diff options
Diffstat (limited to 'sys/vm/vm_fault.c')
| -rw-r--r-- | sys/vm/vm_fault.c | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c index aba9ecf88fa3..c061c3eb6f12 100644 --- a/sys/vm/vm_fault.c +++ b/sys/vm/vm_fault.c @@ -66,7 +66,7 @@ * any improvements or extensions that they make and grant Carnegie the * rights to redistribute these changes. * - * $Id: vm_fault.c,v 1.23 1995/04/16 14:12:12 davidg Exp $ + * $Id: vm_fault.c,v 1.24 1995/05/18 02:59:22 davidg Exp $ */ /* @@ -221,27 +221,27 @@ RetryFault:; /* * INVARIANTS (through entire routine): - * + * * 1) At all times, we must either have the object lock or a busy * page in some object to prevent some other thread from trying to * bring in the same page. - * + * * Note that we cannot hold any locks during the pager access or when * waiting for memory, so we use a busy page then. - * + * * Note also that we aren't as concerned about more than one thead * attempting to pager_data_unlock the same page at once, so we don't * hold the page as busy then, but do record the highest unlock value * so far. [Unlock requests may also be delivered out of order.] - * + * * 2) Once we have a busy page, we must remove it from the pageout * queues, so that the pageout daemon will not grab it away. - * + * * 3) To prevent another thread from racing us down the shadow chain * and entering a new page in the top object before we do, we must * keep a busy page in the top object while following the shadow * chain. - * + * * 4) We must increment paging_in_progress on any object for which * we have a busy page, to prevent vm_object_collapse from removing * the busy page without our noticing. @@ -381,7 +381,7 @@ readrest: UNLOCK_AND_DEALLOCATE; goto RetryFault; } - + pmap_clear_modify(VM_PAGE_TO_PHYS(m)); m->valid = VM_PAGE_BITS_ALL; hardfault++; @@ -391,10 +391,10 @@ readrest: * Remove the bogus page (which does not exist at this * object/offset); before doing so, we must get back * our object lock to preserve our invariant. - * + * * Also wake up any other thread that may want to bring * in this page. - * + * * If this is the top-level object, we must leave the * busy page to prevent another thread from rushing * past us, and inserting the page in that object at @@ -501,11 +501,11 @@ readrest: * object locked). We can't unlock the bottom object, * because the page we found may move (by collapse) if * we do. - * + * * Instead, we first copy the page. Then, when we have * no more use for the bottom object, we unlock it and * try to collapse. - * + * * Note that we copy the page even if we didn't need * to... that's the breaks. */ @@ -523,7 +523,7 @@ readrest: * we have to flush all uses of the original page, * since we can't distinguish those which want the * original from those which need the new copy. - * + * * XXX If we know that only one map has access to this * page, then we could avoid the pmap_page_protect() * call. |