Re: [PATCH v2 1/4] drivers/iommu: Add page_ext for IOMMU_DEBUG_PAGEALLOC

Randy Dunlap
2025-11-06T19:50:15Z

> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 70d29b14d851..6b5e9a2d936a 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -383,4 +383,19 @@ config SPRD_IOMMU
>
> Say Y here if you want to use the multimedia devices listed above.
>
> +config IOMMU_DEBUG_PAGEALLOC
> + bool "Debug page memory allocations against IOMMU"
> + depends on DEBUG_PAGEALLOC && IOMMU_API && PAGE_EXTENSION
> + help
> + This config checks that a page is freed(unmapped) or mapped by the
> + kernel is not mapped in any IOMMU domain. It can help with debugging
> + use-after-free or out-of-bound maps from drivers doing DMA through
> + the IOMMU API.
> + This santaizer can have false-negative cases where some problems

sanitizer

> + won't be detected.
> + Expect overhead when enabling this and enabling the kernel command
> + line iommu.debug_pagealloc.
> +
> + If unsure, say N here.
> +
> endif # IOMMU_SUPPORT

--
~Randy