K 10
svn:author
V 3
alc
K 8
svn:date
V 27
2019-11-27T19:34:33.348465Z
K 7
svn:log
V 789
MFC r350579,r350741,r352584
  Enable superpage promotion within the kernel pmap.

  Ordinarily, during a superpage promotion or demotion within a pmap, the
  pmap's lock ensures that other operations on the pmap don't observe the
  old mapping being broken before the new mapping is established.  However,
  pmap_kextract() doesn't acquire the kernel pmap's lock, so it may observe
  the broken mapping.  And, if it does, it returns an incorrect result.

  This revision implements a lock-free solution to this problem in
  pmap_update_entry() and pmap_kextract() because pmap_kextract() can't
  acquire the kernel pmap's lock.

  In case a translation fault on the kernel address space occurs from
  within a critical section, we must perform a lock-free check on the
  faulting address.

END