[PATCH v2 1/2] selftest/vm: Use correct PAGE_SHIFT value for ppc64

[Aneesh Kumar K V]

On 2/11/22 18:58, Mike Rapoport wrote:
> Hi Aneesh,
> 
> On Fri, Feb 11, 2022 at 05:22:13PM +0530, Aneesh Kumar K V wrote:
>> On 2/11/22 16:03, Mike Rapoport wrote:
>>> On Fri, Feb 11, 2022 at 12:03:28PM +0530, Aneesh Kumar K.V wrote:
>>>> Keep it simple by using a #define and limiting hugepage size to 2M.
>>>> This keeps the test simpler instead of dynamically finding the page size
>>>> and huge page size.
>>>>
>>>> Without this tests are broken w.r.t reading /proc/self/pagemap
>>>>
>>>> 	if (pread(pagemap_fd, ent, sizeof(ent),
>>>> 			(uintptr_t)ptr >> (PAGE_SHIFT - 3)) != sizeof(ent))
>>>> 		err(2, "read pagemap");
>>>>
>>>> Cc: Shuah Khan <shuah at kernel.org>
>>>> Cc: linux-kselftest at vger.kernel.org
>>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
>>>> ---
>>>>    tools/testing/selftests/vm/ksm_tests.c        | 9 ++++++++-
>>>>    tools/testing/selftests/vm/transhuge-stress.c | 9 ++++++++-
>>>>    2 files changed, 16 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
>>>> index 1436e1a9a3d3..cae72872152b 100644
>>>> --- a/tools/testing/selftests/vm/ksm_tests.c
>>>> +++ b/tools/testing/selftests/vm/ksm_tests.c
>>>> @@ -22,7 +22,14 @@
>>>>    #define KSM_MERGE_ACROSS_NODES_DEFAULT true
>>>>    #define MB (1ul << 20)
>>>> -#define PAGE_SHIFT 12
>>>> +#ifdef __powerpc64__
>>>> +#define PAGE_SHIFT	16
>>>> +#else
>>>> +#define PAGE_SHIFT	12
>>>> +#endif
>>>
>>> Page size can be other than 4096 for other configurations as well. And even
>>> on ppc64 it's not necessarily 64k.
>>>
>>
>> But most common test config is with 64K page size.
>>
>>> Ideally page size in selftests/vm should be sysconf(_SC_PAGESIZE)
>>
>>
>> yes. As explained in commit message, the idea was to keep it simpler.
> 
> I think it's simple enough (compile tested on x86 only):
> 
>  From 219577d87041f19f2c00dc7c23e0fd5aad8b02d5 Mon Sep 17 00:00:00 2001
> From: Mike Rapoport <rppt at linux.ibm.com>
> Date: Fri, 11 Feb 2022 15:24:13 +0200
> Subject: [PATCH] selftest/vm: add helpers to detect PAGE_SIZE and PAGE_SHIFT
> 
> PAGE_SIZE is not 4096 in many configurations, particularily ppc64 uses
> 64K pages in majority of cases.
> 
> Add helpers to detect PAGE_SIZE and PAGE_SHIFT dynamically.
> 
> Signed-off-by: Mike Rapoport <rppt at linux.ibm.com>
> ---
>   tools/testing/selftests/vm/gup_test.c         |  3 +-
>   tools/testing/selftests/vm/ksm_tests.c        |  8 +----
>   tools/testing/selftests/vm/transhuge-stress.c |  9 ++----
>   tools/testing/selftests/vm/util.h             | 29 +++++++++++++++++++
>   4 files changed, 34 insertions(+), 15 deletions(-)
>   create mode 100644 tools/testing/selftests/vm/util.h
> 
> diff --git a/tools/testing/selftests/vm/gup_test.c b/tools/testing/selftests/vm/gup_test.c
> index fe043f67798b..cda837a14736 100644
> --- a/tools/testing/selftests/vm/gup_test.c
> +++ b/tools/testing/selftests/vm/gup_test.c
