svn commit: r348630 - head/sys/amd64/amd64

[Alan Cox]

Author: alc
Date: Tue Jun  4 16:21:14 2019
New Revision: 348630
URL: https://svnweb.freebsd.org/changeset/base/348630

Log:
  The changes to pmap_demote_pde_locked()'s control flow in r348476 resulted
  in the loss of a KASSERT that guarded against the invalidation a wired
  mapping.  Restore this KASSERT.
  
  Remove an unnecessary KASSERT from pmap_demote_pde_locked().  It guards
  against a state that was already handled at the start of the function.
  
  Reviewed by:	kib
  X-MFC with:	r348476

Modified:
  head/sys/amd64/amd64/pmap.c

Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c	Tue Jun  4 16:07:01 2019	(r348629)
+++ head/sys/amd64/amd64/pmap.c	Tue Jun  4 16:21:14 2019	(r348630)
@@ -4565,6 +4565,8 @@ pmap_demote_pde_locked(pmap_t pmap, pd_entry_t *pde, v
 	 * mapping was never accessed.
 	 */
 	if ((oldpde & PG_A) == 0) {
+		KASSERT((oldpde & PG_W) == 0,
+		    ("pmap_demote_pde: a wired mapping is missing PG_A"));
 		pmap_demote_pde_abort(pmap, va, pde, oldpde, lockp);
 		return (FALSE);
 	}
@@ -4615,8 +4617,6 @@ pmap_demote_pde_locked(pmap_t pmap, pd_entry_t *pde, v
 	mptepa = VM_PAGE_TO_PHYS(mpte);
 	firstpte = (pt_entry_t *)PHYS_TO_DMAP(mptepa);
 	newpde = mptepa | PG_M | PG_A | (oldpde & PG_U) | PG_RW | PG_V;
-	KASSERT((oldpde & PG_A) != 0,
-	    ("pmap_demote_pde: oldpde is missing PG_A"));
 	KASSERT((oldpde & (PG_M | PG_RW)) != PG_RW,
 	    ("pmap_demote_pde: oldpde is missing PG_M"));
 	newpte = oldpde & ~PG_PS;