This series fixes a bug in calculating the protection of the reclaim target memcg where we end up using stale effective protection values from the last reclaim operation, instead of completely ignoring the protection of the reclaim target as intended. More detailed explanation and examples in patch 1, which includes the fix. Patches 2 & 3 introduce a selftest case that catches the bug. v2 -> v3: - Refactoring selftest helper reclaim_until (suggested by Roman). - Collected review tags on patch 1 & 3 from Roman (Thanks!). v1 -> v2: - Instead of adding a new helper, extended mem_cgroup_supports_protection() to check if the current memcg is the target memcg, renamed to mem_cgroup_unprotected() which is much easier to reason about (suggested by Roman). - Add a selftest case to catch the bug (suggested by Roman). Yosry Ahmed (3): mm: memcg: fix stale protection of reclaim target memcg selftests: cgroup: refactor proactive reclaim code to reclaim_until() selftests: cgroup: make sure reclaim target memcg is unprotected include/linux/memcontrol.h | 31 +++++-- mm/vmscan.c | 11 ++- .../selftests/cgroup/test_memcontrol.c | 91 +++++++++++-------- 3 files changed, 82 insertions(+), 51 deletions(-) -- 2.39.0.rc0.267.gcb52ba06e7-goog
