Index: sys/dev/iscsi/iscsi_ioctl.c
===================================================================
RCS file: /cvsroot/src/sys/dev/iscsi/iscsi_ioctl.c,v
retrieving revision 1.30
diff -u -r1.30 iscsi_ioctl.c
--- sys/dev/iscsi/iscsi_ioctl.c	7 Dec 2018 14:59:19 -0000	1.30
+++ sys/dev/iscsi/iscsi_ioctl.c	15 May 2020 16:31:15 -0000
@@ -1308,7 +1308,7 @@
 	if ((p->p_sflag & PS_WEXIT) || (p->p_vmspace->vm_refcnt < 1)) {
 		return ISCSI_STATUS_NO_RESOURCES;
 	}
-	p->p_vmspace->vm_refcnt++;
+	uvmspace_addref(p->p_vmspace);
 
 	/* this is lifted from uvm_io */
 	error = uvm_map_extract(&p->p_vmspace->vm_map, databuf, datalen,
Index: sys/kern/kern_proc.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kern_proc.c,v
retrieving revision 1.251
diff -u -r1.251 kern_proc.c
--- sys/kern/kern_proc.c	29 Apr 2020 01:52:26 -0000	1.251
+++ sys/kern/kern_proc.c	15 May 2020 16:31:27 -0000
@@ -1719,7 +1719,7 @@
 	/* curproc exception is for coredump. */
 
 	if ((p != curproc && (p->p_sflag & PS_WEXIT) != 0) ||
-	    (p->p_vmspace->vm_refcnt < 1)) { /* XXX */
+	    (p->p_vmspace->vm_refcnt < 1)) {
 		return EFAULT;
 	}
 
Index: sys/kern/sys_process.c
===================================================================
RCS file: /cvsroot/src/sys/kern/sys_process.c,v
retrieving revision 1.179
diff -u -r1.179 sys_process.c
--- sys/kern/sys_process.c	13 Apr 2017 07:58:45 -0000	1.179
+++ sys/kern/sys_process.c	15 May 2020 16:31:27 -0000
@@ -168,12 +168,10 @@
 
 	vm = p->p_vmspace;
 
-	mutex_enter(&vm->vm_map.misc_lock);
 	if ((l->l_flag & LW_WEXIT) || vm->vm_refcnt < 1)
 		error = EFAULT;
 	if (error == 0)
-		p->p_vmspace->vm_refcnt++;  /* XXX */
-	mutex_exit(&vm->vm_map.misc_lock);
+		uvmspace_addref(p->p_vmspace);
 	if (error != 0)
 		return error;
 	error = uvm_io(&vm->vm_map, uio, pax_mprotect_prot(l));
Index: sys/uvm/uvm_extern.h
===================================================================
RCS file: /cvsroot/src/sys/uvm/uvm_extern.h,v
retrieving revision 1.226
diff -u -r1.226 uvm_extern.h
--- sys/uvm/uvm_extern.h	9 May 2020 15:13:19 -0000	1.226
+++ sys/uvm/uvm_extern.h	15 May 2020 16:31:41 -0000
@@ -566,8 +566,7 @@
  */
 struct vmspace {
 	struct	vm_map vm_map;	/* VM address map */
-	int	vm_refcnt;	/* number of references *
-				 * note: protected by vm_map.misc_lock */
+	volatile int vm_refcnt;	/* number of references */
 	void *	vm_shm;		/* SYS5 shared memory private data XXX */
 /* we copy from vm_startcopy to the end of the structure on fork */
 #define vm_startcopy vm_rssize
Index: sys/uvm/uvm_map.h
===================================================================
RCS file: /cvsroot/src/sys/uvm/uvm_map.h,v
retrieving revision 1.79
diff -u -r1.79 uvm_map.h
--- sys/uvm/uvm_map.h	14 Mar 2020 14:15:43 -0000	1.79
+++ sys/uvm/uvm_map.h	15 May 2020 16:31:41 -0000
@@ -220,7 +220,7 @@
 	struct vm_map_entry	header;		/* List of entries */
 	int			nentries;	/* Number of entries */
 	vsize_t			size;		/* virtual size */
-	int			ref_count;	/* Reference count */
+	volatile int		ref_count;	/* Reference count */
 	struct vm_map_entry *	hint;		/* hint for quick lookups */
 	struct vm_map_entry *	first_free;	/* First free space hint */
 	unsigned int		timestamp;	/* Version number */