linux-kernel - Re: [PATCH] arm64: mm: warn once for ioremap attempts on RAM mappings

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Message-ID: <aWopx48U6A090aIj@arm.com>
Date: Fri, 16 Jan 2026 12:06:31 +0000
From: Catalin Marinas <catalin.marinas@....com>
To: Breno Leitao <leitao@...ian.org>
Cc: Will Deacon <will@...nel.org>, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, kernel-team@...a.com, clm@...com
Subject: Re: [PATCH] arm64: mm: warn once for ioremap attempts on RAM mappings

On Mon, Dec 22, 2025 at 07:28:55AM -0800, Breno Leitao wrote:
> Replace WARN_ON with WARN_ONCE when detecting attempts to ioremap
> RAM. This prevents log spam when a misbehaving driver repeatedly tries
> to map RAM via ioremap.
> 
> A single warning is more than enough to show the broken code path, and
> extra reports don't add extra information.
> 
> Warning floods have been seen in production environments where broken
> external drivers hit this code path thousand of times, causing
> unnecessary messages to be printed and pressure on the serial console.
> 
> Signed-off-by: Breno Leitao <leitao@...ian.org>

It looks fine to me but it's not urgent for 6.19, so I'll leave it to
Will.

Acked-by: Catalin Marinas <catalin.marinas@....com>