linux-kernel - Re: [PATCH v5 1/4] iommu: Add page_ext for IOMMU_DEBUG

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Message-ID: <42286636-2fca-4658-a79d-145ad1c37b37@kernel.org>
Date: Tue, 6 Jan 2026 19:50:33 +0100
From: "David Hildenbrand (Red Hat)" <david@...nel.org>
To: Mostafa Saleh <smostafa@...gle.com>, linux-mm@...ck.org,
 iommu@...ts.linux.dev, linux-kernel@...r.kernel.org,
 linux-doc@...r.kernel.org
Cc: corbet@....net, joro@...tes.org, will@...nel.org, robin.murphy@....com,
 akpm@...ux-foundation.org, vbabka@...e.cz, surenb@...gle.com,
 mhocko@...e.com, jackmanb@...gle.com, hannes@...xchg.org, ziy@...dia.com,
 lorenzo.stoakes@...cle.com, Liam.Howlett@...cle.com, rppt@...nel.org,
 xiaqinxin@...wei.com, baolu.lu@...ux.intel.com, rdunlap@...radead.org
Subject: Re: [PATCH v5 1/4] iommu: Add page_ext for IOMMU_DEBUG_PAGEALLOC

On 1/6/26 17:21, Mostafa Saleh wrote:
> Add a new config IOMMU_DEBUG_PAGEALLOC, which registers new data to
> page_ext.
> 
> This config will be used by the IOMMU API to track pages mapped in
> the IOMMU to catch drivers trying to free kernel memory that they
> still map in their domains, causing all types of memory corruption.
> 
> This behaviour is disabled by default and can be enabled using
> kernel cmdline iommu.debug_pagealloc.
> 
> Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Signed-off-by: Mostafa Saleh <smostafa@...gle.com>
> ---

[...]

> +#endif /* __LINUX_IOMMU_DEBUG_PAGEALLOC_H */
> diff --git a/mm/page_ext.c b/mm/page_ext.c
> index d7396a8970e5..297e4cd8ce90 100644
> --- a/mm/page_ext.c
> +++ b/mm/page_ext.c
> @@ -11,6 +11,7 @@
>   #include <linux/page_table_check.h>
>   #include <linux/rcupdate.h>
>   #include <linux/pgalloc_tag.h>
> +#include <linux/iommu-debug-pagealloc.h>
>   
>   /*
>    * struct page extension
> @@ -89,6 +90,9 @@ static struct page_ext_operations *page_ext_ops[] __initdata = {
>   #ifdef CONFIG_PAGE_TABLE_CHECK
>   	&page_table_check_ops,
>   #endif
> +#ifdef CONFIG_IOMMU_DEBUG_PAGEALLOC
> +	&page_iommu_debug_ops,
> +#endif
>   };
>   
>   unsigned long page_ext_size;

The MM bits LGTM

Acked-by: David Hildenbrand (Red Hat) <david@...nel.org>

-- 
Cheers

David