Date: Mon, 7 Dec 2015 20:01:23 +0100
From: Frederic Weisbecker <fweisbec@gmail.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: tglx@linutronix.de, peterz@infradead.org, preeti@linux.vnet.ibm.com,
        viresh.kumar@linaro.org, mtosatti@redhat.com,
        linux-kernel@vger.kernel.org, sasha.levin@oracle.com
Subject: Re: Possible issue with commit 4961b6e11825?
Message-ID: <20151207190120.GB20032@lerouge>
References: <20151204232022.GA15891@linux.vnet.ibm.com>
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On Fri, Dec 04, 2015 at 03:20:22PM -0800, Paul E. McKenney wrote:
> Hello!
> 
> Are there any known issues with commit 4961b6e11825 (sched: core: Use
> hrtimer_start[_expires]())?
> 
> The reason that I ask is that I am about 90% sure that an rcutorture
> failure bisects to that commit.  I will be running more tests on
> 3497d206c4d9 (perf: core: Use hrtimer_start()), which is the predecessor
> of 4961b6e11825, and which, unlike 4961b6e11825, passes a 12-hour
> rcutorture test with scenario TREE03.  In contrast, 4961b6e11825 gets
> 131 RCU CPU stall warnings, 132 reports of one of RCU's grace-period
> kthreads being starved, and 525 reports of one of rcutorture's kthreads
> being starved.  Most of the test runs hang on shutdown, which is no
> surprise if an RCU CPU stall is happening at about that time.

I have no idea what the issue is but maybe you have the RCU stall backtrace
somewhere?
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