FAILED: patch "[PATCH] drm/cma-helper: Set VM_DONTEXPAND for mmap" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-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 <[email protected]>.

thanks,

greg k-h

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

From 59f39bfa6553d598cb22f694d45e89547f420d85 Mon Sep 17 00:00:00 2001
From: Robin Murphy <[email protected]>
Date: Wed, 13 Oct 2021 10:36:54 -0400
Subject: [PATCH] drm/cma-helper: Set VM_DONTEXPAND for mmap

drm_gem_cma_mmap() cannot assume every implementation of dma_mmap_wc() will end up calling remap_pfn_range() (which happens to set the relevant vma flag, among others), so in order to make sure expectations around VM_DONTEXPAND are met, let it explicitly set the flag like most other GEM mmap implementations do.

This avoids repeated warnings on a small minority of systems where the display is behind an IOMMU, and has a simple driver which does not override drm_gem_cma_default_funcs. Arm hdlcd is an in-tree affected driver. Out-of-tree, the Apple DCP driver is affected; this fix is required for DCP to be mainlined.

[Alyssa: Update commit message.]

index cefd0cbf9deb..dc275c466c9c 100644
@@ -512,6 +512,7 @@ int drm_gem_cma_mmap(struct drm_gem_cma_object *cma_obj, struct vm_area_struct *
 	 */
 	vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
 	vma->vm_flags &= ~VM_PFNMAP;
+	vma->vm_flags |= VM_DONTEXPAND;
 
 	if (cma_obj->map_noncoherent) {
 		vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);