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Index: head/sys/vm/vm_map.c
===================================================================
--- head/sys/vm/vm_map.c
+++ head/sys/vm/vm_map.c
@@ -1644,16 +1644,25 @@
}
}
+/*
+ * A map entry with any of the following flags set must not be merged with
+ * another entry.
+ */
+#define MAP_ENTRY_NOMERGE_MASK (MAP_ENTRY_GROWS_DOWN | MAP_ENTRY_GROWS_UP | \
+ MAP_ENTRY_IN_TRANSITION | MAP_ENTRY_IS_SUB_MAP)
+
static bool
vm_map_mergeable_neighbors(vm_map_entry_t prev, vm_map_entry_t entry)
{
- vm_size_t prevsize;
- prevsize = prev->end - prev->start;
+ KASSERT((prev->eflags & MAP_ENTRY_NOMERGE_MASK) == 0 ||
+ (entry->eflags & MAP_ENTRY_NOMERGE_MASK) == 0,
+ ("vm_map_mergeable_neighbors: neither %p nor %p are mergeable",
+ prev, entry));
return (prev->end == entry->start &&
prev->object.vm_object == entry->object.vm_object &&
(prev->object.vm_object == NULL ||
- prev->offset + prevsize == entry->offset) &&
+ prev->offset + (prev->end - prev->start) == entry->offset) &&
prev->eflags == entry->eflags &&
prev->protection == entry->protection &&
prev->max_protection == entry->max_protection &&
@@ -1667,18 +1676,14 @@
{
/*
- * If the backing object is a vnode object,
- * vm_object_deallocate() calls vrele().
- * However, vrele() does not lock the vnode
- * because the vnode has additional
- * references. Thus, the map lock can be kept
- * without causing a lock-order reversal with
- * the vnode lock.
+ * If the backing object is a vnode object, vm_object_deallocate()
+ * calls vrele(). However, vrele() does not lock the vnode because
+ * the vnode has additional references. Thus, the map lock can be
+ * kept without causing a lock-order reversal with the vnode lock.
*
- * Since we count the number of virtual page
- * mappings in object->un_pager.vnp.writemappings,
- * the writemappings value should not be adjusted
- * when the entry is disposed of.
+ * Since we count the number of virtual page mappings in
+ * object->un_pager.vnp.writemappings, the writemappings value
+ * should not be adjusted when the entry is disposed of.
*/
if (entry->object.vm_object != NULL)
vm_object_deallocate(entry->object.vm_object);
@@ -1704,10 +1709,8 @@
{
vm_map_entry_t next, prev;
- if ((entry->eflags & (MAP_ENTRY_GROWS_DOWN | MAP_ENTRY_GROWS_UP |
- MAP_ENTRY_IN_TRANSITION | MAP_ENTRY_IS_SUB_MAP)) != 0)
+ if ((entry->eflags & MAP_ENTRY_NOMERGE_MASK) != 0)
return;
-
prev = entry->prev;
if (vm_map_mergeable_neighbors(prev, entry)) {
vm_map_entry_unlink(map, prev);
@@ -1717,7 +1720,6 @@
vm_map_entry_resize_free(map, entry->prev);
vm_map_merged_neighbor_dispose(map, prev);
}
-
next = entry->next;
if (vm_map_mergeable_neighbors(entry, next)) {
vm_map_entry_unlink(map, next);
@@ -1726,6 +1728,7 @@
vm_map_merged_neighbor_dispose(map, next);
}
}
+
/*
* vm_map_clip_start: [ internal use only ]
*

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