[PATCH v4 0/7] selftests/cgroup: improve zswap tests robustness and support large page sizes

[Li Wang <liwang@redhat.com>]

This patchset aims to fix various spurious failures and improve the overall
robustness of the cgroup zswap selftests.

The primary motivation is to make the tests compatible with architectures
that use non-4K page sizes (such as 64K on ppc64le and arm64). Currently,
the tests rely heavily on hardcoded 4K page sizes and fixed memory limits.
On 64K page size systems, these hardcoded values lead to sub-page granularity
accesses, incorrect page count calculations, and insufficient memory pressure
to trigger zswap writeback, ultimately causing the tests to fail.

Additionally, this series addresses OOM kills occurring in test_swapin_nozswap
by dynamically scaling memory limits, and prevents spurious test failures
when zswap is built into the kernel but globally disabled.

Changes in v4:
  Patch 2: Use %zu format specifier when printing pagesize.
  Patch 4: Use page_size instead of BUF_SIZE in test_memcontrol.c.
  Patch 6: Print the expected swap amount in KB instead of MB.

Tested on v6.12:
  across x86_64, aarch64, ppc64le archs.

Li Wang (7):
  selftests/cgroup: skip test_zswap if zswap is globally disabled
  selftests/cgroup: avoid OOM in test_swapin_nozswap
  selftests/cgroup: use runtime page size for zswpin check
  selftests/cgroup: rename PAGE_SIZE to BUF_SIZE in cgroup_util
  selftests/cgroup: replace hardcoded page size values in test_zswap
  selftest/cgroup: fix zswap test_no_invasive_cgroup_shrink on large
    pagesize system
  selftest/cgroup: fix zswap attempt_writeback() on 64K pagesize system

 .../selftests/cgroup/lib/cgroup_util.c        | 18 ++---
 .../cgroup/lib/include/cgroup_util.h          |  4 +-
 tools/testing/selftests/cgroup/test_core.c    |  2 +-
 tools/testing/selftests/cgroup/test_freezer.c |  2 +-
 .../selftests/cgroup/test_memcontrol.c        | 15 ++--
 tools/testing/selftests/cgroup/test_zswap.c   | 79 +++++++++++++------
 6 files changed, 74 insertions(+), 46 deletions(-)

-- 
2.53.0