Comment 1 for bug 1864775

Skipped:
 * Revert "ovl: modify ovl_permission() to do checks on two inodes"

resolved some minor conflicts with:
 * of: Add OF_DMA_DEFAULT_COHERENT & select it on powerpc
 * KVM: x86: Protect kvm_hv_msr_[get|set]_crash_data() from Spectre-v1/L1TF attacks
 * libertas: don't exit from lbs_ibss_join_existing() with RCU read lock held
 * dm: fix potential for q->make_request_fn NULL pointer