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Subject: Re: Hard lockups due to "tick/common: Make tick_periodic() check for
 missing ticks"
To:     Qian Cai <cai@lca.pw>, Thomas Gleixner <tglx@linutronix.de>,
        Stephen Rothwell <sfr@canb.auug.org.au>
Cc:     "Joel Fernandes (Google)" <joel@joelfernandes.org>,
        "Paul E. McKenney" <paulmck@kernel.org>, rcu@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Will Deacon <will@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>
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 <11BEA1A5-2E93-4E01-A05C-A6BA73A74CEB@lca.pw>
From:   Waiman Long <longman@redhat.com>
Organization: Red Hat
Message-ID: <218eed57-27c8-12c0-6f5f-111874798c21@redhat.com>
Date:   Thu, 19 Mar 2020 15:00:35 -0400
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On 3/19/20 9:58 AM, Qian Cai wrote:
>
>> On Mar 6, 2020, at 10:33 PM, Qian Cai <cai@lca.pw> wrote:
>>
>>
>>
>>> On Mar 5, 2020, at 11:06 PM, Qian Cai <cai@lca.pw> wrote:
>>>
>> Using this config,
>>
>>> https://raw.githubusercontent.com/cailca/linux-mm/master/x86.config
>> Reverted the linux-next commit d441dceb5dce (=E2=80=9Ctick/common: Mak=
e tick_periodic() check for missing ticks=E2=80=9D)
>> fixed the lockup that could easily happen during boot.
>
> Thomas or Stephen, can you back out this patch from linux-next while Wa=
iman is getting to the bottom of it?
> I can still reproduce it as today.

I am fine for reverting the patch for now. I am still having some
trouble reproducing it and I have other tasks to work on right now. I
will get to the bottom of it and resubmit a new patch later on.

Cheers,
Longman