diff options
| -rw-r--r-- | sys/vm/vm_object.c | 31 |
1 files changed, 25 insertions, 6 deletions
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c index 66ec1e9..a8ed619 100644 --- a/sys/vm/vm_object.c +++ b/sys/vm/vm_object.c @@ -1833,10 +1833,22 @@ vm_object_collapse(vm_object_t object) /* * vm_object_page_remove: * - * Removes all physical pages in the given range from the - * object's list of pages. If the range's end is zero, all - * physical pages from the range's start to the end of the object - * are deleted. + * For the given object, either frees or invalidates each of the + * specified pages. In general, a page is freed. However, if a + * page is wired for any reason other than the existence of a + * managed, wired mapping, then it may be invalidated but not + * removed from the object. Pages are specified by the given + * range ["start", "end") and Boolean "clean_only". As a + * special case, if "end" is zero, then the range extends from + * "start" to the end of the object. If "clean_only" is TRUE, + * then only the non-dirty pages within the specified range are + * affected. + * + * In general, this operation should only be performed on objects + * that contain managed pages. There are two exceptions. First, + * it may be performed on the kernel and kmem objects. Second, + * it may be used by msync(..., MS_INVALIDATE) to invalidate + * device-backed pages. * * The object must be locked. */ @@ -1883,11 +1895,16 @@ again: /* * If the page is wired for any reason besides the * existence of managed, wired mappings, then it cannot - * be freed. + * be freed. For example, fictitious pages, which + * represent device memory, are inherently wired and + * cannot be freed. They can, however, be invalidated + * if "clean_only" is FALSE. */ if ((wirings = p->wire_count) != 0 && (wirings = pmap_page_wired_mappings(p)) != p->wire_count) { - pmap_remove_all(p); + /* Fictitious pages do not have managed mappings. */ + if ((p->flags & PG_FICTITIOUS) == 0) + pmap_remove_all(p); /* Account for removal of managed, wired mappings. */ p->wire_count -= wirings; if (!clean_only) @@ -1896,6 +1913,8 @@ again: } if (vm_page_sleep_if_busy(p, TRUE, "vmopar")) goto again; + KASSERT((p->flags & PG_FICTITIOUS) == 0, + ("vm_object_page_remove: page %p is fictitious", p)); if (clean_only && p->valid) { pmap_remove_write(p); if (p->valid & p->dirty) |
