From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f198.google.com (mail-pf1-f198.google.com [209.85.210.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D26939BFEF for ; Tue, 1 Sep 2026 05:22:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788240176; cv=none; b=n+wB1Dbx8/iubQjT4SsLs6a2tboxMO6J4qaicHqUoDXWaDnPdpV/UBr4QgDwauBab+MNSaI45TjkVyaAsLoRFx0qFbRuPEzW/DWZF2R0aS47PRw7oIOFkffGjGqWmZhPqxhHH0Gyrfsidcgt3FHbJZmyqytOksP7dYaD+4HwuhY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788240176; c=relaxed/simple; bh=LKe2bNctC1A/j7uhC7WkmhcWVRTU9Foz1HcENo/uvJ0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=gcNKvH5cVcq2+k8PKZlwB1Bn/nW2GZG73ERlt93IynIve+DG+4ZkVkuF9+nLj74C5PD2Yelxdyjah5bTd/24tbGKzsJtbrHPNmd7knkpJKvkeI/ZGqbdD9wXGBxn+wTCfY7U5plsXJWj5zgusmgzx0n0NE6A7LyintwSd/T2AHQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--wfelipe.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=NnEZ5/P5; arc=none smtp.client-ip=209.85.210.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--wfelipe.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="NnEZ5/P5" Received: by mail-pf1-f198.google.com with SMTP id d2e1a72fcca58-854f274dd69so732429b3a.1 for ; Mon, 31 Aug 2026 22:22:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1788240175; x=1788844975; darn=vger.kernel.org; h=content-transfer-encoding:content-type:cc:to:from:subject :message-id:references:mime-version:in-reply-to:date:from:to:cc :subject:date:message-id:reply-to:content-type; bh=txHyoP6V8LSeV3HcUyvKh0AUgxf1/LIju6BYMJo/v9M=; b=NnEZ5/P5Lc0Zm0nGY8zofUcATHpHcV3LEkf0cGfgqNmVw/KIfXg6roswR6M4/NEhVG HeoQFuqtyvoIpsizNV9NOB5gP4FNbMKkdY/5EEkpQMxjNI6dOr55kJoZw8jvSurbf962 XU0r4W+xSCwV81wHeVL0h8v5FNO79ONUGdV4dPjf4QEytX2gUX9WEqmGEHCRCrXHUw+j r9M7q60AVqPQ+TtY+aDF6E2dDN+WJHuOMD5dl8uIoexnX6YeEDVxueA6yJWqhQ495BKo lTpkVF20S7KoUx7MeGM1oot9c2BqLZ9no8KWOu2iNc60eq4VXJ+Xm9GlUdF5Np3JQdzH DX6A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788240175; x=1788844975; h=content-transfer-encoding:content-type:cc:to:from:subject :message-id:references:mime-version:in-reply-to:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=txHyoP6V8LSeV3HcUyvKh0AUgxf1/LIju6BYMJo/v9M=; b=E0Ps2/vZdVH14MFB7BokCNQ6glVBdIrMu3elR4NSgcxj7jTf5r7qacgC7uD4dfOHgZ Z8wDdu4Ue35HZLIX2LZ08y+sn9umUq0LYx9tYSsoaIoesaqHbY1POIbd5B/TFX9kp3lN gsZrRGYUQcYYQ4KQBnewwVBMMWEL25uK7xJU31RqK+/+2d9XkzTDaxfmik3VyYX+M9dk MFQiIq4HaHw9DJBcq0MkWF7e340m9hHgWJ8A6fj72h4sycbMN/jdbSkRB5KoeqJ530Oj J8AQJDbRl7xH0MVSJBMal93Wsnb0KdoAGdXsezR32gaCb73I/vxpCHLibjxmpFhMEj07 qC+w== X-Forwarded-Encrypted: i=1; AHgh+Rpc84U9FILqoTAfbL+9jQAf6zoIaPxygu3oxlr1qhGa/AO8RA30gYnhtX4ymu++i7N5x4HpbiMRTrYxzWZ1z10=@vger.kernel.org X-Gm-Message-State: AFuF++mJ2YJ3m+t21Epn3nGxjsdZdxSXXgip39MwsTWyMOFUGzSVDtDd KPDq83P957j5CTIXB9XWc1aN96UsQ+ZFy/M9FThglz+954Ut83iQct0MUYl6tWk55AVUTeKGjYE nBNeW2AwQhg== X-Received: from pfbfh35.prod.google.com ([2002:a05:6a00:3923:b0:847:a85b:6c23]) (user=wfelipe job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:3692:b0:848:5f4f:289d with SMTP id d2e1a72fcca58-856277dba33mr51581983b3a.4.1788240174518; Mon, 31 Aug 2026 22:22:54 -0700 (PDT) Date: Tue, 1 Sep 2026 05:22:28 +0000 In-Reply-To: <20260901052250.154532-1-wfelipe@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260901052250.154532-1-wfelipe@google.com> X-Mailer: git-send-email 2.55.0.970.g62bdec98f9-goog Message-ID: <20260901052250.154532-3-wfelipe@google.com> Subject: [PATCH v5 2/2] selftests/cgroup: test_zswap: fix implicit unsigned promotion bug in test_no_kmem_bypass From: Wilson Felipe Pereira To: Andrew Morton , Johannes Weiner , Yosry Ahmed , Nhat Pham , Chengming Zhou , Tejun Heo , "=?UTF-8?q?Michal=20Koutn=C3=BD?