linux-kernel - Re: [RFC PATCH v1 26/37] KVM: selftests: guest_memfd: Test that shared/private status is consistent across processes

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Message-ID: <diqzcy6lp0h9.fsf@google.com>
Date: Fri, 17 Oct 2025 16:33:38 -0700
From: Ackerley Tng <ackerleytng@...gle.com>
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Subject: Re: [RFC PATCH v1 26/37] KVM: selftests: guest_memfd: Test that
 shared/private status is consistent across processes

Ackerley Tng <ackerleytng@...gle.com> writes:

> From: Sean Christopherson <seanjc@...gle.com>
>
> Add a test to verify that a guest_memfd's shared/private status is
> consistent across processes.
>

Missed copying Sean's note from [1]. Rephrased:

Test that on shared to private conversion, any shared pages previously
mapped in any process are unmapped from all processes.

[1] https://lore.kernel.org/all/aN7U1ewx8dNOKl1n@google.com/

> The test forks a child process after creating the shared guest_memfd
> region so that the second process exists alongside the main process for the
> entire test.
>
> The processes then take turns to access memory to check that the
> shared/private status is consistent across processes.
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> Co-developed-by: Ackerley Tng <ackerleytng@...gle.com>
> Signed-off-by: Ackerley Tng <ackerleytng@...gle.com>
> ---
>  .../kvm/guest_memfd_conversions_test.c        | 74 +++++++++++++++++++
>  1 file changed, 74 insertions(+)
>
> 
> [...snip...]
>