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Subject: Re: [PATCH] KVM: X86: Fix softlockup when get the current kvmclock
 timestamp
To: Wanpeng Li <kernellwp@gmail.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Wanpeng Li <wanpeng.li@hotmail.com>
References: <1509929721-3027-1-git-send-email-wanpeng.li@hotmail.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <5b0d3e0b-141f-b18b-d74a-bc56265d34df@redhat.com>
Date: Mon, 6 Nov 2017 10:29:40 +0100
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On 06/11/2017 01:55, Wanpeng Li wrote:
> This can be reproduced when running kvm-unit-tests/hyperv_stimer.flat and 
> cpu-hotplug stress simultaneously. kvm_get_time_scale() takes too long which 
> results in softlockup.

Apart from the pr_debug, kvm_get_time_scale should take less than a
microsecond.  The patch is fine, but can you confirm that pr_debug is
the culprit?

Thanks,

Paolo