On Mon, Aug 26, 2019 at 02:35:25PM -0700, maksim yevmenkin wrote:
> 
> 
> > On Aug 26, 2019, at 9:14 AM, Warner Losh <imp@bsdimp.com> wrote:
> > 
> > Is it from read_connection_list? If so I have a 'patch' that I'm using but
> > haven't committed because it's just too gross: drop the lock before the
> > copyout and pick it up again after...
> > 
> 
> Hmm... interesting.... 
> 
> I only took a brief look at it. I suppose I can ensure user space address is wired and then copyout() can be called with mutex held

No, you cannot do this, at least without making the kernel to panic.
User might unmap the wired mapping at any time still.

> 
> It’s odd that I’ve never seen this before. I’m traveling at the moment will take a closer look this later this week
> 
> Thanks
> Max
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