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Date: Wed, 4 Mar 2026 16:42:41 +0100
From: Christoph Hellwig <hch@lst.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>, Eric Biggers <ebiggers@kernel.org>,
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Subject: Re: [PATCH 01/25] xor: assert that xor_blocks is not called from
 interrupt context
Message-ID: <20260304154241.GA26451@lst.de>
References: <20260226151106.144735-1-hch@lst.de> <20260226151106.144735-2-hch@lst.de> <20260227142455.GG1282955@noisy.programming.kicks-ass.net> <20260303160050.GB7021@lst.de> <20260303195517.GC2846@sol> <20260304145134.GA21983@lst.de> <20260304151548.GN1395266@noisy.programming.kicks-ass.net>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Wed, Mar 04, 2026 at 04:15:48PM +0100, Peter Zijlstra wrote:
> On Wed, Mar 04, 2026 at 03:51:34PM +0100, Christoph Hellwig wrote:
> 
> > > How about "WARN_ON_ONCE(!preemptible())"?  I think that covers the union
> > > of the context restrictions correctly.  (Compared to in_task(), it
> > > handles the cases where hardirqs or softirqs are disabled.)
> > 
> > Good enough I guess.  Peter?
> 
> Sure. The only caveat with that is that for PREEMPT_COUNT=n this might
> not work, it unconditionally returns 0.

That's a pretty good argument for the lockdep version...