From c17c1b915d3111d18a76bf56ac4f95d6a2cf5c17 Mon Sep 17 00:00:00 2001
From: jchandra <jchandra@FreeBSD.org>
Date: Fri, 6 Aug 2010 07:32:33 +0000
Subject: Fix the issue reported by alc:

 pmap_page_wired_mappings() counts the number of pv entries for the
 specified page that have the pv entry wired flag set to TRUE.
 pmap_enter() correctly initializes this flag.  However,
 pmap_change_wiring() doesn't update the corresponding pv entry flag,
 only the PTE.  So, the count returned by pmap_page_wired_mappings()
 will sometimes be wrong.

 In the short term, the best fix would be to eliminate the pv entry
 flag and use only the PTE.  That flag is wasting non-trivial memory.

Remove pv_wired flag, and use PTE flag to count the wired mappings.

Reviewed by:	alc
---
 sys/mips/include/pmap.h |  1 -
 sys/mips/mips/pmap.c    | 15 ++++++++++-----
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/sys/mips/include/pmap.h b/sys/mips/include/pmap.h
index 3e7b937..0b4ef8a 100644
--- a/sys/mips/include/pmap.h
+++ b/sys/mips/include/pmap.h
@@ -124,7 +124,6 @@ typedef struct pv_entry {
 	TAILQ_ENTRY(pv_entry) pv_list;
 	TAILQ_ENTRY(pv_entry) pv_plist;
 	vm_page_t pv_ptem;	/* VM page for pte */
-	boolean_t pv_wired;	/* whether this entry is wired */
 }       *pv_entry_t;
 
 
diff --git a/sys/mips/mips/pmap.c b/sys/mips/mips/pmap.c
index f6b7e6f..ecba6ff 100644
--- a/sys/mips/mips/pmap.c
+++ b/sys/mips/mips/pmap.c
@@ -1473,7 +1473,6 @@ pmap_try_insert_pv_entry(pmap_t pmap, vm_page_t mpte, vm_offset_t va,
 		pv->pv_va = va;
 		pv->pv_pmap = pmap;
 		pv->pv_ptem = mpte;
-		pv->pv_wired = FALSE;
 		TAILQ_INSERT_TAIL(&pmap->pm_pvlist, pv, pv_plist);
 		TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
 		m->md.pv_list_count++;
@@ -1897,7 +1896,6 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_prot_t access, vm_page_t m,
 		pv->pv_va = va;
 		pv->pv_pmap = pmap;
 		pv->pv_ptem = mpte;
-		pv->pv_wired = wired;
 		TAILQ_INSERT_TAIL(&pmap->pm_pvlist, pv, pv_plist);
 		TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
 		m->md.pv_list_count++;
@@ -2655,15 +2653,22 @@ int
 pmap_page_wired_mappings(vm_page_t m)
 {
 	pv_entry_t pv;
+	pmap_t pmap;
+	pt_entry_t *pte;
 	int count;
 
 	count = 0;
 	if ((m->flags & PG_FICTITIOUS) != 0)
 		return (count);
 	vm_page_lock_queues();
-	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list)
-	    if (pv->pv_wired)
-		count++;
+	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
+		pmap = pv->pv_pmap;
+		PMAP_LOCK(pmap);
+		pte = pmap_pte(pmap, pv->pv_va);
+		if (pte_test(pte, PTE_W))
+			count++;
+		PMAP_UNLOCK(pmap);
+	}
 	vm_page_unlock_queues();
 	return (count);
 }
-- 
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