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From:   Wanpeng Li <kernellwp@gmail.com>
Date:   Wed, 29 Jul 2020 10:38:18 +0800
Message-ID: <CANRm+CwrT=gxxgkNdT3wFwzWYYh3FFrUU=aTqH8VT=MraU7jkw@mail.gmail.com>
Subject: Re: WARNING: suspicious RCU usage - while installing a VM on a CPU
 listed under nohz_full
To:     Nitesh Narayan Lal <nitesh@redhat.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        KVM list <kvm@vger.kernel.org>,
        Wanpeng Li <wanpengli@tencent.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Liran Alon <liran.alon@oracle.com>,
        "frederic@kernel.org" <frederic@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Juri Lelli <juri.lelli@redhat.com>
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Hi Nitesh=EF=BC=8C
On Wed, 29 Jul 2020 at 09:00, Wanpeng Li <kernellwp@gmail.com> wrote:
>
> On Tue, 28 Jul 2020 at 22:40, Nitesh Narayan Lal <nitesh@redhat.com> wrot=
e:
> >
> > Hi,
> >
> > I have recently come across an RCU trace with the 5.8-rc7 kernel that h=
as the
> > debug configs enabled while installing a VM on a CPU that is listed und=
er
> > nohz_full.
> >
> > Based on some of the initial debugging, my impression is that the issue=
 is
> > triggered because of the fastpath that is meant to optimize the writes =
to x2APIC
> > ICR that eventually leads to a virtual IPI in fixed delivery mode, is g=
etting
> > invoked from the quiescent state.

Could you try latest linux-next tree? I guess maybe some patches are
pending in linux-next tree, I can't reproduce against linux-next tree.