that xor_blocks is not called from
 interrupt context
Message-ID: <20260303160050.GB7021@lst.de>
References: <20260226151106.144735-1-hch@lst.de> <20260226151106.144735-2-hch@lst.de> <20260227142455.GG1282955@noisy.programming.kicks-ass.net>
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On Fri, Feb 27, 2026 at 03:24:55PM +0100, Peter Zijlstra wrote:
> >  	unsigned long *p1, *p2, *p3, *p4;
> >  
> > +	WARN_ON_ONCE(in_interrupt());
> 
> Your changelog makes it sound like you want:
> 
> 	WARN_ON_ONCE(!in_task());
> 
> But perhaps something like so:
> 
> 	lockdep_assert_preempt_enabled();
> 
> Would do? That ensures we are in preemptible context, which is much the
> same. That also ensures the cost of this assertion is only paid on debug
> kernels.

No idea honestly.  The kernel FPU/vector helpers generally don't work
from irq context, and I want to assert that.  Happy to do whatever
version works best for that.