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, 22 insertions, 1 deletions

diff --git a/sys/arm/arm/pmap.c b/sys/arm/arm/pmap.c
index 00d499f..2532a5b 100644
--- a/sys/arm/arm/pmap.c
+++ b/sys/arm/arm/pmap.c
@@ -4475,6 +4475,8 @@ boolean_t
 pmap_is_modified(vm_page_t m)
 {
 
+	KASSERT((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0,
+	    ("pmap_is_modified: page %p is not managed", m));
 	if (m->md.pvh_attrs & PVF_MOD)
 		return (TRUE);
 	
@@ -4489,8 +4491,23 @@ void
 pmap_clear_modify(vm_page_t m)
 {
 
+	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 mappings 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();
 	if (m->md.pvh_attrs & PVF_MOD)
 		pmap_clearbit(m, PVF_MOD);
+	vm_page_unlock_queues();
 }
 
 
@@ -4517,8 +4534,12 @@ void
 pmap_clear_reference(vm_page_t m)
 {
 
+	KASSERT((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0,
+	    ("pmap_clear_reference: page %p is not managed", m));
+	vm_page_lock_queues();
 	if (m->md.pvh_attrs & PVF_REF) 
 		pmap_clearbit(m, PVF_REF);
+	vm_page_unlock_queues();
 }
 
 
@@ -4551,7 +4572,7 @@ pmap_remove_write(vm_page_t m)
  * 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)
 {
 	printf("pmap_mincore()\n");