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Date:   Fri, 14 Apr 2023 17:06:06 -0700
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Subject: Re: [PATCH v7 00/14] KVM: mm: fd-based approach for supporting KVM
 guest private memory
From:   Sean Christopherson <seanjc@google.com>
To:     Ackerley Tng <ackerleytng@google.com>
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On Fri, Apr 14, 2023, Sean Christopherson wrote:
> On Fri, Apr 14, 2023, Ackerley Tng wrote:
> > Sean Christopherson <seanjc@google.com> writes:
> > > 	if (WARN_ON_ONCE(file->private_data)) {
> > > 		err = -EEXIST;
> > > 		goto err_fd;
> > > 	}
> > 
> > Did you intend this as a check that the backing filesystem isn't using
> > the private_data field in the mapping?
> >
> > I think you meant file->f_mapping->private_data.
> 
> Ya, sounds right.  I should have added disclaimers that (a) I wrote this quite
> quickly and (b) it's compile tested only at this point.

FWIW, here's a very lightly tested version that doesn't explode on a basic selftest.

https://github.com/sean-jc/linux/tree/x86/upm_base_support