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arm64: mm: warn once for ioremap attempts on RAM mappings

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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@debian.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Breno Leitao 2025-12-22 07:28:55 -08:00 • committed by Will Deacon
parent f22c81bebf
commit 53f45f045c
1 changed files with 2 additions and 1 deletions
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3
arch/arm64/mm/ioremap.c
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@ -24,7 +24,8 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
return NULL;
/* Don't allow RAM to be mapped. */
if (WARN_ON(pfn_is_map_memory(__phys_to_pfn(phys_addr))))
if (WARN_ONCE(pfn_is_map_memory(__phys_to_pfn(phys_addr)),
"ioremap attempted on RAM pfn\n"))
return NULL;
/*