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Date:   Fri, 10 Jan 2020 14:42:36 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Qais Yousef <qais.yousef@arm.com>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Iurii Zaikin <yzaikin@google.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        valentin.schneider@arm.com, qperret@google.com,
        Patrick Bellasi <patrick.bellasi@matbug.net>,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] sched/rt: Add a new sysctl to control uclamp_util_min
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On Thu, Jan 09, 2020 at 01:00:58PM +0000, Qais Yousef wrote:
> On 01/08/20 14:44, Peter Zijlstra wrote:

> > Did cpu_uclamp_write() forget to check for input<0 ?
> 
> Hmm just tried that and it seems so
> 
> # echo -1 > cpu.uclamp.min
> # cat cpu.uclamp.min
> 42949671.96
> 
> capacity_from_percent(); we check for
> 
> 7301                 if (req.percent > UCLAMP_PERCENT_SCALE) {
> 7302                         req.ret = -ERANGE;
> 7303                         return req;
> 7304                 }
> 
> But req.percent is s64, maybe it should be u64?

		if ((u64)req.percent > UCLAMP_PERCENT_SCALE)

should do, I think.