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Message-ID: <20251128152524.4a2e4fe0@fedora>
Date: Fri, 28 Nov 2025 15:25:24 +0100
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: Danilo Krummrich <dakr@...nel.org>, Daniel Almeida
<daniel.almeida@...labora.com>, Matthew Brost <matthew.brost@...el.com>,
"Thomas Hellström" <thomas.hellstrom@...ux.intel.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
<mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
<airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Steven Price
<steven.price@....com>, Liviu Dudau <liviu.dudau@....com>, Miguel Ojeda
<ojeda@...nel.org>, Boqun Feng <boqun.feng@...il.com>, Gary Guo
<gary@...yguo.net>, "Björn Roy Baron"
<bjorn3_gh@...tonmail.com>, Benno Lossin <lossin@...nel.org>, Andreas
Hindborg <a.hindborg@...nel.org>, Trevor Gross <tmgross@...ch.edu>, Frank
Binns <frank.binns@...tec.com>, Matt Coster <matt.coster@...tec.com>, Rob
Clark <robin.clark@....qualcomm.com>, Dmitry Baryshkov <lumag@...nel.org>,
Abhinav Kumar <abhinav.kumar@...ux.dev>, Jessica Zhang
<jessica.zhang@....qualcomm.com>, Sean Paul <sean@...rly.run>, Marijn
Suijten <marijn.suijten@...ainline.org>, Lyude Paul <lyude@...hat.com>,
Lucas De Marchi <lucas.demarchi@...el.com>, Rodrigo Vivi
<rodrigo.vivi@...el.com>, Sumit Semwal <sumit.semwal@...aro.org>,
"Christian König" <christian.koenig@....com>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
rust-for-linux@...r.kernel.org, linux-arm-msm@...r.kernel.org,
freedreno@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
intel-xe@...ts.freedesktop.org, linux-media@...r.kernel.org,
linaro-mm-sig@...ts.linaro.org
Subject: Re: [PATCH 2/4] drm/gpuvm: drm_gpuvm_bo_obtain() requires lock and
staged mode
On Fri, 28 Nov 2025 14:14:16 +0000
Alice Ryhl <aliceryhl@...gle.com> wrote:
> In the previous commit we updated drm_gpuvm_bo_obtain_prealloc() to take
> locks internally, which means that it's only usable in immediate mode.
> In this commit, we notice that drm_gpuvm_bo_obtain() requires you to use
> staged mode. This means that we now have one variant of obtain for each
> mode you might use gpuvm in.
>
> To reflect this information, we add a warning about using it in
> immediate mode, and to make the distinction clearer we rename the method
> with a _locked() suffix so that it's clear that it requires the caller
> to take the locks.
>
> Signed-off-by: Alice Ryhl <aliceryhl@...gle.com>
> ---
> drivers/gpu/drm/drm_gpuvm.c | 16 +++++++++++++---
The gpuvm changes are
Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
> drivers/gpu/drm/imagination/pvr_vm.c | 2 +-
> drivers/gpu/drm/msm/msm_gem.h | 2 +-
> drivers/gpu/drm/msm/msm_gem_vma.c | 2 +-
> drivers/gpu/drm/nouveau/nouveau_uvmm.c | 2 +-
> drivers/gpu/drm/xe/xe_vm.c | 4 ++--
> include/drm/drm_gpuvm.h | 4 ++--
> 7 files changed, 21 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c
> index f08a5cc1d611f971862c1272987e5ecd6d97c163..9cd06c7600dc32ceee0f0beb5e3daf31698a66b3 100644
> --- a/drivers/gpu/drm/drm_gpuvm.c
> +++ b/drivers/gpu/drm/drm_gpuvm.c
> @@ -1832,16 +1832,26 @@ EXPORT_SYMBOL_GPL(drm_gpuvm_bo_find);
> * count of the &drm_gpuvm_bo accordingly. If not found, allocates a new
> * &drm_gpuvm_bo.
> *
> + * Requires the lock for the GEMs gpuva list.
> + *
> * A new &drm_gpuvm_bo is added to the GEMs gpuva list.
> *
> * Returns: a pointer to the &drm_gpuvm_bo on success, an ERR_PTR on failure
> */
> struct drm_gpuvm_bo *
> -drm_gpuvm_bo_obtain(struct drm_gpuvm *gpuvm,
> - struct drm_gem_object *obj)
> +drm_gpuvm_bo_obtain_locked(struct drm_gpuvm *gpuvm,
> + struct drm_gem_object *obj)
> {
> struct drm_gpuvm_bo *vm_bo;
>
> + /*
> + * In immediate mode this would require the caller to hold the GEMs
> + * gpuva mutex, but it's not okay to allocate while holding that lock,
> + * and this method allocates. Immediate mode drivers should use
> + * drm_gpuvm_bo_obtain_prealloc() instead.
