Roughly half of a typical pmap_mincore() implementation is machine-

independent code.  Move this code into mincore(), and eliminate the
page queues lock from pmap_mincore().

Push down the page queues lock into pmap_clear_modify(),
pmap_clear_reference(), and pmap_is_modified().  Assert that these
functions are never passed an unmanaged page.

Eliminate an inaccurate comment from powerpc/powerpc/mmu_if.m:
Contrary to what the comment says, pmap_mincore() is not simply an
optimization.  Without a complete pmap_mincore() implementation,
mincore() cannot return either MINCORE_MODIFIED or MINCORE_REFERENCED
because only the pmap can provide this information.

Eliminate the page queues lock from vfs_setdirty_locked_object(),
vm_pageout_clean(), vm_object_page_collect_flush(), and
vm_object_page_clean().  Generally speaking, these are all accesses
to the page's dirty field, which are synchronized by the containing
vm object's lock.

Reduce the scope of the page queues lock in vm_object_madvise() and
vm_page_dontneed().

Reviewed by:	kib (an earlier version)

1 files changed, 55 insertions, 56 deletions

diff --git a/sys/ia64/ia64/pmap.c b/sys/ia64/ia64/pmap.c
index d2c5613..86f3ea1 100644
--- a/sys/ia64/ia64/pmap.c
+++ b/sys/ia64/ia64/pmap.c
@@ -1981,10 +1981,20 @@ pmap_is_modified(vm_page_t m)
 	pv_entry_t pv;
 	boolean_t rv;
 
+	KASSERT((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0,
+	    ("pmap_is_modified: page %p is not managed", m));
 	rv = FALSE;
-	if (m->flags & PG_FICTITIOUS)
-		return (rv);
 
+	/*
+	 * If the page is not VPO_BUSY, then PG_WRITEABLE cannot be
+	 * concurrently set while the object is locked.  Thus, if PG_WRITEABLE
+	 * is clear, no PTEs can be dirty.
+	 */
+	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	if ((m->oflags & VPO_BUSY) == 0 &&
+	    (m->flags & PG_WRITEABLE) == 0)
+		return (rv);
+	vm_page_lock_queues();
 	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
 		PMAP_LOCK(pv->pv_pmap);
 		oldpmap = pmap_switch(pv->pv_pmap);
@@ -1996,7 +2006,7 @@ pmap_is_modified(vm_page_t m)
 		if (rv)
 			break;
 	}
-
+	vm_page_unlock_queues();
 	return (rv);
 }
 
@@ -2058,9 +2068,20 @@ pmap_clear_modify(vm_page_t m)
 	pmap_t oldpmap;
 	pv_entry_t pv;
 
-	if (m->flags & PG_FICTITIOUS)
-		return;
+	KASSERT((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0,
+	    ("pmap_clear_modify: page %p is not managed", m));
+	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
+	KASSERT((m->oflags & VPO_BUSY) == 0,
+	    ("pmap_clear_modify: page %p is busy", m));
 
+	/*
+	 * If the page is not PG_WRITEABLE, then no PTEs can be modified.
+	 * If the object containing the page is locked and the page is not
+	 * VPO_BUSY, then PG_WRITEABLE cannot be concurrently set.
+	 */
+	if ((m->flags & PG_WRITEABLE) == 0)
+		return;
+	vm_page_lock_queues();
 	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
 		PMAP_LOCK(pv->pv_pmap);
 		oldpmap = pmap_switch(pv->pv_pmap);
@@ -2073,6 +2094,7 @@ pmap_clear_modify(vm_page_t m)
 		pmap_switch(oldpmap);
 		PMAP_UNLOCK(pv->pv_pmap);
 	}
+	vm_page_unlock_queues();
 }
 
 /*
@@ -2087,9 +2109,9 @@ pmap_clear_reference(vm_page_t m)
 	pmap_t oldpmap;
 	pv_entry_t pv;
 
