linux-kernel - Re: [PATCH v2] x86/ioremap: Use is_ioremap

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Message-ID: <Zr2L8PUglYWzFTic@infradead.org>
Date: Wed, 14 Aug 2024 22:02:40 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Christoph Hellwig <hch@...radead.org>,
	Alistair Popple <apopple@...dia.com>,
	Max Ramanouski <max8rr8@...il.com>, x86@...nel.org,
	dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
	linux-kernel@...r.kernel.org, jniethe@...dia.com,
	jhubbard@...dia.com, linux-mm@...ck.org
Subject: Re: [PATCH v2] x86/ioremap: Use is_ioremap_addr() in iounmap()

On Wed, Aug 14, 2024 at 04:11:31PM +0200, Thomas Gleixner wrote:
> > Various architectures had either an early ioremap variant that got
> > silently ignored here, or magic carveout that don't get remapped at all.
> > None of this should currently apply to x86, though.
> 
> So I'm inclined to have:
> 
>        if (WARN_ON_ONCE(is_ioremap_addr(addr)))
>        		return;
> 
> in the x86 variant then.

And we should do the same for the generic code eventually after
accounting for all exceptions.  Those should these days mostly be
handled before hand and have explicit address ranges as well, but it'll
need some time to figure all that out.