From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751773AbdJUHKl (ORCPT ); Sat, 21 Oct 2017 03:10:41 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:53744 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751187AbdJUHKk (ORCPT ); Sat, 21 Oct 2017 03:10:40 -0400 X-Google-Smtp-Source: ABhQp+R2Q6zkIHosxtshY2C8WKmyuc2QM4V4slFCWMTabHYN2DiftlERxamidIsa9D12ZzVgascNmw== From: Rakib Mullick To: mingo@kernel.org Cc: peterz@infradead.org, mka@chromium.org, longman@redhat.com, adobriyan@gmail.com, tglx@linutronix.de, akpm@linux-foundation.org, tj@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] Fix isocpus's param handling when CPUMASK_OFFSTACK=n. Date: Sat, 21 Oct 2017 13:10:17 +0600 Message-Id: <20171021071017.10554-1-rakib.mullick@gmail.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20171020084939.r6ox4o7k2kgezzbk@gmail.com> References: <20171020084939.r6ox4o7k2kgezzbk@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > *On Fri, Oct 20, 2017 at 2:49 PM, Ingo Molnar wrote: > >> Rakib Mullick wrote: >> include/linux/cpumask.h | 16 ++++++++++++++++ >> kernel/sched/topology.c | 8 +++++--- >> 2 files changed, 21 insertions(+), 3 deletions(-) > > What kernel is this against? It does not apply to the latest kernels. It was against 4.14-rc4, prepared before -rc5 release. Please, consider the below one, against -rc5. cpulist_parse() uses nr_cpumask_bits as limit to parse the passed buffer from kernel commandline. What nr_cpumask_bits represents varies depends upon CONFIG_CPUMASK_OFFSTACK option. If CONFIG_CPUMASK_OFFSTACK=n, then nr_cpumask_bits is same as NR_CPUS, which might not represent the # of cpus really exist (default 64). So, there's a chance of gap between nr_cpu_ids and NR_CPUS, which ultimately lead towards invalid cpulist_parse() operation. For example, if isolcpus=9 is passed on a 8 cpu system (CONFIG_CPUMASK_OFFSTACK=n) it doesn't show the error that it suppose to. This patch fixes this issue by effectively find out the last cpu of the passed isolcpus list and checking it with nr_cpu_ids. Also, fixes the error message where the nr_cpu_ids should be nr_cpu_ids-1, since the cpu numbering starts from 0. Signed-off-by: Rakib Mullick --- include/linux/cpumask.h | 16 ++++++++++++++++ kernel/sched/topology.c | 8 +++++--- 2 files changed, 21 insertions(+), 3 deletions(-) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index cd415b7..5631725 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -130,6 +130,11 @@ static inline unsigned int cpumask_first(const struct cpumask *srcp) return 0; } +static inline unsigned int cpumask_last(const struct cpumask *srcp) +{ + return 0; +} + /* Valid inputs for n are -1 and 0. */ static inline unsigned int cpumask_next(int n, const struct cpumask *srcp) { @@ -178,6 +183,17 @@ static inline unsigned int cpumask_first(const struct cpumask *srcp) return find_first_bit(cpumask_bits(srcp), nr_cpumask_bits); } +/** + * cpumask_last - get the last cpu in a cpumask + * @srcp: - the cpumask pointer + * + * Returns >= nr_cpumask_bits if no cpus set. + */ +static inline unsigned int cpumask_last(const struct cpumask *srcp) +{ + return find_last_bit(cpumask_bits(srcp), nr_cpumask_bits); +} + unsigned int cpumask_next(int n, const struct cpumask *srcp); /** diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index f1cf4f3..b9265c8 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -466,12 +466,14 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) /* Setup the mask of CPUs configured for isolated domains */ static int __init isolated_cpu_setup(char *str) { - int ret; + int ret, lastcpu; alloc_bootmem_cpumask_var(&cpu_isolated_map); ret = cpulist_parse(str, cpu_isolated_map); - if (ret) { - pr_err("sched: Error, all isolcpus= values must be between 0 and %u\n", nr_cpu_ids); + lastcpu = cpumask_last(cpu_isolated_map); + if (ret || lastcpu >= nr_cpu_ids) { + pr_err("sched: Error, all isolcpus= values must be between 0 and %u\n", + nr_cpu_ids-1); return 0; } return 1; -- 2.9.3