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b=E0p6niVzr944xjRtcTil+YADxceiaUiz4FBwNlSoB7Ex0G3NTNBcEjrYvdTGRt4Ls uWkiw1JTnBONqF5l7A/3dvoj4mkhSu84SD34HsO7sEH7ZeSOdzIe7/lgx1L5PGUiEF 9Pa9wBg9EcNqEVmm8RaCGn4DkMiCT1j04GP/CLyhf6Y/tBSrMZWnBZ4jqpbFu/OZoC CRGvy6gXw57/KZQmeL5WxsHUTm6JBNpEuiiT7vOodDNOaXJ39bswS4/wVT0hjG181w QLpKD+1whJuDdf+ppU05DKe09W7HF1OsEzPmbtTXcDGDjlyfDhRr6LlxieSx03431u 99aCdy/+V42WA== From: SJ Park To: Andrew Morton Cc: Jiayuan Chen , Brendan Higgins , David Gow , Jiayuan Chen , SJ Park , Shu Anzai , damon@lists.linux.dev, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 2/2] mm/damon/tests/core-kunit: test split above max_nr_regions/2 Date: Mon, 29 Jun 2026 07:56:29 -0700 Message-ID: <20260629145630.134891-3-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260629145630.134891-1-sj@kernel.org> References: <20260629145630.134891-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: CA158140006 X-Stat-Signature: wi8kp6hqzhwtd4ij1oozorfcrx4oknqy X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1782745000-841233 X-HE-Meta: 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 EmzDfKKA 9PwtAIGzXafwxqOpKzfNLHEmVUcU+U/hl85kWihLwJ7gVg2rPYenZNGoewYqkXv0hT8DM9GfCkRmTFlagg1Ru83uwz6WOEkIRF8Da0NVEVK+b6uc2+WnSoG65jQJp+LT0DM7uo/7cAo/q8X6FIv+ZSRBVT+HMBANAKKzzLQdKHCysJMJqrxwxgUFIQqmq+gkMMss8NBQBK/Mq8kPbCd7S97h/AYkaL4CqydwKZCptGqi50zQg/Ri+SCk427el9ClttzWJU6TbWT4b35kHAFNc4g6cPKb64EJzhJXHMPDwXnuSCr9fEiv3scSLpUEf8ep5MWncXFdvu5agfUNpnNYN4CV6L9Qtzei8VaHkkHZMSc80SvugbOd2LfzPTEBJAx9hwGv+cwZKL979VEv0Lo/ScNZeskMtRSnjyjTt5B/lj4t83Dc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Jiayuan Chen Add a test that exercises kdamond_split_regions() when the total region count is already above max_nr_regions / 2, asserting that the function still splits a fraction of the regions (makes progress) and does not overshoot max_nr_regions. The region size and min_region_sz are picked so the split arithmetic does not depend on the page size. All tests pass: damon: pass:31 fail:0 skip:0 total:31 Totals: pass:31 fail:0 skip:0 total:31 Link: https://lore.kernel.org/20260626085851.70754-3-jiayuan.chen@linux.dev Cc: Jiayuan Chen Signed-off-by: Jiayuan Chen Reviewed-by: SJ Park Cc: SJ Park Cc: Andrew Morton Cc: Shu Anzai Signed-off-by: SJ Park --- mm/damon/tests/core-kunit.h | 64 +++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h index c5f5124c3d1f4..a00168730445d 100644 --- a/mm/damon/tests/core-kunit.h +++ b/mm/damon/tests/core-kunit.h @@ -335,6 +335,69 @@ static void damon_test_split_regions_of(struct kunit *test) damon_destroy_ctx(c); } +/* + * When the total region count is already above max_nr_regions / 2, + * kdamond_split_regions() must keep refining the resolution by splitting a + * fraction of the regions (making progress), without exceeding + * max_nr_regions. + */ +static void damon_test_split_above_half_progresses(struct kunit *test) +{ + struct damon_ctx *c; + struct damon_target *t; + struct damon_region *r; + unsigned long start; + unsigned int nr_before, nr_after, i; + const unsigned int nr_init = 760; + const unsigned long region_sz = 100; + + c = damon_new_ctx(); + if (!c) + kunit_skip(test, "ctx alloc fail"); + + /* Keep the split arithmetic independent of the page size */ + c->min_region_sz = 1; + c->attrs.min_nr_regions = 10; + c->attrs.max_nr_regions = 1500; + + t = damon_new_target(); + if (!t) { + damon_destroy_ctx(c); + kunit_skip(test, "target alloc fail"); + } + + for (i = 0; i < nr_init; i++) { + start = i * region_sz; + r = damon_new_region(start, start + region_sz); + if (!r) { + damon_free_target(t); + damon_destroy_ctx(c); + kunit_skip(test, "region alloc fail"); + } + r->nr_accesses = (i & 1) ? 0 : 100; + r->age = 5; + damon_add_region(r, t); + } + + damon_add_target(c, t); + + nr_before = damon_nr_regions(t); + /* Above max_nr_regions / 2, so the blanket-split path is skipped */ + KUNIT_EXPECT_GT(test, (unsigned long)nr_before, + c->attrs.max_nr_regions / 2); + + kdamond_split_regions(c); + + nr_after = damon_nr_regions(t); + /* Still made progress ... */ + KUNIT_EXPECT_GT(test, nr_after, nr_before); + /* ... but did not overshoot the configured maximum */ + KUNIT_EXPECT_LE(test, (unsigned long)nr_after, + c->attrs.max_nr_regions); + + damon_destroy_ctx(c); +} + static void damon_test_ops_registration(struct kunit *test) { struct damon_ctx *c = damon_new_ctx(); @@ -1491,6 +1554,7 @@ static struct kunit_case damon_test_cases[] = { KUNIT_CASE(damon_test_merge_two), KUNIT_CASE(damon_test_merge_regions_of), KUNIT_CASE(damon_test_split_regions_of), + KUNIT_CASE(damon_test_split_above_half_progresses), KUNIT_CASE(damon_test_ops_registration), KUNIT_CASE(damon_test_set_regions), KUNIT_CASE(damon_test_nr_accesses_to_accesses_bp), -- 2.47.3