linux-kernel - Re: [PATCH 3/4] selftests/mm: add check_folio

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Message-ID: <6A8E4E50-88AD-482F-811C-8707027B1E1C@nvidia.com>
Date: Thu, 07 Aug 2025 13:00:04 -0400
From: Zi Yan <ziy@...dia.com>
To: wang lian <lianux.mm@...il.com>
Cc: Liam.Howlett@...cle.com, akpm@...ux-foundation.org, baohua@...nel.org,
 baolin.wang@...ux.alibaba.com, david@...hat.com, dev.jain@....com,
 linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
 linux-mm@...ck.org, lorenzo.stoakes@...cle.com, mhocko@...e.com,
 npache@...hat.com, rppt@...nel.org, ryan.roberts@....com, shuah@...nel.org,
 surenb@...gle.com, vbabka@...e.cz
Subject: Re: [PATCH 3/4] selftests/mm: add check_folio_orders() helper.

On 6 Aug 2025, at 23:00, wang lian wrote:

> Hi Zi,
>
> Thanks for the patch.
>
> I have a nit suggestion to centralize some of the macro definitions
> for better consistency and reusability.
>
> On [Date of patch], Zi Yan wrote:
>> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
>> ...
>> +#define PGMAP_PRESENT		(1UL << 63)
>> +#define KPF_COMPOUND_HEAD	(1UL << 15)
>> +#define KPF_COMPOUND_TAIL	(1UL << 16)
>> +#define KPF_THP			(1UL << 22)
>> +#define PFN_MASK		((1UL<<55)-1)
>
> Currently, these macros and `PGMAP_PRESENT` are defined locally in
> `vm_util.c`. It would be cleaner to move them to the shared header
> `vm_util.h`.
>
> This would also allow us to consistently use `PM_PRESENT` (from the
> header) instead of the local `PGMAP_PRESENT` duplicate. I noticed the
> patch is already moving in this direction, and we can complete this
> cleanup.
>
> How about a change like this?

I did not know about PM_PRESENT. Sure, will move the code like you
did below. Thanks.

>
> --- a/tools/testing/selftests/mm/vm_util.c
> +++ b/tools/testing/selftests/mm/vm_util.c
> @@ -17,17 +17,6 @@
>  #define STATUS_FILE_PATH "/proc/self/status"
>  #define MAX_LINE_LENGTH 500
>
> -#define PGMAP_PRESENT          (1UL << 63)
> -#define KPF_COMPOUND_HEAD      (1UL << 15)
> -#define KPF_COMPOUND_TAIL      (1UL << 16)
> -#define KPF_THP                        (1UL << 22)
> -#define PFN_MASK     ((1UL<<55)-1)
> -
>  unsigned int __page_size;
>  unsigned int __page_shift;
>
> @@ -360,7 +349,7 @@ static int get_page_flags(uint64_t vpn, int pagemap_file, int kpageflags_file,
>  	 * Treat non-present page as a page without any flag, so that
>  	 * gather_folio_orders() just record the current folio order.
>  	 */
> -	if (!(pfn & PGMAP_PRESENT)) {
> +	if (!(pfn & PM_PRESENT)) {
>  		*flags = 0;
>  		return 0;
>  	}
> --- a/tools/testing/selftests/mm/vm_util.h
> +++ b/tools/testing/selftests/mm/vm_util.h
> @@ -17,6 +17,11 @@
>  #define PM_FILE                        BIT_ULL(61)
>  #define PM_SWAP                        BIT_ULL(62)
>  #define PM_PRESENT             BIT_ULL(63)
> +#define KPF_COMPOUND_HEAD      (1UL << 15)
> +#define KPF_COMPOUND_TAIL      (1UL << 16)
> +#define KPF_THP                        (1UL << 22)
> +#define PFN_MASK     ((1UL<<55)-1)
>
>  extern unsigned int __page_size;
>  extern unsigned int __page_shift;
>
>
> Best regards,
> wang lian


--
Best Regards,
Yan, Zi