linux-kernel - Re: [PATCH v2 0/3] vhost_task: Fix a bug where KVM wakes an exited task

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Message-ID: <aMw4wx5ENt-odhYS@google.com>
Date: Thu, 18 Sep 2025 09:52:19 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Paolo Bonzini <pbonzini@...hat.com>, 
	Jason Wang <jasowang@...hat.com>, kvm@...r.kernel.org, virtualization@...ts.linux.dev, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/3] vhost_task: Fix a bug where KVM wakes an exited task

On Thu, Sep 18, 2025, Michael S. Tsirkin wrote:
> On Thu, Sep 18, 2025 at 09:04:07AM -0700, Sean Christopherson wrote:
> > On Thu, Sep 18, 2025, Sebastian Andrzej Siewior wrote:
> > > On 2025-09-18 11:09:05 [-0400], Michael S. Tsirkin wrote:
> > > > So how about switching to this approach then?
> > > > Instead of piling up fixes like we seem to do now ...
> > 
> > I don't have a strong preference for 6.17, beyond landing a fix of some kind.
> > I think there are three options for 6.17, in order of "least like to break
> > something":
> > 
> >  1. Sebastian's get_task_struct() fix
> 
> 
> I am just a bit apprehensive that we don't create a situation
> where we leak the task struct somehow, given the limited
> testing time. Can you help me get convinced that risk is 0?

I doubt it, I share same similar concerns about lack of testing.  So I guess
thinking about this again, #2 is probably safer since it'd only impact KVM?

> >  2. This series, without the KILLED sanity check in __vhost_task_wake()
> >  3. This series, with my fixup (with which syzbot was happy)