=" , Shuah Khan Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Wilson Felipe Pereira Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable In test_no_kmem_bypass(), delta (stored_pages * page_size - zswapped) is checked against stored_pages * page_size / 4 to verify that the pages pushed to zswap belong to the test memory cgroup. Due to slight stat update timing differences, delta can evaluate to a small negative number (e.g. -5MB out of 1GB). Because delta is declared as a signed int and stored_pages is an unsigned size_t, C's usual arithmetic conversions implicitly promote a negative delta to a large unsigned 64-bit integer, causing `delta < stored_pages * page_size / 4` to falsely evaluate to 0 and fail the test. Fix this by declaring zswapped and delta as signed long long and comparing against a signed threshold, ensuring negative deltas correctly evaluate to true. Fixes: a549f9f31561a ("selftests: cgroup: add test_zswap with no kmem bypas= s test") Signed-off-by: Wilson Felipe Pereira Acked-by: Michal Koutn=C3=BD --- tools/testing/selftests/cgroup/lib/cgroup_util.c | 9 +++++++-- .../selftests/cgroup/lib/include/cgroup_util.h | 1 + tools/testing/selftests/cgroup/test_zswap.c | 13 ++++++++----- 3 files changed, 16 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/cgroup/lib/cgroup_util.c b/tools/testi= ng/selftests/cgroup/lib/cgroup_util.c index 2596c12cd864..ce2dd36291f8 100644 --- a/tools/testing/selftests/cgroup/lib/cgroup_util.c +++ b/tools/testing/selftests/cgroup/lib/cgroup_util.c @@ -172,7 +172,7 @@ long cg_read_long_fd(int fd) return atol(buf); } =20 -long cg_read_key_long(const char *cgroup, const char *control, const char = *key) +long long cg_read_key_long_long(const char *cgroup, const char *control, c= onst char *key) { char buf[BUF_SIZE]; char *ptr; @@ -184,7 +184,12 @@ long cg_read_key_long(const char *cgroup, const char *= control, const char *key) if (!ptr) return -1; =20 - return atol(ptr + strlen(key)); + return atoll(ptr + strlen(key)); +} + +long cg_read_key_long(const char *cgroup, const char *control, const char = *key) +{ + return (long)cg_read_key_long_long(cgroup, control, key); } =20 long cg_read_key_long_poll(const char *cgroup, const char *control, diff --git a/tools/testing/selftests/cgroup/lib/include/cgroup_util.h b/too= ls/testing/selftests/cgroup/lib/include/cgroup_util.h index 5d39c709ac7a..13923534003c 100644 --- a/tools/testing/selftests/cgroup/lib/include/cgroup_util.h +++ b/tools/testing/selftests/cgroup/lib/include/cgroup_util.h @@ -69,6 +69,7 @@ extern int cg_read_strstr(const char *cgroup, const char = *control, const char *needle); extern long cg_read_long(const char *cgroup, const char *control); extern long cg_read_long_fd(int fd); +long long cg_read_key_long_long(const char *cgroup, const char *control, c= onst char *key); long cg_read_key_long(const char *cgroup, const char *control, const char = *key); long cg_read_key_long_poll(const char *cgroup, const char *control, const char *key, long expected, int retries, diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/se= lftests/cgroup/test_zswap.c index 8f2c9aa4776c..11c67dde705f 100644 --- a/tools/testing/selftests/cgroup/test_zswap.c +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -630,11 +630,14 @@ static int test_no_kmem_bypass(const char *root) break; /* If memory was pushed to zswap, verify it belongs to memcg */ if (stored_pages > stored_pages_threshold) { - int zswapped =3D cg_read_key_long(test_group, "memory.stat", "zswapped = "); - int delta =3D stored_pages * page_size - zswapped; - int result_ok =3D delta < stored_pages * page_size / 4; - - ret =3D result_ok ? KSFT_PASS : KSFT_FAIL; + long long zswapped =3D cg_read_key_long_long( + test_group, "memory.stat", "zswapped "); + long long delta =3D + (long long)stored_pages * page_size - zswapped; + long long max_delta =3D + (long long)stored_pages * page_size / 4; + + ret =3D (delta < max_delta) ? KSFT_PASS : KSFT_FAIL; break; } } --=20 2.55.0.970.g62bdec98f9-goog