From nobody Thu Sep 24 18:38:14 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF0064B66C2; Mon, 21 Sep 2026 15:24:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790004293; cv=none; b=gDtBjJ1Ytj0SSkaKMHH+kKZHX25OAuGonJ8sAKAZT7POp+wTB8gvnKwyvZCEH2e2MvhLlWLQUYGLzWAz9tvRf8kphwBpGJHn8RR1r0Z4P0oFH6y6hbbNoy1yleOV0TX27lqvgnNV4PpCgMlDHzpr7OuFjoqeUHgPUzcyZ23+qD0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790004293; c=relaxed/simple; bh=BoXoNj7iWXe4GhIAFX6wcc7SgGaQC7uegRD3ZFkwIyo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IVtD0y1t4JkCd6sfjz1N4UhiZoD17HRZD8kXCWFkqKLO0BI62kUA4NG1WNk1w6b+NwZd7raix2L+q5tA0sPishcllXPPet8gYdrXmt8eBle2s6PeKAH3CQjiBzcBTbHwgASL+2+tyoklnFarrATa2R4pTxYuTiO8VFqipUdzb90= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SYuNaofm; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="SYuNaofm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCD611F00893; Mon, 21 Sep 2026 15:24:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790004291; bh=lhYZozQNlJ+OrzQg2fSGExZ1q1RyH+RT/pmgwytGQEE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=SYuNaofmP9J/SPxw18OqPmlkKyGRAXDtPJwkLz2ge4Zt4g73J1V+L8QQbBE3zxTl1 mzN/DcuVT9m2uTdBhhMCTQYbc/oeYG41Qspbm2xjDNfvKbSmNpl3voMqE4Cl3pPSzq HivvICv7TDF/CgK3KyLQMlMj7U0V3JslI+Nb+lHh/qLfXSECHfRWbm0zxwI+BVwlKm PoHGxbQrKVRuvBLyHb2/r8gedFlZAfrBlfodvXLA/s0B/2wZu16UB2dJGtszWXHX9p JV/xiDbGnIjztmy6rl48urDy4DSDr9He/mw6iZAzoR2rrZQWL+J0/Bzdy3Mi5A4Knc mMbiQEXCszn8Q== From: SJ Park To: Andrew Morton Cc: Donggeun Yoo , stable@vger.kernel.org, SJ Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 1/2] mm/damon/core: charge only the part of a region the filter left Date: Mon, 21 Sep 2026 08:24:41 -0700 Message-ID: <20260921152443.80132-2-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260921152443.80132-1-sj@kernel.org> References: <20260921152443.80132-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Donggeun Yoo An address range DAMOS filter that partially overlaps a monitoring region splits the region at the filter boundary, so the scheme action is applied to only one side of it. damos_apply_scheme() reads the region size once on entry, before damos_core_filter_out() performs that split. The quota charge and the statistics update therefore account for the region as it was before the trim. schemes//stats/sz_tried counts memory the filter excluded, which Documentation/mm/damon/design.rst says is not counted as tried, and with quotas/bytes set the excluded part is charged against the budget, throttling the scheme to a fraction of what was configured. User impact is that DAMOS could unexpectedly slowly run, due to over-charged quota. DAMOS stat could also be confusing. No critical events such as crashes or leask happen. Re-read the region size after the core filters have run. Fixes: ab9bda001b68 ("mm/damon/core: introduce address range type damos fil= ter") Cc: # 6.6.x Signed-off-by: Donggeun Yoo Reviewee-by: SJ Park Signed-off-by: SJ Park --- mm/damon/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 0aa5d0ea8ebc..4687b909d42c 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2784,6 +2784,7 @@ static void damos_apply_scheme(struct damon_ctx *c, s= truct damon_target *t, } if (damos_core_filter_out(c, t, r, s)) return; + sz =3D damon_sz_region(r); ktime_get_coarse_ts64(&begin); trace_damos_before_apply(cidx, sidx, tidx, r, nr_accesses, damon_nr_regions(t), do_trace); --=20 2.47.3 From nobody Thu Sep 24 18:38:14 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 008F04BA1E6; Mon, 21 Sep 2026 15:24:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790004296; cv=none; b=r0q0LbHGjY2N8Q2wl2xEenaAu/26gGKmKRwy4uxYVramrWmKxxLYvyeCl7pamb95Qj246p74atV2jXHRzxHd1I5e+OIiPuWk2pCDZ06JBNc7DDbk4o2GFWHSnnt7L6pznhqfpgmg5oZmt0bNsYtFPzjq4+7pRE0w2PM0HMk5GCU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790004296; c=relaxed/simple; bh=Ijg/sok1QmpbNihkHPB+mOjzI7rWudnAZNFQv3ggtbc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oq/1K9cHBXcT86Wxqkhew2ciZbCPV5VMu+ExjLGC5JP6wodRHutGXipINwEFpFVMI8D4OPxe+Ig+euCeZTYUIKPik2ySIT4FimZJXp+ZfOR3PT78xC4rcmNQcVXUoQcJ0jio+t9PqmBO6JMI624auLfl8yPkjgHUcszrBl/bWd8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LkxD8AWZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LkxD8AWZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79B731F000FF; Mon, 