osfmk/vm/vm_object.c

117  *	Each object also records the memory object reference
257  *	The routines that acquire a reference to a virtual
262  *	from the reference mechanism, so that the lock need
696 	 * Create an "extra" reference to this object so that we never
759  *	Release a reference to the specified object,
809 		 * kept alive solely by the reference we're about to release.
810 		 * Let's try and release our reference without taking
861 		 *	If the object has a named reference, and only
862 		 *	that reference would remain, inform the pager
863 		 *	about the last "mapping" reference going away.
885 		 *	Lose the reference. If other references
888 		 *	If it is the last reference, then keep it
904 				 * There's only one reference left on this
916 				 * don't know if this last reference on it is
961 			 *	Now it is safe to decrement reference count,
962 			 *	and to return if reference count is > 0.
1077 			 *	but maintain a "paging reference" rather than
1078 			 *	a normal reference.
1135 				if (p->reference == FALSE || p->dirty == FALSE) {
1140 						p->reference = TRUE;
1150 						p->reference = TRUE;
1159 			if (p->inactive && p->reference == TRUE) {
1392 				p->reference = FALSE;
1526 		 *	Take a reference to avoid recursive deallocations.
1538 		 *	maintain a "paging reference" rather than a normal
1539 		 *	reference.
1565  *		and the object must have exactly one reference.
1567  *		The shadow object reference is left alone.
1608 	 * Did somebody get a reference to the object while we were
1639 	 *	copy. The reference we hold on the shadow must be dropped
1658 		 * they may also need to acquire a reference on the VM object,
1660 		 * they may end up releasing the last reference on the VM
1678 		 * object's reference on its shadow object yet.
1695 	 * reference on it.
1696 	 * The caller is responsible for dropping that reference.
1780 	 * release our reference to it here.
2119 			 * Drop the reference "object" was holding on
2170  *			release our last reference to it.
2196 	 *	Release reference to pager.
2261 		 * JMM - Release the caller's reference.  This assumes the
2262 		 * caller had a reference to release, which is a big (but
2264 		 * vnode pager (it is holding a named reference when making
2455 		 * We're already holding a "paging in progress" reference
3130  *		The caller must hold a reference and a lock
3184 	 *		 this routine, since we have the only reference.
3353 	 *	Lose the extra reference, and return our object.
3406 		 *	Make another reference to the object.
3574  *		on exit - so the caller must also hold a reference to it.
3698 			 *	Return another reference to
4007  *	object reference is deallocated.
4074 	 *	a reference to it.  Our caller changes his reference
4075 	 *	to point to the new object, removing a reference to
4076 	 *	the source object.  Net result: no change of reference
4109  *			a port reference;
4167  *	During various paging operations, the pager reference found in the
4336 		 *	Copy the reference we were given.
4432 	 *	Prevent collapse or termination by holding a paging reference
4488 		/* acquire a reference for the default memory manager */
4508 	 *	A reference was returned by
4517 	 *	Drop the reference we were passed.
4524 	 *	Release the paging reference
4540 	 *	Prevent collapse or termination by holding a paging reference
4607 	 *	A reference was returned by
4616 	 *	Drop the reference we were passed.
4623 	 *	Release the paging reference
4857 	 *	Note that the reference to backing_object->shadow
4914 	 *	Do object reference in-line to
4951 	 *	Drop the reference count on backing_object.
4993 			/* XXX get a reference for the deallocate below */
5000 		 * valid reference is held on the object... w/o a valid
5001 		 * reference, it is unsafe and unwise (you will definitely
5004 		 * The "activity_in_progress" reference will keep the object
5167 		 *	object (if the parent is the only reference to
5168 		 *	it) or (perhaps) remove the parent's reference
5171 		 *	If there is exactly one reference to the backing
5561  *		prev_size	Size of reference to prev_object
5562  *		next_size	Size of reference to next_object
5566  *	to preserve the reference to the object(s).
5607 	 *	. more than one reference
5860 			*	(implicit) reference. Take a reference to avoid
5874 		 	*	maintain a "paging reference" rather
5875 			*	than a normal reference.
5946  *		Attempt to recover a named reference for a VM object.
5951  *		KERN_SUCCESS - we recovered a named reference on the object
5952  *		KERN_FAILURE - we could not recover a reference (object dead)
6020  *	Enforces name semantic on memory_object reference count decrement
6022  *	reference gained through the memory_object_create_named.
6025  *	reference count is not 1. i.e. idle with the only remaining reference
6028  *	false and the reference count is decremented.  If the RESPECT_CACHE
6029  *	flag is set and the reference count has gone to zero, the
6031  *	the reference count is zero, it is simply terminated.
6151 	 *	Lock the object, and acquire a paging reference to
6152 	 *	prevent the memory_object reference from being released.
6220  * special semantics when its reference count is exactly 1.  If its reference
6735  *	Gets another reference to the given object.
6853 	 * taking a "paging_in_progress" reference wouldn't be enough