From: Martin Pieuchot <mpi@grenadille.net>
Subject: pgo_reference vs KERNEL_LOCK()
To: tech@openbsd.org
Date: Sat, 2 Nov 2024 21:40:11 +0100

Since page faults are executed in parallel, all pgo_reference()
implementations are safe to be executed w/o KERNEL_LOCK().

ok?

Index: uvm/uvm_map.c
===================================================================
RCS file: /cvs/src/sys/uvm/uvm_map.c,v
diff -u -p -r1.333 uvm_map.c
--- uvm/uvm_map.c	31 Oct 2024 05:00:00 -0000	1.333
+++ uvm/uvm_map.c	2 Nov 2024 20:35:23 -0000
@@ -2593,10 +2593,8 @@ uvm_map_splitentry(struct vm_map *map, s
 		} else if (UVM_ET_ISOBJ(orig)) {
 			if (next->object.uvm_obj->pgops &&
 			    next->object.uvm_obj->pgops->pgo_reference) {
-				KERNEL_LOCK();
 				next->object.uvm_obj->pgops->pgo_reference(
 				    next->object.uvm_obj);
-				KERNEL_UNLOCK();
 			}
 			next->offset += adj;
 		}