21 Sep 2026 15:24:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790004294; bh=ZLvkpkC88KAc9pc9JRn5s2cgjSsFH8QP7LkU/PCNgfk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LkxD8AWZ5YFBPNXU57iAJXfnShcYu/TRlKkNQ4e+kNk6g9E3QI9iM2eVSjROcIc0r QJQ7+7r9FfwISjC1PBhu9/8NZBQtxdCmDI8Vt3b8iEYf8pMNEjwtY6h3kveojh5dng CEevjvcHdVSZwSF/+NiMdKjyxVAHF3DHkFJh2qyWSyDyymbtiA1ux8ULAeeMhK5Qes LvvlM/4cBBnyH7BhL4yxVGBYsTdZPmUomFlluXxTUWxfyWVyWN8wYOf9V2vBQDLSdJ 9HHGevnwAIuIXUju57TeSmrQqTuSMmhLBRtwJ2J654U0WLj9C9EYIbUpiW+AUCSxz8 PTG8S4Tg2k1aw== From: SJ Park To: Andrew Morton Cc: Donggeun Yoo , Brendan Higgins , David Gow , SJ Park , damon@lists.linux.dev, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 2/2] mm/damon/tests/core-kunit: test the size charged for a filter-trimmed region Date: Mon, 21 Sep 2026 08:24:42 -0700 Message-ID: <20260921152443.80132-3-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260921152443.80132-1-sj@kernel.org> References: <20260921152443.80132-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Donggeun Yoo damos_test_filter_out() checks that an address range filter splits a region at the filter boundary, and stops there. Nothing checks what damos_apply_scheme() then charges to the quota and reports as tried. damos_test_apply_scheme_filtered_sz() covers the two ways such a filter trims a region: one that starts before the filter's range, and one that starts inside it. damos_test_apply_scheme_filter_sz_unchanged() and damos_test_apply_scheme_quota_sz() cover the cases whose accounting must not change: a region wholly inside a reject range, one wholly inside an allow range, two filters trimming in a single call, a filter type that never splits, no filter at all, a region the quota trims, and a quota remainder too small for one region. Signed-off-by: Donggeun Yoo Reviewed-by: SJ Park Signed-off-by: SJ Park --- mm/damon/tests/core-kunit.h | 316 ++++++++++++++++++++++++++++++++++++ 1 file changed, 316 insertions(+) diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h index 5ff0436c5844..df84d9cc7d20 100644 --- a/mm/damon/tests/core-kunit.h +++ b/mm/damon/tests/core-kunit.h @@ -1706,6 +1706,319 @@ static void damos_test_filter_out(struct kunit *tes= t) damos_free_filter(f); } =20 +static unsigned long damos_test_apply_scheme_stub(struct damon_ctx *c, + struct damon_target *t, struct damon_region *r, + struct damos *s, unsigned long *sz_filter_passed) +{ + return 0; +} + +static void damos_test_apply_scheme_filtered_sz(struct kunit *test) +{ + struct damos_access_pattern pattern =3D { + .min_sz_region =3D 0, + .max_sz_region =3D ULONG_MAX, + .min_nr_accesses =3D 0, + .max_nr_accesses =3D UINT_MAX, + .min_age_region =3D 0, + .max_age_region =3D UINT_MAX, + }; + unsigned long min_sz =3D DAMON_MIN_REGION_SZ; + struct damos_watermarks wmarks =3D {}; + struct damos_quota quota =3D {}; + struct damon_ctx *c; + struct damon_target *t; + struct damon_region *r; + struct damos_filter *f; + struct damos *s; + + c =3D damon_new_ctx(); + if (!c) + kunit_skip(test, "ctx alloc fail"); + c->ops.apply_scheme =3D damos_test_apply_scheme_stub; + + s =3D damon_new_scheme(&pattern, DAMOS_STAT, 0, "a, &wmarks, + NUMA_NO_NODE); + if (!s) { + damon_destroy_ctx(c); + kunit_skip(test, "scheme alloc fail"); + } + damon_add_scheme(c, s); + + t =3D damon_new_target(); + if (!t) { + damon_destroy_ctx(c); + kunit_skip(test, "target alloc fail"); + } + damon_add_target(c, t); + + f =3D damos_new_filter(DAMOS_FILTER_TYPE_ADDR, true, false); + if (!f) { + damon_destroy_ctx(c); + kunit_skip(test, "filter alloc fail"); + } + f->addr_range =3D (struct damon_addr_range){ + .start =3D 2 * min_sz, + .end =3D 8 * min_sz + }; + damos_add_filter(s, f); + damos_set_filters_default_reject(s); + + /* reject filter, region starting before the range */ + r =3D damon_new_region(0, 4 * min_sz); + if (!r) { + damon_destroy_ctx(c); + kunit_skip(test, "region alloc fail"); + } + damon_add_region(r, t); + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 2); + KUNIT_EXPECT_EQ(test, r->ar.end, 2 * min_sz); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 2 * min_sz); + + if (damon_nr_regions(t) !