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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782464402; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RiF+ZZp+CVU1sZqeDDRKvFPYiBeZ08llaMDiB0IH+P0=; b=BZC2sX83iCPGiP8u4V/j2JFHHAvan3ttXTMNSWEawRTRc+lBxqRdNidDx4QEoApuNeJhAT BgdopX6rtN9K9+8I+cLEXF9ye8+IOW3/ZuUeXXpWrpCbv6N7VonvJYEtiyZ43uTJ3qsC3P ZqY5ujY+QkxJyy2C1NoBP7ZADQVxNFU= From: Jiayuan Chen To: damon@lists.linux.dev Cc: jiayuan.chen@shopee.com, Jiayuan Chen , SeongJae Park , Andrew Morton , Shu Anzai , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/2] mm/damon/tests/core-kunit: test split above max_nr_regions/2 Date: Fri, 26 Jun 2026 16:58:38 +0800 Message-ID: <20260626085851.70754-3-jiayuan.chen@linux.dev> In-Reply-To: <20260626085851.70754-1-jiayuan.chen@linux.dev> References: <20260626085851.70754-1-jiayuan.chen@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 9CC3A140004 X-Stat-Signature: pr5dfacuogon99nmsbgf8danxpqm7ph6 X-HE-Tag: 1782464403-254549 X-HE-Meta: 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 mVftsSzX wTa0GB31MbpDs5OCKkIiz0oGe8LdTYVsq7+u90k/rIWc1BsVTmlNhwuc08wr14KvqT8WV5OBJbc08OFQ1Y49KWvo869/PIzy4B5UVSeaTA4uP+kJyOsqRQBrrArHF7qMETnuHSseWHljW5EIPTjeD/kkyElIUNMEv3XoIijB0EZgWVr1ZrOIJQ6umpzbMUrBDtrc9Ex/O5chV9Um9gG5BVgSwgX8eIsZJpHGZLK0Z0OgAgXSMKrls2FggXt2BI/CpJGep4PxOa4dwmgNdk20oTmbEtEvw2Ph8K1zWIywOe7IJwFO/PVTAnjTF5LMvtVWN+r4gIYc9BM1QgGJSY+rRcwNgvQ== 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 Cc: Jiayuan Chen Signed-off-by: Jiayuan Chen --- 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 29fbe495e532..6fe7abcd670d 100644 --- a/mm/damon/tests/core-kunit.h +++ b/mm/damon/tests/core-kunit.h @@ -341,6 +341,69 @@ 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(); @@ -1521,6 +1584,7 @@ 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), -- 2.43.0