Extern or forward variable declaration at include/linux/mmu_notifier.h, line 12 References: arch/powerpc/platforms/powernv/npu-dma.c, line 702 drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c, line 242 drivers/gpu/drm/amd/amdkfd/kfd_process.c, line 438 drivers/gpu/drm/i915/i915_gem_userptr.c, line 159 drivers/gpu/drm/radeon/radeon_mn.c, line 172 drivers/infiniband/core/umem_odp.c, line 253 drivers/infiniband/hw/hfi1/mmu_rb.c, line 79 drivers/iommu/amd_iommu_v2.c, line 429 drivers/iommu/intel-svm.c, line 293 drivers/misc/mic/scif/scif_dma.c, line 225 drivers/misc/sgi-gru/grutlbpurge.c, line 260 drivers/misc/sgi-gru/grutlbpurge.c, line 269 drivers/xen/gntdev.c, line 514 include/linux/mmu_notifier.h, line 12 include/linux/mmu_notifier.h, line 32 include/linux/mmu_notifier.h, line 204 mm/hmm.c, line 48 mm/hmm.c, line 213 virt/kvm/kvm_main.c, line 472