diff options
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/vm/vm_object.c | 33 |
1 files changed, 30 insertions, 3 deletions
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c index 68dc28e46cb..0fa0d2e92c4 100644 --- a/sys/vm/vm_object.c +++ b/sys/vm/vm_object.c @@ -1,4 +1,4 @@ -/* $OpenBSD: vm_object.c,v 1.11 1996/08/19 10:38:01 niklas Exp $ */ +/* $OpenBSD: vm_object.c,v 1.12 1996/11/06 23:24:40 niklas Exp $ */ /* $NetBSD: vm_object.c,v 1.34 1996/02/28 22:35:35 gwr Exp $ */ /* @@ -1299,7 +1299,12 @@ vm_object_collapse_aux(object) /* * Second, start paging it in. If this * fails, what can we do but punt? + * Even though the shadowing object + * isn't exactly paging we say so in + * order to not get simultaneous + * cascaded collapses. */ + object->paging_in_progress++; backing_object->paging_in_progress++; if (vm_pager_get_pages(backing_object->pager, &backing_page, 1, TRUE) != VM_PAGER_OK) { @@ -1310,8 +1315,30 @@ vm_object_collapse_aux(object) return KERN_FAILURE; } cnt.v_pgpgin++; - if (--backing_object->paging_in_progress == 0) - thread_wakeup(backing_object); + + /* + * A fault might have issued other + * pagein operations. We must wait for + * them to complete, then we get to + * wakeup potential other waiters as + * well. + */ + while (backing_object->paging_in_progress != 1 + || object->paging_in_progress != 1) { + if (object->paging_in_progress != 1) { + vm_object_sleep(object, object, + FALSE); + vm_object_lock(object); + continue; + } + vm_object_sleep(backing_object, + backing_object, FALSE); + vm_object_lock(backing_object); + } + backing_object->paging_in_progress--; + object->paging_in_progress--; + thread_wakeup(backing_object); + thread_wakeup(object); /* * Third, relookup in case pager changed |