From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794590890; b=Cvt3LclqVpBhd/DJqbZUpN/J5j23U6YZw5GMWmlNDIJ9qp7oTaFXlpPhvME0Wt9qK7yp irNgypg7CKGz6/8r9xcsGFlL0idODtog+lPD2VdegDTTQ7s78efLGRytm519gy4p5CRn+ YWdl7yXXvsa6NsaaiOUfJ6jR4zfeQn3PYHPOeDF0TTFhZzxuwZd1c8V00DDhubpMEz002 HMpLDRYQy5aseCHgdc6UQP5uwLozTui6JBNJ8ZHHGdSwdQH2vDxa7N6uE5iFSVLMk/TLX I91qt+atUjOEL6wK75ej9PqcGZSgAclt4JPQ6swRFX6mSJQC93msoQd4La+2C9iNQYA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794590890; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=+TPyUzrZ6qHAmRRXQfCisspaxBZGjnpsWO8lZ1OtvmM=; b=MY4iwqb95byi1K8BS1R+YG8YJgcG0MWaKXap3UXYtano+zDp7xNKgrskdXdJ3Biwwqbw +Y3CXyTxjY7euP+/AfpMclc/VAuHM0H4/wQBq+imQ20kFv6m/P1fIa40odSjMhz7dCflB L+7sFNS6dVlr0tfR98emRoZf5gP4MzaSdxv3GHhtPD7RD0XZZqxg3d8BBgasd/zu/P01D 5asU8d9OvLi3LYLGl1ly0/YBn5n5im41VyL/f2YX2rvYecir5Mm71p4jFD/OTbQ6YD6pB XB2ZDK68Tbn1I6pdrK34o4RFUiDrlz1HoSZRIolBMmKmVpyRgYfwvQz9iv7dS5MQ2Pg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=IxxOpL9W; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 30E04606E217; Fri, 13 Nov 2026 17:28:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=IxxOpL9W Received: by smtp.kernel.org (Postfix) with ESMTPSA id D14721F000C4; Fri, 13 Nov 2026 17:28:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794590890; bh=+TPyUzrZ6qHAmRRXQfCisspaxBZGjnpsWO8lZ1OtvmM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IxxOpL9WRuvA7jrEUM3/u9QWeRr6PioNBU6qfchQmaoP1kMNL4MNIcISesfdBIGdg 01TsXIXZ0Iy08XQoahcKUPXhcN2gF29Pox/PXfKEaj/Yvfr/Bwekz7H2898c3F9YrJ mfTX1/YMCU69XlzvkO4UH5WZnRJJT2PVNP+JvNKM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, SJ Park , Andrew Morton , Sasha Levin Subject: [PATCH 6.12 082/670] mm/damon/core: filter out damos address filter-split failed region Date: Fri, 13 Nov 2026 10:44:06 -0500 Message-ID: <20261113153814.566679208@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153811.177190860@linuxfoundation.org> References: <20261113153811.177190860@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: SJ Park [ Upstream commit bbeec2d8324d7aac438bb12dd2d22b184e0a8d43 ] When an address type DAMOS filter is configured, DAMOS tries to split the region for the filter range, and apply DAMOS action to the filter-in region. The split operation (damon_split_region_at()) could fail from allocation failure under extreme memory pressure. In the case, DAMOS action could be applied more or less than expected, ignoring the address filter. The issue only rarely happens under extreme memory pressure. No crash or leak happens. Occasionally not applying the action to a few regions shouldn't be a real problem. But applying the action to a region that the user has excluded via address filter could be a surprise depending on the use case. It is only theoretical. No such real case is found yet. Filter out the entire region if the split is failed. Update damos_filter_match() signature to receive the error from split. Also update kunit tests for the updated signature. The issue was discovered [1] by sashiko. Link: https://lore.kernel.org/20261020004119.106690-1-sj@kernel.org Link: https://lore.kernel.org/20260801203121.117449-1-sj@kernel.org [1] Fixes: ab9bda001b68 ("mm/damon/core: introduce address range type damos filter") Signed-off-by: SJ Park Signed-off-by: Andrew Morton Cc: # 6.6.x Signed-off-by: SJ Park Signed-off-by: Sasha Levin --- mm/damon/core.c | 13 +++++++++---- mm/damon/tests/core-kunit.h | 11 ++++++----- 2 files changed, 15 insertions(+), 9 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 200cadceed148..7e64b2959bd01 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -1377,13 +1377,14 @@ static void damos_update_stat(struct damos *s, } static bool __damos_filter_out(struct damon_ctx *ctx, struct damon_target *t, - struct damon_region *r, struct damos_filter *filter) + struct damon_region *r, struct damos_filter *filter, int *err) { bool matched = false; struct damon_target *ti; int target_idx = 0; unsigned long start, end; + *err = 0; switch (filter->type) { case DAMOS_FILTER_TYPE_TARGET: damon_for_each_target(ti, ctx) { @@ -1409,12 +1410,13 @@ static bool __damos_filter_out(struct damon_ctx *ctx, struct damon_target *t, } /* start before the range and overlap */ if (r->ar.start < start) { - damon_split_region_at(t, r, start - r->ar.start); + *err = damon_split_region_at(t, r, + start - r->ar.start); matched = false; break; } /* start inside the range */ - damon_split_region_at(t, r, end - r->ar.start); + *err = damon_split_region_at(t, r, end - r->ar.start); matched = true; break; default: @@ -1428,9 +1430,12 @@ static bool damos_filter_out(struct damon_ctx *ctx, struct damon_target *t, struct damon_region *r, struct damos *s) { struct damos_filter *filter; + bool matching; + int err; damos_for_each_filter(filter, s) { - if (__damos_filter_out(ctx, t, r, filter)) + matching = __damos_filter_out(ctx, t, r, filter, &err); + if (matching || err) return true; } return false; diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h index ff9f73579f7b3..6b7cd8149a0e2 100644 --- a/mm/damon/tests/core-kunit.h +++ b/mm/damon/tests/core-kunit.h @@ -527,6 +527,7 @@ static void damos_test_filter_out(struct kunit *test) struct damon_target *t; struct damon_region *r, *r2; struct damos_filter *f; + int err; f = damos_new_filter(DAMOS_FILTER_TYPE_ADDR, true); f->addr_range = (struct damon_addr_range){ @@ -537,25 +538,25 @@ static void damos_test_filter_out(struct kunit *test) damon_add_region(r, t); /* region in the range */ - KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f, &err)); KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); /* region before the range */ r->ar.start = DAMON_MIN_REGION * 1; r->ar.end = DAMON_MIN_REGION * 2; - KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f, &err)); KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); /* region after the range */ r->ar.start = DAMON_MIN_REGION * 6; r->ar.end = DAMON_MIN_REGION * 8; - KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f, &err)); KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); /* region started before the range */ r->ar.start = DAMON_MIN_REGION * 1; r->ar.end = DAMON_MIN_REGION * 4; - KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f, &err)); /* filter should have split the region */ KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 1); KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 2); @@ -570,7 +571,7 @@ static void damos_test_filter_out(struct kunit *test) /* region started in the range */ r->ar.start = DAMON_MIN_REGION * 2; r->ar.end = DAMON_MIN_REGION * 8; - KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f, &err)); /* filter should have split the region */ KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 2); KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 6); -- 2.53.0