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, 40 insertions, 12 deletions

diff --git a/sys/sparc64/sparc64/pmap.c b/sys/sparc64/sparc64/pmap.c
index 1524a1e..6b4ae41 100644
--- a/sys/sparc64/sparc64/pmap.c
+++ b/sys/sparc64/sparc64/pmap.c
@@ -1898,17 +1898,32 @@ boolean_t
 pmap_is_modified(vm_page_t m)
 {
 	struct tte *tp;
+	boolean_t rv;
 
-	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
-	if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) != 0)
-		return (FALSE);
+	KASSERT((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0,
+	    ("pmap_is_modified: page %p is not managed", m));
+	rv = FALSE;
+
+	/*
+	 * 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 TTEs can have TD_W set.
+	 */
+	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(tp, &m->md.tte_list, tte_link) {
 		if ((tp->tte_data & TD_PV) == 0)
 			continue;
-		if ((tp->tte_data & TD_W) != 0)
-			return (TRUE);
+		if ((tp->tte_data & TD_W) != 0) {
+			rv = TRUE;
+			break;
+		}
 	}
-	return (FALSE);
+	vm_page_unlock_queues();
+	return (rv);
 }
 
 /*
@@ -1951,9 +1966,20 @@ pmap_clear_modify(vm_page_t m)
 	struct tte *tp;
 	u_long data;
 
-	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
-	if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) != 0)
+	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 TTEs can have TD_W set.
+	 * 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(tp, &m->md.tte_list, tte_link) {
 		if ((tp->tte_data & TD_PV) == 0)
 			continue;
@@ -1961,6 +1987,7 @@ pmap_clear_modify(vm_page_t m)
 		if ((data & TD_W) != 0)
 			tlb_page_demap(TTE_GET_PMAP(tp), TTE_GET_VA(tp));
 	}
+	vm_page_unlock_queues();
 }
 
 void
@@ -1969,9 +1996,9 @@ pmap_clear_reference(vm_page_t m)
 	struct tte *tp;
 	u_long data;
 
-	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
-	if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) != 0)
-		return;
+	KASSERT((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0,
+	    ("pmap_clear_reference: page %p is not managed", m));
+	vm_page_lock_queues();
 	TAILQ_FOREACH(tp, &m->md.tte_list, tte_link) {
 		if ((tp->tte_data & TD_PV) == 0)
 			continue;
@@ -1979,6 +2006,7 @@ pmap_clear_reference(vm_page_t m)
 		if ((data & TD_REF) != 0)
 			tlb_page_demap(TTE_GET_PMAP(tp), TTE_GET_VA(tp));
 	}
+	vm_page_unlock_queues();
 }
 
 void
@@ -2014,7 +2042,7 @@ pmap_remove_write(vm_page_t m)
 }
 
 int
-pmap_mincore(pmap_t pm, vm_offset_t addr)
+pmap_mincore(pmap_t pm, vm_offset_t addr, vm_paddr_t *locked_pa)
 {
 
 	/* TODO; */