DAMON code has a few assumptions that can be critical if violated. Validating the assumptions in code can be useful at finding such critical bugs. I was actually adding some such additional sanity checks in my personal tree, and those were useful at finding bugs that I made during the development of new patches. We also found [1] sometimes the assumptions are misunderstood. The validation can work as good documentation for such cases.
Add some of such debugging purpose sanity checks. Because those additional checks can impose more overhead, make those only optional via new config, CONFIG_DAMON_DEBUG_SANITY, that is recommended for only development and test setups. And as recommended, enable it for DAMON kunit tests and selftests. Note that the verification only WARN_ON() for each of the insanity. The developer or tester may better to set panic_on_oops together, like damon-tests/corr did [2]. [1] https://lore.kernel.org/[email protected] [2] https://github.com/damonitor/damon-tests/commit/a80fbee55e272f151b4e5809ee85898aea33e6ff Changes from RFC v1 (https://lore.kernel.org/[email protected]) - Fix WARN_ON() failure on kunit UML build - Fix Wformat-zero-length issue (https://lore.kernel.org/oe-kbuild-all/[email protected]/) - Rebase to latest mm-new - Make warning message less verbose - Use WARN_ONCE() condition - Do the verification asap - Minor cleanups SeongJae Park (10): mm/damon: add CONFIG_DAMON_DEBUG_SANITY mm/damon/core: add damon_new_region() debug_sanity check mm/damon/core: add damon_del_region() debug_sanity check mm/damon/core: add damon_nr_regions() debug_sanity check mm/damon/core: add damon_merge_two_regions() debug_sanity check mm/damon/core: add damon_merge_regions_of() debug_sanity check mm/damon/core: add damon_split_region_at() debug_sanity check mm/damon/core: add damon_reset_aggregated() debug_sanity check mm/damon/tests/.kunitconifg: enable DAMON_DEBUG_SANITY selftests/damon/config: enable DAMON_DEBUG_SANITY mm/damon/Kconfig | 11 +++ mm/damon/core.c | 109 +++++++++++++++++++++++++++ mm/damon/tests/.kunitconfig | 3 + tools/testing/selftests/damon/config | 1 + 4 files changed, 124 insertions(+) base-commit: b511f483f5fc7e85ad60679181503f16937feb6e -- 2.47.3
