From mboxrd@z Thu Jan 1 00:00:00 1970 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 4F89E503BE0 for ; Tue, 29 Sep 2026 12:10:27 +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=1790683833; cv=none; b=o0G28X31zyevTNN7Cy7/DpBaKX3va0haiW3dMu4MhrOUY7mxBqPxHv6GBS40Fdd17P1Z4hFGA14tTQI2YruRwQeeQbgwQgdA5AajcAxOG+WCnCSKNx1GApJdTHegG345arX6/B9Yy6yCj7cWTiU9eEey2mriCBb7hDyTX2V4t3w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790683833; c=relaxed/simple; bh=xTlLcDlJd4gC0PI83WFZi90s8iRLyUj7rwuoQQPmRUY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HXJRr0SDN7gWrVb1G8tH8iQDUKsPOcxfNuCQlytZ42qHx2Ee3CDHKCuocPEMCMa7y1t5stzkvHvbreZ/0rMRYDRS/tTraFpOko49sqH7inkF4lHnX+ik/mv6AexbONwnmilPlNaD0EkRXTHVj59xafGMdNDv44U8yBTqNMVJJNU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UpPHJU92; 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="UpPHJU92" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B67D51F0089A; Tue, 29 Sep 2026 12:10:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790683824; bh=OEH/ZxS2zah0MypDyhKJppv566Bu9su1vO57zJjRsEo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UpPHJU92ZZQqic3dfw8bl/a04ENFpnvUjkr6MAyvHFPj9DcYEyet1Ax70TAwXBQoT Xj6fONY2R8e0tOeAkpuxstrrde33pDihuWydXITTod5WQ+KHtE6Vtc8ZE8GVDpciKL vyabY7+jfb7WPYYhxo77a2A6DBlRr0QK6qwl16vzti6Vep5Cgbb9KgOSffeUkIh1J/ glT/Criz0oDQ2G2nr0AKCz9wMwhX36vhDJ9aFIVGjvbWtnkpojfxXM8c8RSi75h2Y1 +LOBj3UjFgdw2CqCvCR9yRRi+u/8W++dtaWS4XyXOrMrQPUmzHSJPo+aRHIqdzq81I PHVYQPygTdFoA== From: Sasha Levin To: stable@vger.kernel.org Cc: Hui Peng , Guopeng Zhang , Waiman Long , Tejun Heo , Sasha Levin Subject: [PATCH 6.18.y 3/3] cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict Date: Tue, 29 Sep 2026 08:10:20 -0400 Message-ID: <20260929121020.3306361-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260929121020.3306361-1-sashal@kernel.org> References: <2026092918-captive-docile-ef46@gregkh> <20260929121020.3306361-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Hui Peng [ Upstream commit 31c88350b7dd1522792f726f79607f31bb55c50f ] When a remote partition is created underneath an existing local partition via a non-partition (PRS_MEMBER) intermediate cgroup, update_prstate() sees parent->partition_root_state == PRS_MEMBER and calls remote_partition_enable(). Commit 86888c7bd117 ("cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs") replaced the cpumask_intersects(tmp->new_cpus, subpartitions_cpus) error check in remote_partition_enable() with WARN_ON_ONCE(). As a result, remote_partition_enable() emits a warning and proceeds to enable the remote partition on CPUs that are already owned by the ancestor local partition in subpartitions_cpus. This can be reproduced on Linux 7.3.0-rc3 with: mkdir -p /tmp/cg1 mount -t cgroup2 none /tmp/cg1 echo "+cpuset" > /tmp/cg1/cgroup.subtree_control mkdir /tmp/cg1/A echo 1 > /tmp/cg1/A/cpuset.cpus echo 1 > /tmp/cg1/A/cpuset.cpus.exclusive echo root > /tmp/cg1/A/cpuset.cpus.partition echo "+cpuset" > /tmp/cg1/A/cgroup.subtree_control mkdir /tmp/cg1/A/B echo 1 > /tmp/cg1/A/B/cpuset.cpus echo 1 > /tmp/cg1/A/B/cpuset.cpus.exclusive echo "+cpuset" > /tmp/cg1/A/B/cgroup.subtree_control mkdir /tmp/cg1/A/B/D echo 1 > /tmp/cg1/A/B/D/cpuset.cpus echo 1 > /tmp/cg1/A/B/D/cpuset.cpus.exclusive echo root > /tmp/cg1/A/B/D/cpuset.cpus.partition which triggers: WARNING: kernel/cgroup/cpuset.c:1594 at remote_partition_enable+0x1c1/0x300 and leaves both /tmp/cg1/A and /tmp/cg1/A/B/D as active root partitions claiming exclusive CPU 1. Fix this by returning PERR_NOCPUS when tmp->new_cpus intersects subpartitions_cpus in remote_partition_enable(), matching the error code used by remote_cpus_update() for the same subpartitions_cpus conflict, and add a regression test case to tools/testing/selftests/cgroup/test_cpuset_prs.sh. Tested in QEMU on Linux 7.3.0-rc3 using the reproducer above and tools/testing/selftests/cgroup/test_cpuset_prs.sh. Fixes: 86888c7bd117 ("cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs") Suggested-by: Guopeng Zhang Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hui Peng Reviewed-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin --- kernel/cgroup/cpuset.c | 3 ++- tools/testing/selftests/cgroup/test_cpuset_prs.sh | 2 ++ 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 17d4ef96794c1..eebbede820700 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1623,10 +1623,11 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs, * above it or remote partition root underneath it is not allowed. */ compute_excpus(cs, tmp->new_cpus); - WARN_ON_ONCE(cpumask_intersects(tmp->new_cpus, subpartitions_cpus)); if (!cpumask_intersects(tmp->new_cpus, cpu_active_mask) || cpumask_subset(top_cpuset.effective_cpus, tmp->new_cpus)) return PERR_INVCPUS; + if (cpumask_intersects(tmp->new_cpus, subpartitions_cpus)) + return PERR_NOCPUS; if (((new_prs == PRS_ISOLATED) && !isolated_cpus_can_update(tmp->new_cpus, NULL)) || prstate_housekeeping_conflict(new_prs, tmp->new_cpus)) diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/testing/selftests/cgroup/test_cpuset_prs.sh index 592e533cd4d7b..6f7e387f68e5b 100755 --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh @@ -297,6 +297,8 @@ TEST_MATRIX=( " C0-4:X2-4:S+ C1-4:X2-4:S+:P2 C2-4:X4:P1 \ . . . X1 . 0 A1:0-1|A2:2-4|A3:2-4 \ A1:P0|A2:P2|A3:P-1 2-4" + " CX1-3:P1 CX1-3 CX1-3 . . . P1 . 0 A1:1-3|A2:1-3|A3:1-3 \ + A1:P1|A2:P0|A3:P-1" # Remote partition offline tests " C0-3:S+ C1-3:S+ C2-3 . X2-3 X2-3 X2-3:P2:O2=0 . 0 A1:0-1|A2:1|A3:3 A1:P0|A3:P2 2-3" -- 2.53.0