Re: [PATCH v4 5/7] selftests/cgroup: replace hardcoded page size values in test_zswap

[Yosry Ahmed <yosry@kernel.org>]

On Sat, Mar 21, 2026 at 11:11 PM Li Wang <liwang@redhat.com> wrote:
>
> test_zswap uses hardcoded values of 4095 and 4096 throughout as page
> stride and page size, which are only correct on systems with a 4K page
> size. On architectures with larger pages (e.g., 64K on arm64 or ppc64),
> these constants cause memory to be touched at sub-page granularity,
> leading to inefficient access patterns and incorrect page count
> calculations, which can cause test failures.
>
> Replace all hardcoded 4095 and 4096 values with a global pagesize
> variable initialized from sysconf(_SC_PAGESIZE) at startup, and remove
> the redundant local sysconf() calls scattered across individual
> functions. No functional change on 4K page size systems.
>
> Signed-off-by: Li Wang <liwang@redhat.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Michal Koutný <mkoutny@suse.com>
> Cc: Muchun Song <muchun.song@linux.dev>
> Cc: Nhat Pham <nphamcs@gmail.com>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Roman Gushchin <roman.gushchin@linux.dev>
> Cc: Shakeel Butt <shakeel.butt@linux.dev>
> Cc: Yosry Ahmed <yosryahmed@google.com>

Acked-by: Yosry Ahmed <yosry@kernel.org>