Correct an error in pmap_promote_pde() that may result in an errant

promotion within the kernel's address space.  Specifically,
pmap_promote_pde() is only called when the page table page (PTP) that
is referenced by the given PDE has a full "use count", i.e., its
wire_count is 512.  Although this guarantees for a user address space
that all 512 PTEs in the PTP hold valid mappings, the same is not true
of the kernel's address space.  A kernel PTP always has a use count of
512 regardless of the state of the PTEs.  Therefore,
pmap_promote_pde() should not assume (or assert) that the first PTE in
the PTP is valid.

0 files changed, 0 insertions, 0 deletions