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

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Message-ID: <ZrygJqIAz_AqqjcT@infradead.org>
Date: Wed, 14 Aug 2024 05:16:38 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Alistair Popple <apopple@...dia.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Christoph Hellwig <hch@...radead.org>,
	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 10:08:23PM +1000, Alistair Popple wrote:
> I would tend to agree and had the same thought when we found this. At
> least some kind of message (WARN_ON, WARN_ON_ONCE, printk, etc) would
> have made the issue we were debugging much more obvious. FWIW I have
> tested running with a WARN_ON() there and it never fired except in the
> bug scenario.

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.