The patch below does not apply to the 6.16-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.16.y git checkout FETCH_HEAD git cherry-pick -x 8a9b978ebd47df9e0694c34748c2d6fa0c31eb4d # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025082112-ecologist-starry-b438@gregkh' --subject-prefix 'PATCH 6.16.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8a9b978ebd47df9e0694c34748c2d6fa0c31eb4d Mon Sep 17 00:00:00 2001 From: Himal Prasad Ghimiray himal.prasad.ghimiray@intel.com Date: Mon, 12 May 2025 06:54:55 -0700 Subject: [PATCH] drm/gpusvm: Introduce devmem_only flag for allocation

This commit adds a new flag, devmem_only, to the drm_gpusvm structure. The purpose of this flag is to ensure that the get_pages function allocates memory exclusively from the device's memory. If the allocation from device memory fails, the function will return an -EFAULT error.

Required for shared CPU and GPU atomics on certain devices.

v3: - s/vram_only/devmem_only/

Fixes: 99624bdff867 ("drm/gpusvm: Add support for GPU Shared Virtual Memory") Cc: stable@vger.kernel.org Signed-off-by: Matthew Brost matthew.brost@intel.com Signed-off-by: Himal Prasad Ghimiray himal.prasad.ghimiray@intel.com Reviewed-by: Matthew Brost matthew.brost@intel.com Link: https://lore.kernel.org/r/20250512135500.1405019-2-matthew.brost@intel.com

diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c index de424e670995..a58d03e6cac2 100644 --- a/drivers/gpu/drm/drm_gpusvm.c +++ b/drivers/gpu/drm/drm_gpusvm.c @@ -1454,6 +1454,11 @@ int drm_gpusvm_range_get_pages(struct drm_gpusvm *gpusvm, goto err_unmap; }

+ if (ctx->devmem_only) { + err = -EFAULT; + goto err_unmap; + } + addr = dma_map_page(gpusvm->drm->dev, page, 0, PAGE_SIZE << order, diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h index df120b4d1f83..9fd25fc880a4 100644 --- a/include/drm/drm_gpusvm.h +++ b/include/drm/drm_gpusvm.h @@ -286,6 +286,7 @@ struct drm_gpusvm { * @in_notifier: entering from a MMU notifier * @read_only: operating on read-only memory * @devmem_possible: possible to use device memory + * @devmem_only: use only device memory * * Context that is DRM GPUSVM is operating in (i.e. user arguments). */ @@ -294,6 +295,7 @@ struct drm_gpusvm_ctx { unsigned int in_notifier :1; unsigned int read_only :1; unsigned int devmem_possible :1; + unsigned int devmem_only :1; };

int drm_gpusvm_init(struct drm_gpusvm *gpusvm,