=3D 2) + goto out; + damon_destroy_region(damon_next_region(r), t); + damon_destroy_region(r, t); + s->stat =3D (struct damos_stat){}; + + /* allow filter, region starting inside the range */ + f->allow =3D true; + damos_set_filters_default_reject(s); + r =3D damon_new_region(2 * min_sz, 10 * min_sz); + if (!r) { + damon_destroy_ctx(c); + kunit_skip(test, "region alloc fail"); + } + damon_add_region(r, t); + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 2); + KUNIT_EXPECT_EQ(test, r->ar.end, 8 * min_sz); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 6 * min_sz); + +out: + damon_destroy_ctx(c); +} + +static void damos_test_apply_scheme_filter_sz_unchanged(struct kunit *test) +{ + struct damos_access_pattern pattern =3D { + .min_sz_region =3D 0, + .max_sz_region =3D ULONG_MAX, + .min_nr_accesses =3D 0, + .max_nr_accesses =3D UINT_MAX, + .min_age_region =3D 0, + .max_age_region =3D UINT_MAX, + }; + unsigned long min_sz =3D DAMON_MIN_REGION_SZ; + struct damos_watermarks wmarks =3D {}; + struct damos_quota quota =3D {}; + struct damos_filter *f, *f2; + struct damon_ctx *c; + struct damon_target *t; + struct damon_region *r; + struct damos *s; + + c =3D damon_new_ctx(); + if (!c) + kunit_skip(test, "ctx alloc fail"); + c->ops.apply_scheme =3D damos_test_apply_scheme_stub; + + s =3D damon_new_scheme(&pattern, DAMOS_STAT, 0, "a, &wmarks, + NUMA_NO_NODE); + if (!s) { + damon_destroy_ctx(c); + kunit_skip(test, "scheme alloc fail"); + } + damon_add_scheme(c, s); + + t =3D damon_new_target(); + if (!t) { + damon_destroy_ctx(c); + kunit_skip(test, "target alloc fail"); + } + damon_add_target(c, t); + + f =3D damos_new_filter(DAMOS_FILTER_TYPE_ADDR, true, false); + if (!f) { + damon_destroy_ctx(c); + kunit_skip(test, "filter alloc fail"); + } + f->addr_range =3D (struct damon_addr_range){ + .start =3D 2 * min_sz, .end =3D 8 * min_sz}; + damos_add_filter(s, f); + damos_set_filters_default_reject(s); + + /* wholly inside a reject range: not counted at all */ + r =3D damon_new_region(4 * min_sz, 6 * min_sz); + if (!r) { + damon_destroy_ctx(c); + kunit_skip(test, "region alloc fail"); + } + damon_add_region(r, t); + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, s->stat.nr_tried, 0); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 0); + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); + + /* wholly inside an allow range: counted whole, not split */ + f->allow =3D true; + damos_set_filters_default_reject(s); + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 2 * min_sz); + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); + + /* two filters, each trimming: the size left after both is counted */ + damon_destroy_region(r, t); + s->stat =3D (struct damos_stat){}; + f->allow =3D false; + f->addr_range =3D (struct damon_addr_range){ + .start =3D 4 * min_sz, .end =3D 12 * min_sz}; + f2 =3D damos_new_filter(DAMOS_FILTER_TYPE_ADDR, true, false); + if (!f2) { + damon_destroy_ctx(c); + kunit_skip(test, "filter alloc fail"); + } + f2->addr_range =3D (struct damon_addr_range){ + .start =3D 2 * min_sz, .end =3D 3 * min_sz}; + damos_add_filter(s, f2); + damos_set_filters_default_reject(s); + + r =3D damon_new_region(0, 8 * min_sz); + if (!r) { + damon_destroy_ctx(c); + kunit_skip(test, "region alloc fail"); + } + damon_add_region(r, t); + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 3); + KUNIT_EXPECT_EQ(test, r->ar.end, 2 * min_sz); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 2 * min_sz); + + /* a core filter that never splits: counted whole */ + damos_destroy_filter(f2); + damos_destroy_filter(f); + f =3D damos_new_filter(DAMOS_FILTER_TYPE_TARGET, true, true); + if (!f) { + damon_destroy_ctx(c); + kunit_skip(test, "filter alloc fail"); + } + f->target_idx =3D 0; + damos_add_filter(s, f); + damos_set_filters_default_reject(s); + s->stat =3D (struct damos_stat){}; + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 3); + KUNIT_EXPECT_EQ(test, r->ar.end, 2 * min_sz); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 2 * min_sz); + + damon_destroy_ctx(c); +} + +static void damos_test_apply_scheme_quota_sz(struct kunit *test) +{ + struct damos_access_pattern pattern =3D { + .min_sz_region =3D 0, + .max_sz_region =3D ULONG_MAX, + .min_nr_accesses =3D 0, + .max_nr_accesses =3D UINT_MAX, + .min_age_region =3D 0, + .max_age_region =3D UINT_MAX, + }; + unsigned long min_sz =3D DAMON_MIN_REGION_SZ; + struct damos_watermarks wmarks =3D {}; + struct damos_quota quota =3D {}; + struct damon_region *r, *next; + struct damon_ctx *c; + struct damon_target *t; + struct damos *s; + + c =3D damon_new_ctx(); + if (!c) + kunit_skip(test, "ctx alloc fail"); + + s =3D damon_new_scheme(&pattern, DAMOS_STAT, 0, "a, &wmarks, + NUMA_NO_NODE); + if (!s) { + damon_destroy_ctx(c); + kunit_skip(test, "scheme alloc fail"); + } + damon_add_scheme(c, s); + damos_set_filters_default_reject(s); + + t =3D damon_new_target(); + if (!t) { + damon_destroy_ctx(c); + kunit_skip(test, "target alloc fail"); + } + damon_add_target(c, t); + + /* no apply_scheme operation: the whole region is counted */ + r =3D damon_new_region(0, 4 * min_sz); + if (!r) { + damon_destroy_ctx(c); + kunit_skip(test, "region alloc fail"); + } + damon_add_region(r, t); + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 4 * min_sz); + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); + + /* no filter and no quota: the whole region is counted */ + c->ops.apply_scheme =3D damos_test_apply_scheme_stub; + s->stat =3D (struct damos_stat){}; + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 4 * min_sz); + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); + + /* the quota trims the region: the trimmed size is counted */ + damon_for_each_region_safe(r, next, t) + damon_destroy_region(r, t); + s->stat =3D (struct damos_stat){}; + s->quota.esz =3D 2 * min_sz; + s->quota.charged_sz =3D 0; + + r =3D damon_new_region(0, 8 * min_sz); + if (!r) { + damon_destroy_ctx(c); + kunit_skip(test, "region alloc fail"); + } + damon_add_region(r, t); + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, r->ar.end, 2 * min_sz); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 2 * min_sz); + + /* quota remainder below one region: tried, but nothing counted */ + damon_for_each_region_safe(r, next, t) + damon_destroy_region(r, t); + s->stat =3D (struct damos_stat){}; + s->quota.esz =3D 1; + s->quota.charged_sz =3D 0; + + r =3D damon_new_region(0, 4 * min_sz); + if (!r) { + damon_destroy_ctx(c); + kunit_skip(test, "region alloc fail"); + } + damon_add_region(r, t); + + damos_apply_scheme(c, t, r, s); + KUNIT_EXPECT_EQ(test, s->stat.nr_tried, 1); + KUNIT_EXPECT_EQ(test, s->stat.sz_tried, 0); + KUNIT_EXPECT_EQ(test, r->ar.end, 4 * min_sz); + + damon_destroy_ctx(c); +} + static void damon_test_feed_loop_next_input(struct kunit *test) { unsigned long last_input =3D 900000, current_score =3D 200; @@ -1959,6 +2272,9 @@ static struct kunit_case damon_test_cases[] =3D { KUNIT_CASE(damon_test_commit_ctx), KUNIT_CASE(damon_test_valid_probe_params), KUNIT_CASE(damos_test_filter_out), + KUNIT_CASE(damos_test_apply_scheme_filtered_sz), + KUNIT_CASE(damos_test_apply_scheme_filter_sz_unchanged), + KUNIT_CASE(damos_test_apply_scheme_quota_sz), KUNIT_CASE(damon_test_feed_loop_next_input), KUNIT_CASE(damon_test_set_filters_default_reject), KUNIT_CASE(damon_test_apply_min_nr_regions), --=20 2.47.3