linux-kernel - Re: [PATCH v5 4/8] mm: Introduce pure page table freeing function

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Message-ID: <646c392c-0a3d-46f6-9d81-c007d6a736da@redhat.com>
Date: Thu, 9 Oct 2025 21:26:22 +0200
From: David Hildenbrand <david@...hat.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
 Kevin Tian <kevin.tian@...el.com>, Jason Gunthorpe <jgg@...dia.com>,
 Jann Horn <jannh@...gle.com>, Vasant Hegde <vasant.hegde@....com>,
 Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...el.com>,
 Alistair Popple <apopple@...dia.com>, Peter Zijlstra <peterz@...radead.org>,
 Uladzislau Rezki <urezki@...il.com>,
 Jean-Philippe Brucker <jean-philippe@...aro.org>,
 Andy Lutomirski <luto@...nel.org>, Yi Lai <yi1.lai@...el.com>
Cc: iommu@...ts.linux.dev, security@...nel.org, x86@...nel.org,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v5 4/8] mm: Introduce pure page table freeing function

On 19.09.25 07:40, Lu Baolu wrote:
> From: Dave Hansen <dave.hansen@...ux.intel.com>
> 
> The pages used for ptdescs are currently freed back to the allocator
> in a single location. They will shortly be freed from a second
> location.
> 
> Create a simple helper that just frees them back to the allocator.
> 
> Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
> Reviewed-by: Kevin Tian <kevin.tian@...el.com>
> ---
>   include/linux/mm.h | 11 ++++++++---
>   1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index f3db3a5ebefe..668d519edc0f 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2884,6 +2884,13 @@ static inline struct ptdesc *pagetable_alloc_noprof(gfp_t gfp, unsigned int orde
>   }
>   #define pagetable_alloc(...)	alloc_hooks(pagetable_alloc_noprof(__VA_ARGS__))
>   
> +static inline void __pagetable_free(struct ptdesc *pt)
> +{
> +	struct page *page = ptdesc_page(pt);
> +
> +	__free_pages(page, compound_order(page));
> +}
> +
>   /**
>    * pagetable_free - Free pagetables
>    * @pt:	The page table descriptor
> @@ -2893,12 +2900,10 @@ static inline struct ptdesc *pagetable_alloc_noprof(gfp_t gfp, unsigned int orde
>    */
>   static inline void pagetable_free(struct ptdesc *pt)
>   {
> -	struct page *page = ptdesc_page(pt);
> -
>   	if (ptdesc_test_kernel(pt))
>   		ptdesc_clear_kernel(pt);
>   
> -	__free_pages(page, compound_order(page));
> +	__pagetable_free(pt);
>   }
>   
>   #if defined(CONFIG_SPLIT_PTE_PTLOCKS)

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers

David / dhildenb