linux-kernel - Re: [PATCH] tee: shm: fix slab page refcounting

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Message-ID: <20250325195221.ipqmtc36vof4vycb@pengutronix.de>
Date: Tue, 25 Mar 2025 20:52:21 +0100
From: Marco Felsch <m.felsch@...gutronix.de>
To: jens.wiklander@...aro.org, sumit.garg@...nel.org,
	akpm@...ux-foundation.org, vbabka@...e.cz, willy@...radead.org
Cc: op-tee@...ts.trustedfirmware.org, linux-kernel@...r.kernel.org,
	kernel@...gutronix.de
Subject: Re: [PATCH] tee: shm: fix slab page refcounting

On 25-03-25, Marco Felsch wrote:
> Skip manipulating the refcount in case of slab pages according commit
> b9c0e49abfca ("mm: decline to manipulate the refcount on a slab page").
> 
> Fixes: b9c0e49abfca ("mm: decline to manipulate the refcount on a slab page")
> Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> ---
>  drivers/tee/tee_shm.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index daf6e5cfd59a..3d6a3077b6f2 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -19,16 +19,24 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count)
>  {
>  	size_t n;
>  
> -	for (n = 0; n < page_count; n++)
> -		put_page(pages[n]);
> +	for (n = 0; n < page_count; n++) {
> +		struct page *page = pages[n];
> +
> +		if (!PageSlab(page))
> +			put_page(pages[n]);
				  ^
I forgot to change this to page, therefore please ignore this patch.

Regards,
  Marco


> +	}
>  }
>  
>  static void shm_get_kernel_pages(struct page **pages, size_t page_count)
>  {
>  	size_t n;
>  
> -	for (n = 0; n < page_count; n++)
> -		get_page(pages[n]);
> +	for (n = 0; n < page_count; n++) {
> +		struct page *page = pages[n];
> +
> +		if (!PageSlab(page))
> +			get_page(pages[n]);
> +	}
>  }
>  
>  static void release_registered_pages(struct tee_shm *shm)
> -- 
> 2.39.5
> 
> 
>