I've bisected this to:

commit 9021d2edd259d992cf8b5b48791ab50829129de7                                 
Author: Christian König <christian.koenig@amd.com>                              
Date:   Mon Feb 19 11:29:35 2018 +0100                                          

    drm/amdgpu: mitigate workaround for i915                                    

    To be able to use DRI_PRIME with amdgpu and i915 we add all our fences      
    only as exclusive ones.                                                     

    Disable that behavior when sharing between amdgpu itself cause it           
    hinders concurrent execution.                                               

    Signed-off-by: Christian König <christian.koenig@amd.com>                   
    Reviewed-by: Alex Deucher <alexander.deucher@amd.com>                       
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>   

If I revert that and a bit of:

commit 59dd47728625e6f8e77f888d00596c9fb7057540
Author: Christian König <christian.koenig@amd.com>
Date:   Tue Feb 20 19:51:02 2018 +0100

    drm/amdgpu: further mitigate workaround for i915

    Disable the workaround on imported BOs as well.

    Signed-off-by: Christian König <christian.koenig@amd.com>
    Reviewed-by: Alex Deucher <alexdeucher@amd.com>                             
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>   

To work around the compilation issue, things go back to normal