linux-kernel - Re: [PATCH v4 5/7] selftest/mm: Extract sz2ord function into vm

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Message-ID: <dd423a91-f9ef-4718-9452-fa85a60f1331@lucifer.local>
Date: Wed, 13 Aug 2025 15:31:53 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Usama Arif <usamaarif642@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, david@...hat.com,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org, corbet@....net,
        rppt@...nel.org, surenb@...gle.com, mhocko@...e.com,
        hannes@...xchg.org, baohua@...nel.org, shakeel.butt@...ux.dev,
        riel@...riel.com, ziy@...dia.com, laoar.shao@...il.com,
        dev.jain@....com, baolin.wang@...ux.alibaba.com, npache@...hat.com,
        Liam.Howlett@...cle.com, ryan.roberts@....com, vbabka@...e.cz,
        jannh@...gle.com, Arnd Bergmann <arnd@...db.de>, sj@...nel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        kernel-team@...a.com
Subject: Re: [PATCH v4 5/7] selftest/mm: Extract sz2ord function into
 vm_util.h

On Wed, Aug 13, 2025 at 02:55:40PM +0100, Usama Arif wrote:
> The function already has 2 uses and will have a 3rd one
> in prctl selftests. The pagesize argument is added into
> the function, as it's not a global variable anymore.
> No functional change intended with this patch.
>
> Suggested-by: David Hildenbrand <david@...hat.com>
> Signed-off-by: Usama Arif <usamaarif642@...il.com>

LGTM, so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  tools/testing/selftests/mm/cow.c            | 12 ++++--------
>  tools/testing/selftests/mm/uffd-wp-mremap.c |  9 ++-------
>  tools/testing/selftests/mm/vm_util.h        |  5 +++++
>  3 files changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
> index 90ee5779662f3..a568fe629b094 100644
> --- a/tools/testing/selftests/mm/cow.c
> +++ b/tools/testing/selftests/mm/cow.c
> @@ -41,10 +41,6 @@ static size_t hugetlbsizes[10];
>  static int gup_fd;
>  static bool has_huge_zeropage;
>
> -static int sz2ord(size_t size)
> -{
> -	return __builtin_ctzll(size / pagesize);
> -}
>
>  static int detect_thp_sizes(size_t sizes[], int max)
>  {
> @@ -57,7 +53,7 @@ static int detect_thp_sizes(size_t sizes[], int max)
>  	if (!pmdsize)
>  		return 0;
>
> -	orders = 1UL << sz2ord(pmdsize);
> +	orders = 1UL << sz2ord(pmdsize, pagesize);
>  	orders |= thp_supported_orders();
>
>  	for (i = 0; orders && count < max; i++) {
> @@ -1216,8 +1212,8 @@ static void run_anon_test_case(struct test_case const *test_case)
>  		size_t size = thpsizes[i];
>  		struct thp_settings settings = *thp_current_settings();
>
> -		settings.hugepages[sz2ord(pmdsize)].enabled = THP_NEVER;
> -		settings.hugepages[sz2ord(size)].enabled = THP_ALWAYS;
> +		settings.hugepages[sz2ord(pmdsize, pagesize)].enabled = THP_NEVER;
> +		settings.hugepages[sz2ord(size, pagesize)].enabled = THP_ALWAYS;
>  		thp_push_settings(&settings);
>
>  		if (size == pmdsize) {
> @@ -1868,7 +1864,7 @@ int main(void)
>  	if (pmdsize) {
>  		/* Only if THP is supported. */
>  		thp_read_settings(&default_settings);
> -		default_settings.hugepages[sz2ord(pmdsize)].enabled = THP_INHERIT;
> +		default_settings.hugepages[sz2ord(pmdsize, pagesize)].enabled = THP_INHERIT;
>  		thp_save_settings();
>  		thp_push_settings(&default_settings);
>
> diff --git a/tools/testing/selftests/mm/uffd-wp-mremap.c b/tools/testing/selftests/mm/uffd-wp-mremap.c
> index 13ceb56289701..b2b6116e65808 100644
> --- a/tools/testing/selftests/mm/uffd-wp-mremap.c
> +++ b/tools/testing/selftests/mm/uffd-wp-mremap.c
> @@ -19,11 +19,6 @@ static size_t thpsizes[20];
>  static int nr_hugetlbsizes;
>  static size_t hugetlbsizes[10];
>
> -static int sz2ord(size_t size)
> -{
> -	return __builtin_ctzll(size / pagesize);
> -}
> -
>  static int detect_thp_sizes(size_t sizes[], int max)
>  {
>  	int count = 0;
> @@ -87,9 +82,9 @@ static void *alloc_one_folio(size_t size, bool private, bool hugetlb)
>  		struct thp_settings settings = *thp_current_settings();
>
>  		if (private)
> -			settings.hugepages[sz2ord(size)].enabled = THP_ALWAYS;
> +			settings.hugepages[sz2ord(size, pagesize)].enabled = THP_ALWAYS;
>  		else
> -			settings.shmem_hugepages[sz2ord(size)].enabled = SHMEM_ALWAYS;
> +			settings.shmem_hugepages[sz2ord(size, pagesize)].enabled = SHMEM_ALWAYS;
>
>  		thp_push_settings(&settings);
>
> diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
> index 148b792cff0fc..e5cb72bf3a2ab 100644
> --- a/tools/testing/selftests/mm/vm_util.h
> +++ b/tools/testing/selftests/mm/vm_util.h
> @@ -135,6 +135,11 @@ static inline void log_test_result(int result)
>  	ksft_test_result_report(result, "%s\n", test_name);
>  }
>
> +static inline int sz2ord(size_t size, size_t pagesize)
> +{
> +	return __builtin_ctzll(size / pagesize);
> +}
> +
>  void *sys_mremap(void *old_address, unsigned long old_size,
>  		 unsigned long new_size, int flags, void *new_address);
>
> --
> 2.47.3
>