Re: [PATCH v2 1/2] selftests/cgroup: Fix hardcoded page size in test_percpu_basic

[Sayali Patil <sayalip@linux.ibm.com>]

On 01/05/26 07:50, Li Wang wrote:
> MAX_VMSTAT_ERROR uses a hardcoded page size of 4096, which assumes
> 4K pages. This causes test_percpu_basic to fail on systems where
> the kernel is configured with a larger page size, such as aarch64
> systems using 16K or 64K pages, where the maximum permissible
> discrepancy between memory.current and percpu charges is
> proportionally larger.
> 
> Replace the hardcoded 4096 with sysconf(_SC_PAGESIZE) to correctly
> derive the page size at runtime regardless of the underlying
> architecture or kernel configuration.
> 
> Signed-off-by: Li Wang <li.wang@linux.dev>
> Cc: Waiman Long <longman@redhat.com>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Shakeel Butt <shakeelb@google.com>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Acked-by: Waiman Long <longman@redhat.com>
> ---
>   tools/testing/selftests/cgroup/test_kmem.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c
> index eeabd34bf08..249d7911306 100644
> --- a/tools/testing/selftests/cgroup/test_kmem.c
> +++ b/tools/testing/selftests/cgroup/test_kmem.c
> @@ -24,7 +24,7 @@
>    * the maximum discrepancy between charge and vmstat entries is number
>    * of cpus multiplied by 64 pages.
>    */
> -#define MAX_VMSTAT_ERROR (4096 * 64 * get_nprocs())
> +#define MAX_VMSTAT_ERROR (sysconf(_SC_PAGESIZE) * 64 * get_nprocs())
>   
>   #define KMEM_DEAD_WAIT_RETRIES        80
>   

Reviewed-by: Sayali Patil <sayalip@linux.ibm.com>

Thanks,
Sayali