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Date: Tue, 23 Dec 2025 21:11:36 +0100
Message-Id: <DF5VBOI4LSTZ.5O2XJRIFMK3S@kernel.org>
Subject: Re: [PATCH v5] drm/nova: Align GEM memory allocation to system page
 size
Cc: <acourbot@nvidia.com>, <aliceryhl@google.com>, <joelagnelf@nvidia.com>,
 <airlied@redhat.com>, <rust-for-linux@vger.kernel.org>
To: "Brendan Shephard" <bshephar@bne-home.net>
From: "Danilo Krummrich" <dakr@kernel.org>
References: <20251223135902.35767-1-bshephar@bne-home.net>
In-Reply-To: <20251223135902.35767-1-bshephar@bne-home.net>

On Tue Dec 23, 2025 at 2:59 PM CET, Brendan Shephard wrote:
> diff --git a/drivers/gpu/drm/nova/gem.rs b/drivers/gpu/drm/nova/gem.rs
> index a07e922e25ef..e1b57609b8f7 100644
> --- a/drivers/gpu/drm/nova/gem.rs
> +++ b/drivers/gpu/drm/nova/gem.rs
> @@ -3,10 +3,7 @@
>  use kernel::{
>      drm,
>      drm::{gem, gem::BaseObject},
> -    page::{
> -        page_align,
> -        PAGE_SIZE, //
> -    },
> +    page::page_align,
>      prelude::*,
>      sync::aref::ARef,
>  };
> @@ -31,14 +28,12 @@ fn new(_dev: &NovaDevice, _size: usize) -> impl PinIn=
it<Self, Error> {
>  impl NovaObject {
>      /// Create a new DRM GEM object.
>      pub(crate) fn new(dev: &NovaDevice, size: usize) -> Result<ARef<gem:=
:Object<Self>>> {
> -        // Check for 0 size or potential usize overflow before calling p=
age_align
> -        if size =3D=3D 0 || size > usize::MAX - PAGE_SIZE + 1 {
> +        if size =3D=3D 0 {
>              return Err(EINVAL);
>          }
> -
> -        let aligned_size =3D page_align(size);
> -
> -        gem::Object::new(dev, aligned_size)
> +        page_align(size)
> +            .ok_or(EINVAL)
> +            .and_then(|size| gem::Object::new(dev, size))
>      }
> =20
>      /// Look up a GEM object handle for a `File` and return an `ObjectRe=
f` for it.
>
> base-commit: b927546677c876e26eba308550207c2ddf812a43
> prerequisite-patch-id: 7154ef17c3e40275152c90eff07bffcb5ef5e5cb

This looks like this is an incremental patch on top of some previous versio=
n of
this one.

However, in this case I don't think there is a need to resend, since I pref=
er v4
over this one. Eventually we will need to use size (or aligned_size) outsid=
e of
the closure for further calculations.

I will pick up v4 of this patch, no need to resend, thanks!