> @@ -10,8 +10,9 @@
>   #include <assert.h>
>   #include "../../../../mm/gup_test.h"
>   
> +#include "util.h"
> +
>   #define MB (1UL << 20)
> -#define PAGE_SIZE sysconf(_SC_PAGESIZE)
>   
>   /* Just the flags we need, copied from mm.h: */
>   #define FOLL_WRITE	0x01	/* check pte is writable */
> diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
> index cae72872152b..7faafd24446f 100644
> --- a/tools/testing/selftests/vm/ksm_tests.c
> +++ b/tools/testing/selftests/vm/ksm_tests.c
> @@ -12,6 +12,7 @@
>   
>   #include "../kselftest.h"
>   #include "../../../../include/vdso/time64.h"
> +#include "util.h"
>   
>   #define KSM_SYSFS_PATH "/sys/kernel/mm/ksm/"
>   #define KSM_FP(s) (KSM_SYSFS_PATH s)
> @@ -22,17 +23,10 @@
>   #define KSM_MERGE_ACROSS_NODES_DEFAULT true
>   #define MB (1ul << 20)
>   
> -#ifdef __powerpc64__
> -#define PAGE_SHIFT	16
> -#else
> -#define PAGE_SHIFT	12
> -#endif
>   /*
>    * On ppc64 this will only work with radix 2M hugepage size
>    */
>   #define HPAGE_SHIFT 21
> -
> -#define PAGE_SIZE (1 << PAGE_SHIFT)
>   #define HPAGE_SIZE (1 << HPAGE_SHIFT)
>   
>   #define PAGEMAP_PRESENT(ent)	(((ent) & (1ull << 63)) != 0)
> diff --git a/tools/testing/selftests/vm/transhuge-stress.c b/tools/testing/selftests/vm/transhuge-stress.c
> index b1f8d98355c5..baf90a745d28 100644
> --- a/tools/testing/selftests/vm/transhuge-stress.c
> +++ b/tools/testing/selftests/vm/transhuge-stress.c
> @@ -16,17 +16,12 @@
>   #include <string.h>
>   #include <sys/mman.h>
>   
> -#ifdef __powerpc64__
> -#define PAGE_SHIFT	16
> -#else
> -#define PAGE_SHIFT	12
> -#endif
> +#include "util.h"
> +
>   /*
>    * On ppc64 this will only work with radix 2M hugepage size
>    */
>   #define HPAGE_SHIFT 21
> -
> -#define PAGE_SIZE (1 << PAGE_SHIFT)
>   #define HPAGE_SIZE (1 << HPAGE_SHIFT)
>   
>   #define PAGEMAP_PRESENT(ent)	(((ent) & (1ull << 63)) != 0)
> diff --git a/tools/testing/selftests/vm/util.h b/tools/testing/selftests/vm/util.h
> new file mode 100644
> index 000000000000..1c85d7583bac
> --- /dev/null
> +++ b/tools/testing/selftests/vm/util.h
> @@ -0,0 +1,29 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef __KSELFTEST_VM_UTIL_H
> +#define __KSELFTEST_VM_UTIL_H
> +
> +#include <string.h> /* ffsl() */
> +#include <unistd.h> /* _SC_PAGESIZE */
> +
> +static unsigned __page_size;
> +static unsigned __page_shift;
> +
> +static inline unsigned page_size(void)
> +{
> +	if (!__page_size)
> +		__page_size = sysconf(_SC_PAGESIZE);
> +	return __page_size;
> +}
> +
> +static inline unsigned page_shift(void)
> +{
> +	if (!__page_shift)
> +		__page_shift = (ffsl(page_size()) - 1);
> +	return __page_shift;
> +}
> +
> +#define PAGE_SHIFT	(page_shift())
> +#define PAGE_SIZE	(page_size())
> +
> +#endif /* __KSELFTEST_VM_UTIL_H */

This is on top of patch 1 I sent i guess. Should I add it to the series 
because v2 also consolidate allocate_transhuge()? Or do you want to sent 
it as an independent patch?

-aneesh