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Index: head/sys/vm/vm_map.c
===================================================================
--- head/sys/vm/vm_map.c
+++ head/sys/vm/vm_map.c
@@ -2454,6 +2454,7 @@
vm_object_t obj;
struct ucred *cred;
vm_prot_t old_prot;
+ int rv;
if (start == end)
return (KERN_SUCCESS);
@@ -2508,10 +2509,13 @@
}
/*
- * Do an accounting pass for private read-only mappings that
- * now will do cow due to allowed write (e.g. debugger sets
- * breakpoint on text segment)
+ * Before changing the protections, try to reserve swap space for any
+ * private (i.e., copy-on-write) mappings that are transitioning from
+ * read-only to read/write access. If a reservation fails, break out
+ * of this loop early and let the next loop simplify the entries, since
+ * some may now be mergeable.
*/
+ rv = KERN_SUCCESS;
vm_map_clip_start(map, entry, start);
for (current = entry; current->start < end; current = current->next) {
@@ -2529,8 +2533,9 @@
if (obj == NULL || (current->eflags & MAP_ENTRY_NEEDS_COPY)) {
if (!swap_reserve(current->end - current->start)) {
- vm_map_unlock(map);
- return (KERN_RESOURCE_SHORTAGE);
+ rv = KERN_RESOURCE_SHORTAGE;
+ end = current->end;
+ break;
}
crhold(cred);
current->cred = cred;
@@ -2553,8 +2558,9 @@
obj, current));
if (!swap_reserve(ptoa(obj->size))) {
VM_OBJECT_WUNLOCK(obj);
- vm_map_unlock(map);
- return (KERN_RESOURCE_SHORTAGE);
+ rv = KERN_RESOURCE_SHORTAGE;
+ end = current->end;
+ break;
}
crhold(cred);
@@ -2564,11 +2570,14 @@
}
/*
- * Go back and fix up protections. [Note that clipping is not
- * necessary the second time.]
+ * If enough swap space was available, go back and fix up protections.
+ * Otherwise, just simplify entries, since some may have been modified.
+ * [Note that clipping is not necessary the second time.]
*/
- for (current = entry; current->start < end; current = current->next) {
- if ((current->eflags & MAP_ENTRY_GUARD) != 0)
+ for (current = entry; current->start < end;
+ vm_map_simplify_entry(map, current), current = current->next) {
+ if (rv != KERN_SUCCESS ||
+ (current->eflags & MAP_ENTRY_GUARD) != 0)
continue;
old_prot = current->protection;
@@ -2603,10 +2612,9 @@
current->protection & MASK(current));
#undef MASK
}
- vm_map_simplify_entry(map, current);
}
vm_map_unlock(map);
- return (KERN_SUCCESS);
+ return (rv);
}
/*

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