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

[Mostafa Saleh <smostafa@google.com>]

On Thu, Nov 06, 2025 at 11:50:11AM -0800, Randy Dunlap wrote:
> 
> 
> > 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

I will fix it.

Thanks,
Mostafa

> 
> > +	  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
>