[PATCH AUTOSEL 5.18 38/53] drm/xen: Add missing VM_DONTEXPAND flag in mmap callback

[Sasha Levin <sashal@xxxxxxxxxx>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

[ Upstream commit ca6969013d13282b42cb5edcc13db731a08e0ad8 ]

With Xen PV Display driver in use the "expected" VM_DONTEXPAND flag
is not set (neither explicitly nor implicitly), so the driver hits
the code path in drm_gem_mmap_obj() which triggers the WARNING.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
Link: 
https://lore.kernel.org/r/1652104303-5098-1-git-send-email-olekstysh@xxxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/xen/xen_drm_front_gem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c 
b/drivers/gpu/drm/xen/xen_drm_front_gem.c
index 5a5bf4e5b717..e31554d7139f 100644
--- a/drivers/gpu/drm/xen/xen_drm_front_gem.c
+++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
@@ -71,7 +71,7 @@ static int xen_drm_front_gem_object_mmap(struct 
drm_gem_object *gem_obj,
         * the whole buffer.
         */
        vma->vm_flags &= ~VM_PFNMAP;
-       vma->vm_flags |= VM_MIXEDMAP;
+       vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
        vma->vm_pgoff = 0;
 
        /*
-- 
2.35.1