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b=HMQeBh/5DjKrwDG2HtHsTqzr3oTuh45Xn+J8cyc9lI0TmzjP/N1s9r/nywlh347yi h4lgUeq8iGAUN8KILGk3q8JeiFVMJvw3CoLHKwLh3M67Ozwhites3cKQRJhuqbciyR oz8VJ+LY0XSpTl+9LoxSPCjOS6Hk6a+/aaGiNqk4d760PDAI0fBOnm2ta4hcYLCW8S sK6Wmcsv5kXDzGefzFlR+tl5H61dsAna9Cv76OjegaRMdTCJnSGTcqK6Pc8QYApWSJ vsBGFlnwDmGFpy02IyztVzOK47cx5aTJgA34hARbxROOvjMzf61urrTP2WCHvhwOV/ 5pAlC4YTWud2A== From: SeongJae Park To: Cc: SeongJae Park , Andrew Morton , Brendan Higgins , David Gow , Shuah Khan , damon@lists.linux.dev, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v2 00/10] mm/damon: add optional debugging-purpose sanity checks Date: Sun, 1 Mar 2026 09:43:15 -0800 Message-ID: <20260301174327.76849-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: A80ED140004 X-Stat-Signature: rw7yao5wf1jh9ofky19aq8961ai9ft9k X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1772387012-366899 X-HE-Meta: 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 nG3J+Ops iGg0o4CQ1QcEKpYp1iGSsvQReEkTtN+eqNeVONlg8giidETNDAm+42PLrLsM5WRspkLoHxS5Rme1qSS6RYMUOyLp+Xlc+FECk+RNDMhkYrp0Zuj5uVWdXptvc4g+WphTel/B87zswF+d4ZLlxGJZlYQIYJLW87UmLhLuU273mGsNNHd0sOdXys4iv/D5qjV6zhTAEkAIsnOrsbinM0zoWEb8fnCDoE3x/Jv2AeZbXnevLSjsHCGelKmWCl6s7akvSdgOYRmllO3LXlgieQv7NZSWYwA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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/20251231070029.79682-1-sj@kernel.org [2] https://github.com/damonitor/damon-tests/commit/a80fbee55e272f151b4e5809ee85898aea33e6ff Changes from RFC v1 (https://lore.kernel.org/20260221193629.19332-1-sj@kernel.org) - Fix WARN_ON() failure on kunit UML build - Fix Wformat-zero-length issue (https://lore.kernel.org/oe-kbuild-all/202602221352.odZW8x1R-lkp@intel.com/) - 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