This series fixes two test failures in test_zswap observed when running on a single-core VM (-smp 1) with 4GB of RAM.
Patch 1 addresses a race condition in test_zswap_writeback() where waitpid() returns before the exiting child process is switched away by the kernel, causing an immediate write of "+memory" to cgroup.subtree_control to fail with -EBUSY. We fix this by waiting for cgroup.events to report "populated 0". Patch 2 fixes an implicit unsigned conversion bug in test_no_kmem_bypass() where small negative timing differences between debugfs stored_pages and cgroup zswapped bytes caused the comparison to falsely fail due to unsigned promotion. v4 -> v5: - Patch 2: Introduce `cg_read_key_long_long()` to return a `long long` value, and have `cg_read_key_long` use it and convert to `long`. - Patch 2: Make `zswapped` a `long long`. This prevents a overflow on 32-bit platforms (Andrew Morton, Sashiko). v3 -> v4: - Patch 2: Use `long long` for `delta` and `max_delta` and explicitly cast `stored_pages` to avoid integer overflow and implicit unsigned promotion warnings on 32-bit platforms (Andrew Morton, Sashiko). v2 -> v3: - Patch 1: Collect Acked-by from Michal Koutný. - Patch 2: Explicitly cast stored_pages to (long) in delta calculation and inline the return comparison (Michal Koutný). v1 -> v2: - Patch 1: Replace EBUSY retry loop with cg_read_strcmp_wait() waiting for cgroup.events "populated 0" (Michal Koutný). - Patch 1: Clarify task lifecycle in commit description (Yosry Ahmed). - Patch 2: Remove abs() and declare delta/zswapped as signed longs with a signed threshold comparison (Michal Koutný). - Patch 2: Add Fixes tag (Michal Koutný). v4: https://lore.kernel.org/all/[email protected]/ v3: https://lore.kernel.org/all/[email protected]/ v2: https://lore.kernel.org/all/[email protected]/ v1: https://lore.kernel.org/all/[email protected]/ Wilson Felipe Pereira (2): selftests/cgroup: test_zswap: wait for cgroup to unpopulate in test_zswap_writeback selftests/cgroup: test_zswap: fix implicit unsigned promotion bug in test_no_kmem_bypass tools/testing/selftests/cgroup/lib/cgroup_util.c | 17 ++++++++++++----- tools/testing/selftests/cgroup/lib/include/cgroup_util.h | 1 + tools/testing/selftests/cgroup/test_zswap.c | 13 ++++++++----- 3 files changed, 21 insertions(+), 10 deletions(-) --
