From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jan Kara <jack@suse.cz>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
linux-ext4@vger.kernel.org, "Theodore Ts'o" <tytso@mit.edu>,
linux-kernel@vger.kernel.org,
Josh Triplett <josh@joshtriplett.org>,
kvm@vger.kernel.org
Subject: Re: kernel/rcu/tree.c:1031 rcu_irq_enter() invoked with irqs enabled!!!!
Date: Wed, 26 Apr 2017 16:39:20 +0200 [thread overview]
Message-ID: <20170426143920.GA27155@potion> (raw)
In-Reply-To: <43412479-18a3-0c55-3d32-97c15ee5fe87@redhat.com>
2017-04-26 16:29+0200, Paolo Bonzini:
> On 26/04/2017 16:18, Radim Krčmář wrote:
>>> OK, but looking at the stack trace, this has nothing to do with ext4. The
>>> problem seems to be in KVM - relevant CCs added.
>> The path begins with async_page_fault interrupt gate and the hardware
>> should clear the interrupt flag before executing it. I don't see a
>> change that would break the assumption that interrupts are disabled ...
>
> native_safe_halt enables interrupts. I think this is it:
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 14f65a5f938e..2a7835932b71 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -161,8 +161,8 @@ void kvm_async_pf_task_wait(u32 token)
> */
> rcu_irq_exit();
> native_safe_halt();
> - rcu_irq_enter();
> local_irq_disable();
> + rcu_irq_enter();
> }
> }
> if (!n.halted)
We called rcu_irq_enter() there twice, *facepalm*.
Yes, that patch should fix it.
prev parent reply other threads:[~2017-04-26 14:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 20:13 kernel/rcu/tree.c:1031 rcu_irq_enter() invoked with irqs enabled!!!! Ross Zwisler
2017-04-25 20:28 ` Paul E. McKenney
2017-04-26 7:16 ` Jan Kara
2017-04-26 14:18 ` Radim Krčmář
2017-04-26 14:29 ` Paolo Bonzini
2017-04-26 14:39 ` Radim Krčmář [this message]
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