While looking at "x86_64/mm: map and unmap page tables in destroy_compat_m2p_mapping" it occurred to me that the mappings changed there can be dropped altogether, as can the linear address range used for this. Note that both patches have only been lightly tested so far, I guess in particular the 2nd one may still have issues.
1: x86: drop unnecessary page table walking in compat r/o M2P handling 2: x86: drop high compat r/o M2P table address range Jan
