linux-kernel - Re: [PATCH 1/1] vhost: Protect the virtqueue from being cleared whilst still in use

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Message-ID: <20220308060210-mutt-send-email-mst@kernel.org>
Date:   Tue, 8 Mar 2022 06:05:24 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Lee Jones <lee.jones@...aro.org>, jasowang@...hat.com,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        stable@...r.kernel.org,
        syzbot+adc3cb32385586bec859@...kaller.appspotmail.com
Subject: Re: [PATCH 1/1] vhost: Protect the virtqueue from being cleared
 whilst still in use

On Tue, Mar 08, 2022 at 09:57:57AM +0100, Greg KH wrote:
> > > And what happens if the mutex is locked _RIGHT_ after you checked it?
> > > You still have a race...
> > 
> > No, we miss a warning that one time.  Memory is still protected.
> 
> Then don't warn on something that doesn't matter.  This line can be
> dropped as there's nothing anyone can do about it, right?

I mean, the reason I wanted the warning is because there's a kernel
bug, and it will break userspace. warning is just telling us this.
is the bug reacheable from userspace? if we knew that we won't
need the lock ...

-- 
MST