FAILED: patch "[PATCH] drm/gpusvm: Introduce devmem_only flag for allocation" failed to apply to 6.16-stable tree

[<gregkh@linuxfoundation.org>]

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,