[PATCH 2/15] ptwalk: change_protection

Begin the pagetable walker cleanup with a straightforward example, mprotect's change_protection. Started out from Nick Piggin's for_each proposal, but I prefer less hidden; and these are all do while loops, which degrade slightly when converted to for loops. Firmly agree with Andi and Nick that

[PATCH 2/15] ptwalk: change_protection

Begin the pagetable walker cleanup with a straightforward example, mprotect's change_protection. Started out from Nick Piggin's for_each proposal, but I prefer less hidden; and these are all do while loops, which degrade slightly when converted to for loops. Firmly agree with Andi and Nick that