From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9FA2E2C9C for ; Tue, 7 Feb 2023 13:05:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F8D4C433B0; Tue, 7 Feb 2023 13:05:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1675775125; bh=YtQGz6Qkk7Rhtb13J/VzPJf5PK5xPLZhaeoyma7KvbA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z9ZLwXD/XppcDnVT2DcT1q+ERoypvw5tTNhUURcaFVpXCy6O6jtx0+ZF+z+4VMsOx Zisjq9Q8RO1HTdGH1Nii0DP0bErEJzExziiHtQ9suCDdeGtnFpOryXwvXFWVuUUqH7 7h0tyVcSAdAzCJC2CYVudg9FhizCvOYfe0w3g/WQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Srinivas Pandruvada , Waiman Long , Tejun Heo Subject: [PATCH 6.1 116/208] cgroup/cpuset: Fix wrong check in update_parent_subparts_cpumask() Date: Tue, 7 Feb 2023 13:56:10 +0100 Message-Id: <20230207125639.646526721@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230207125634.292109991@linuxfoundation.org> References: <20230207125634.292109991@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Waiman Long commit e5ae8803847b80fe9d744a3174abe2b7bfed222a upstream. It was found that the check to see if a partition could use up all the cpus from the parent cpuset in update_parent_subparts_cpumask() was incorrect. As a result, it is possible to leave parent with no effective cpu left even if there are tasks in the parent cpuset. This can lead to system panic as reported in [1]. Fix this probem by updating the check to fail the enabling the partition if parent's effective_cpus is a subset of the child's cpus_allowed. Also record the error code when an error happens in update_prstate() and add a test case where parent partition and child have the same cpu list and parent has task. Enabling partition in the child will fail in this case. [1] https://www.spinics.net/lists/cgroups/msg36254.html Fixes: f0af1bfc27b5 ("cgroup/cpuset: Relax constraints to partition & cpus changes") Cc: stable@vger.kernel.org # v6.1 Reported-by: Srinivas Pandruvada Signed-off-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup/cpuset.c | 3 ++- tools/testing/selftests/cgroup/test_cpuset_prs.sh | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1342,7 +1342,7 @@ static int update_parent_subparts_cpumas * A parent can be left with no CPU as long as there is no * task directly associated with the parent partition. */ - if (!cpumask_intersects(cs->cpus_allowed, parent->effective_cpus) && + if (cpumask_subset(parent->effective_cpus, cs->cpus_allowed) && partition_is_populated(parent, cs)) return PERR_NOCPUS; @@ -2320,6 +2320,7 @@ out: new_prs = -new_prs; spin_lock_irq(&callback_lock); cs->partition_root_state = new_prs; + WRITE_ONCE(cs->prs_err, err); spin_unlock_irq(&callback_lock); /* * Update child cpusets, if present. --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh @@ -254,6 +254,7 @@ TEST_MATRIX=( # Taking away all CPUs from parent or itself if there are tasks # will make the partition invalid. " S+ C2-3:P1:S+ C3:P1 . . T C2-3 . . 0 A1:2-3,A2:2-3 A1:P1,A2:P-1" + " S+ C3:P1:S+ C3 . . T P1 . . 0 A1:3,A2:3 A1:P1,A2:P-1" " S+ $SETUP_A123_PARTITIONS . T:C2-3 . . . 0 A1:2-3,A2:2-3,A3:3 A1:P1,A2:P-1,A3:P-1" " S+ $SETUP_A123_PARTITIONS . T:C2-3:C1-3 . . . 0 A1:1,A2:2,A3:3 A1:P1,A2:P1,A3:P1"