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Date: Mon, 13 Feb 2017 13:06:50 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Ingo Molnar <mingo@kernel.org>, linux-kernel@vger.kernel.org,
        guohanjun@huawei.com, Prarit Bhargava <prarit@redhat.com>
Subject: Re: [PATCH] sched/isolcpus: Show isolated cpu map
Message-ID: <20170213120650.GN6515@twins.programming.kicks-ass.net>
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On Mon, Feb 13, 2017 at 05:43:59PM +0800, Kefeng Wang wrote:
> The commit a6e4491c682a ("sched/isolcpus: Output warning when the
> 'isolcpus=' kernel parameter is invalid") adds an error message
> when specified cpu bigger than nr_cpu_ids, but nr_cpumask_bits in
> cpulist_parse() could be nr_cpu_ids or NR_CPUS.
> 
> eg, NR_CPUS=64, nr_cpu_ids=8 in ARM64, cpulist_parse() won't return
> -ERANGE if isolcpus=1-10;
> 

But why does cpulist_parse() use nr_cpumask_bits, that seems to be the
problem, so why not look there?