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Lock one of the vm objects involved in an optimized copy-on-write fault.

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This commit is contained in:
Alan Cox 2003-06-21 06:31:42 +00:00
parent ce4d8747fa
commit ebf7512532
1 changed files with 5 additions and 2 deletions
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7
sys/vm/vm_fault.c
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@ -196,7 +196,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
int fault_flags)
{
vm_prot_t prot;
int result;
int is_first_object_locked, result;
boolean_t growstack, wired;
int map_generation;
vm_object_t next_object;
@ -683,6 +683,7 @@ readrest:
* dirty in the first object so that it will go out
* to swap when needed.
*/
is_first_object_locked = FALSE;
if (
/*
* Only one shadow object
@ -701,6 +702,7 @@ readrest:
*/
((fs.object->type == OBJT_DEFAULT) ||
(fs.object->type == OBJT_SWAP)) &&
(is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) &&
/*
* We don't chase down the shadow chain
*/
@ -730,7 +732,8 @@ readrest:
*/
vm_page_copy(fs.m, fs.first_m);
}
if (is_first_object_locked)
/*XXX*/ VM_OBJECT_UNLOCK(fs.first_object);
if (fs.m) {
/*
* We no longer need the old page or object.