linux-kernel - Re: [PATCH] KVM: guest_memfd: Define a CLASS to get+put guest

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Message-ID: <176097601867.439156.11041449627994730588.b4-ty@google.com>
Date: Mon, 20 Oct 2025 09:33:03 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: guest_memfd: Define a CLASS to get+put guest_memfd
 file from a memslot

On Tue, 07 Oct 2025 15:23:56 -0700, Sean Christopherson wrote:
> Add a CLASS to handle getting and putting a guest_memfd file given a
> memslot to reduce the amount of related boilerplate, and more importantly
> to minimize the chances of forgetting to put the file (thankfully the bug
> that prompted this didn't escape initial testing).
> 
> Define a CLASS instead of using __free(fput) as _free() comes with subtle
> caveats related to FILO ordering (objects are freed in the order in which
> they are declared), and the recommended solution/workaround (declare file
> pointers exactly when they are initialized) is visually jarring relative
> to KVM's (and the kernel's) overall strict adherence to not mixing
> declarations and code.  E.g. the use in kvm_gmem_populate() would be:
> 
> [...]

Applied to kvm-x86 gmem, thanks!

[1/1] KVM: guest_memfd: Define a CLASS to get+put guest_memfd file from a memslot
      https://github.com/kvm-x86/linux/commit/0bb4d9c39b76

--
https://github.com/kvm-x86/linux/tree/next