> + */
> + drm_WARN_ON(gpuvm->drm, drm_gpuvm_immediate_mode(gpuvm));
> +
> vm_bo = drm_gpuvm_bo_find(gpuvm, obj);
> if (vm_bo)
> return vm_bo;
> @@ -1855,7 +1865,7 @@ drm_gpuvm_bo_obtain(struct drm_gpuvm *gpuvm,
>
> return vm_bo;
> }
> -EXPORT_SYMBOL_GPL(drm_gpuvm_bo_obtain);
> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_obtain_locked);
>
> /**
> * drm_gpuvm_bo_obtain_prealloc() - obtains an instance of the &drm_gpuvm_bo
> diff --git a/drivers/gpu/drm/imagination/pvr_vm.c b/drivers/gpu/drm/imagination/pvr_vm.c
> index 3d97990170bf6b1341116c5c8b9d01421944eda4..30ff9b84eb14f2455003e76108de6d489a13f61a 100644
> --- a/drivers/gpu/drm/imagination/pvr_vm.c
> +++ b/drivers/gpu/drm/imagination/pvr_vm.c
> @@ -255,7 +255,7 @@ pvr_vm_bind_op_map_init(struct pvr_vm_bind_op *bind_op,
> bind_op->type = PVR_VM_BIND_TYPE_MAP;
>
> dma_resv_lock(obj->resv, NULL);
> - bind_op->gpuvm_bo = drm_gpuvm_bo_obtain(&vm_ctx->gpuvm_mgr, obj);
> + bind_op->gpuvm_bo = drm_gpuvm_bo_obtain_locked(&vm_ctx->gpuvm_mgr, obj);
> dma_resv_unlock(obj->resv);
> if (IS_ERR(bind_op->gpuvm_bo))
> return PTR_ERR(bind_op->gpuvm_bo);
> diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
> index a4cf31853c5008e171c3ad72cde1004c60fe5212..26dfe3d22e3e847f7e63174481d03f72878a8ced 100644
> --- a/drivers/gpu/drm/msm/msm_gem.h
> +++ b/drivers/gpu/drm/msm/msm_gem.h
> @@ -60,7 +60,7 @@ struct msm_gem_vm_log_entry {
> * embedded in any larger driver structure. The GEM object holds a list of
> * drm_gpuvm_bo, which in turn holds a list of msm_gem_vma. A linked vma
> * holds a reference to the vm_bo, and drops it when the vma is unlinked.
> - * So we just need to call drm_gpuvm_bo_obtain() to return a ref to an
> + * So we just need to call drm_gpuvm_bo_obtain_locked() to return a ref to an
> * existing vm_bo, or create a new one. Once the vma is linked, the ref
> * to the vm_bo can be dropped (since the vma is holding one).
> */
> diff --git a/drivers/gpu/drm/msm/msm_gem_vma.c b/drivers/gpu/drm/msm/msm_gem_vma.c
> index 8316af1723c227f919594446c3721e1a948cbc9e..239b6168a26e636b511187b4993945d1565d149f 100644
> --- a/drivers/gpu/drm/msm/msm_gem_vma.c
> +++ b/drivers/gpu/drm/msm/msm_gem_vma.c
> @@ -413,7 +413,7 @@ msm_gem_vma_new(struct drm_gpuvm *gpuvm, struct drm_gem_object *obj,
> if (!obj)
> return &vma->base;
>
> - vm_bo = drm_gpuvm_bo_obtain(&vm->base, obj);
> + vm_bo = drm_gpuvm_bo_obtain_locked(&vm->base, obj);
> if (IS_ERR(vm_bo)) {
> ret = PTR_ERR(vm_bo);
> goto err_va_remove;
> diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> index 79eefdfd08a2678fedf69503ddf7e9e17ed14c6f..d8888bd29cccef4b8dad9eff2bf6e2b1fd1a7e4d 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> @@ -1207,7 +1207,7 @@ nouveau_uvmm_bind_job_submit(struct nouveau_job *job,
> return -ENOENT;
>
> dma_resv_lock(obj->resv, NULL);
> - op->vm_bo = drm_gpuvm_bo_obtain(&uvmm->base, obj);
> + op->vm_bo = drm_gpuvm_bo_obtain_locked(&uvmm->base, obj);
> dma_resv_unlock(obj->resv);
> if (IS_ERR(op->vm_bo))
> return PTR_ERR(op->vm_bo);
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index f602b874e0547591d9008333c18f3de0634c48c7..de52d01b0921cc8ac619deeed47b578e0ae69257 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -1004,7 +1004,7 @@ static struct xe_vma *xe_vma_create(struct xe_vm *vm,
>
> xe_bo_assert_held(bo);
>
> - vm_bo = drm_gpuvm_bo_obtain(vma->gpuva.vm, &bo->ttm.base);
> + vm_bo = drm_gpuvm_bo_obtain_locked(vma->gpuva.vm, &bo->ttm.base);
> if (IS_ERR(vm_bo)) {
> xe_vma_free(vma);
> return ERR_CAST(vm_bo);
> @@ -2249,7 +2249,7 @@ vm_bind_ioctl_ops_create(struct xe_vm *vm, struct xe_vma_ops *vops,
> if (err)
> return ERR_PTR(err);
>
> - vm_bo = drm_gpuvm_bo_obtain(&vm->gpuvm, obj);
> + vm_bo = drm_gpuvm_bo_obtain_locked(&vm->gpuvm, obj);
> if (IS_ERR(vm_bo)) {
> xe_bo_unlock(bo);
> return ERR_CAST(vm_bo);
> diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
> index fdfc575b260360611ff8ce16c327acede787929f..0d3fc1f6cac9966a42f3bc82b0b491bfefaf5b96 100644
> --- a/include/drm/drm_gpuvm.h
> +++ b/include/drm/drm_gpuvm.h
> @@ -736,8 +736,8 @@ drm_gpuvm_bo_create(struct drm_gpuvm *gpuvm,
> struct drm_gem_object *obj);
>
> struct drm_gpuvm_bo *
> -drm_gpuvm_bo_obtain(struct drm_gpuvm *gpuvm,
> - struct drm_gem_object *obj);
> +drm_gpuvm_bo_obtain_locked(struct drm_gpuvm *gpuvm,
> + struct drm_gem_object *obj);
> struct drm_gpuvm_bo *
> drm_gpuvm_bo_obtain_prealloc(struct drm_gpuvm_bo *vm_bo);
>
>
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