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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 26 Mar 2019 23:13:16 -0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2QNDFEi14418102 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 26 Mar 2019 23:13:15 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C402AB207A; Tue, 26 Mar 2019 23:13:14 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A67DAB2071; Tue, 26 Mar 2019 23:13:14 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.188]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 26 Mar 2019 23:13:14 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 88DF116C42B1; Tue, 26 Mar 2019 16:13:15 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 10/18] rcu: Report error for bad rcu_nocbs= parameter values Date: Tue, 26 Mar 2019 16:13:06 -0700 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190326231253.GA18343@linux.ibm.com> References: <20190326231253.GA18343@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 19032623-0068-0000-0000-000003AB749F X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010820; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000282; SDB=6.01180132; UDB=6.00617573; IPR=6.00960848; MB=3.00026169; MTD=3.00000008; XFM=3.00000015; UTC=2019-03-26 23:13:20 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19032623-0069-0000-0000-000047F21E39 Message-Id: <20190326231314.19518-10-paulmck@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-26_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=13 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903260156 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This commit prints a console message when cpulist_parse() reports a bad list of CPUs, and sets all CPUs' bits in that case. The reason for setting all CPUs' bits is that this is the safe(r) choice for real-time workloads, which would normally be the ones using the rcu_nocbs= kernel boot parameter. Either way, later RCU console log messages list the actual set of CPUs whose RCU callbacks will be offloaded. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_plugin.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index ed4a6dabf31d..f0aeb7416dcc 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1772,14 +1772,22 @@ static void zero_cpu_stall_ticks(struct rcu_data *rdp) */ -/* Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters. */ +/* + * Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters. + * The string after the "rcu_nocbs=" is either "all" for all CPUs, or a + * comma-separated list of CPUs and/or CPU ranges. If an invalid list is + * given, a warning is emitted and all CPUs are offloaded. + */ static int __init rcu_nocb_setup(char *str) { alloc_bootmem_cpumask_var(&rcu_nocb_mask); if (!strcasecmp(str, "all")) cpumask_setall(rcu_nocb_mask); else - cpulist_parse(str, rcu_nocb_mask); + if (cpulist_parse(str, rcu_nocb_mask)) { + pr_warn("rcu_nocbs= bad CPU range, all CPUs set\n"); + cpumask_setall(rcu_nocb_mask); + } return 1; } __setup("rcu_nocbs=", rcu_nocb_setup); -- 2.17.1