-	if (m->flags & PG_FICTITIOUS)
-		return;
-
+	KASSERT((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0,
+	    ("pmap_clear_reference: page %p is not managed", m));
+	vm_page_lock_queues();
 	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
 		PMAP_LOCK(pv->pv_pmap);
 		oldpmap = pmap_switch(pv->pv_pmap);
@@ -2102,6 +2124,7 @@ pmap_clear_reference(vm_page_t m)
 		pmap_switch(oldpmap);
 		PMAP_UNLOCK(pv->pv_pmap);
 	}
+	vm_page_unlock_queues();
 }
 
 /*
@@ -2178,13 +2201,15 @@ pmap_unmapdev(vm_offset_t va, vm_size_t size)
  * perform the pmap work for mincore
  */
 int
-pmap_mincore(pmap_t pmap, vm_offset_t addr)
+pmap_mincore(pmap_t pmap, vm_offset_t addr, vm_paddr_t *locked_pa)
 {
 	pmap_t oldpmap;
 	struct ia64_lpte *pte, tpte;
-	int val = 0;
+	vm_paddr_t pa;
+	int val;
 	
 	PMAP_LOCK(pmap);
+retry:
 	oldpmap = pmap_switch(pmap);
 	pte = pmap_find_vhpt(addr);
 	if (pte != NULL) {
@@ -2192,53 +2217,27 @@ pmap_mincore(pmap_t pmap, vm_offset_t addr)
 		pte = &tpte;
 	}
 	pmap_switch(oldpmap);
-	PMAP_UNLOCK(pmap);
-
-	if (pte == NULL)
-		return 0;
-
-	if (pmap_present(pte)) {
-		vm_page_t m;
-		vm_offset_t pa;
-
-		val = MINCORE_INCORE;
-		if (!pmap_managed(pte))
-			return val;
-
+	if (pte == NULL || !pmap_present(pte)) {
+		val = 0;
+		goto out;
+	}
+	val = MINCORE_INCORE;
+	if (pmap_dirty(pte))
+		val |= MINCORE_MODIFIED | MINCORE_MODIFIED_OTHER;
+	if (pmap_accessed(pte))
+		val |= MINCORE_REFERENCED | MINCORE_REFERENCED_OTHER;
+	if ((val & (MINCORE_MODIFIED_OTHER | MINCORE_REFERENCED_OTHER)) !=
+	    (MINCORE_MODIFIED_OTHER | MINCORE_REFERENCED_OTHER) &&
+	    pmap_managed(pte)) {
 		pa = pmap_ppn(pte);
-
-		m = PHYS_TO_VM_PAGE(pa);
-
-		/*
-		 * Modified by us
-		 */
-		if (pmap_dirty(pte))
-			val |= MINCORE_MODIFIED|MINCORE_MODIFIED_OTHER;
-		else {
-			/*
-			 * Modified by someone
-			 */
-			vm_page_lock_queues();
-			if (pmap_is_modified(m))
-				val |= MINCORE_MODIFIED_OTHER;
-			vm_page_unlock_queues();
-		}
-		/*
-		 * Referenced by us
-		 */
-		if (pmap_accessed(pte))
-			val |= MINCORE_REFERENCED|MINCORE_REFERENCED_OTHER;
-		else {
-			/*
-			 * Referenced by someone
-			 */
-			vm_page_lock_queues();
-			if (pmap_is_referenced(m))
-				val |= MINCORE_REFERENCED_OTHER;
-			vm_page_unlock_queues();
-		}
-	} 
-	return val;
+		/* Ensure that "PHYS_TO_VM_PAGE(pa)->object" doesn't change. */
+		if (vm_page_pa_tryrelock(pmap, pa, locked_pa))
+			goto retry;
+	} else
+out:
+		PA_UNLOCK_COND(*locked_pa);
+	PMAP_UNLOCK(pmap);
+	return (val);
 }
 
 void