Index: sys/compat/svr4/svr4_misc.c
===================================================================
RCS file: /usr/cvs/src/sys/compat/svr4/svr4_misc.c,v
retrieving revision 1.42
diff -u -r1.42 svr4_misc.c
--- sys/compat/svr4/svr4_misc.c	2002/03/20 10:32:01	1.42
+++ sys/compat/svr4/svr4_misc.c	2002/04/27 03:01:42
@@ -1330,8 +1330,14 @@
 			/*
 			 * Remove unused arguments
 			 */
-			if (q->p_args && --q->p_args->ar_ref == 0)
-				FREE(q->p_args, M_PARGS);
+			if (q->p_args) {
+				PARGS_LOCK();
+				if (--q->p_args->ar_ref == 0) {
+					PARGS_UNLOCK();
+					FREE(q->p_args, M_PARGS);
+				} else
+					PARGS_UNLOCK();
+			}
 			PROC_UNLOCK(q);
 
 			/*
Index: sys/kern/kern_exec.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/kern_exec.c,v
retrieving revision 1.156
diff -u -r1.156 kern_exec.c
--- sys/kern/kern_exec.c	2002/03/19 21:24:06	1.156
+++ sys/kern/kern_exec.c	2002/04/27 02:57:18
@@ -441,8 +441,14 @@
 	pa = p->p_args;
 	p->p_args = NULL;
 	PROC_UNLOCK(p);
-	if (pa != NULL && --pa->ar_ref == 0)
-		FREE(pa, M_PARGS);
+	if (pa != NULL) {
+		PARGS_LOCK();
+		if (--pa->ar_ref == 0) {
+			PARGS_UNLOCK();
+			FREE(pa, M_PARGS);
+		} else 
+			PARGS_UNLOCK();
+	}
 
 	/* Set values passed into the program in registers. */
 	setregs(td, imgp->entry_addr, (u_long)(uintptr_t)stack_base,
Index: sys/kern/kern_exit.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/kern_exit.c,v
retrieving revision 1.152
diff -u -r1.152 kern_exit.c
--- sys/kern/kern_exit.c	2002/03/20 04:09:58	1.152
+++ sys/kern/kern_exit.c	2002/04/27 03:16:16
@@ -637,8 +637,14 @@
 			/*
 			 * Remove unused arguments
 			 */
-			if (p->p_args && --p->p_args->ar_ref == 0)
-				FREE(p->p_args, M_PARGS);
+			if (p->p_args) {
+				PARGS_LOCK();
+				if (--p->p_args->ar_ref == 0) {
+					PARGS_UNLOCK();
+					FREE(p->p_args, M_PARGS);
+				} else
+					PARGS_UNLOCK();
+			}
 
 			if (--p->p_procsig->ps_refcnt == 0) {
 				if (p->p_sigacts != &p->p_uarea->u_sigacts)
Index: sys/kern/kern_fork.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/kern_fork.c,v
retrieving revision 1.139
diff -u -r1.139 kern_fork.c
--- sys/kern/kern_fork.c	2002/03/21 02:47:51	1.139
+++ sys/kern/kern_fork.c	2002/04/27 02:59:20
@@ -482,8 +482,11 @@
 	p2->p_ucred = crhold(p1->p_ucred);
 	td2->td_ucred = crhold(p2->p_ucred);	/* XXXKSE */
 
-	if (p2->p_args)
+	if (p2->p_args) {
+		PARGS_LOCK();
 		p2->p_args->ar_ref++;
+		PARGS_UNLOCK();
+	}
 
 	if (flags & RFSIGSHARE) {
 		p2->p_procsig = p1->p_procsig;
Index: sys/kern/kern_proc.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/kern_proc.c,v
retrieving revision 1.118
diff -u -r1.118 kern_proc.c
--- sys/kern/kern_proc.c	2002/03/24 05:09:11	1.118
+++ sys/kern/kern_proc.c	2002/04/27 04:07:16
@@ -80,6 +80,7 @@
 struct sx allproc_lock;
 struct sx proctree_lock;
 struct sx pgrpsess_lock;
+struct mtx pargs_ref_lock;
 uma_zone_t proc_zone;
 uma_zone_t ithread_zone;
 
@@ -94,6 +95,7 @@
 	sx_init(&allproc_lock, "allproc");
 	sx_init(&proctree_lock, "proctree");
 	sx_init(&pgrpsess_lock, "pgrpsess");
+	mtx_init(&pargs_ref_lock, "struct pargs.ref",MTX_DEF);
 	LIST_INIT(&allproc);
 	LIST_INIT(&zombproc);
 	pidhashtbl = hashinit(maxproc / 4, M_PROC, &pidhash);
@@ -982,8 +984,15 @@
 	pa = p->p_args;
 	p->p_args = NULL;
 	PROC_UNLOCK(p);
-	if (pa != NULL && --pa->ar_ref == 0) 
-		FREE(pa, M_PARGS);
+
+	PARGS_LOCK();
+	if (pa != NULL) {
+		if (--pa->ar_ref == 0) {
+			PARGS_UNLOCK();
+			FREE(pa, M_PARGS);
+		} else 
+			PARGS_UNLOCK();
+	}
 
 	if (req->newlen + sizeof(struct pargs) > ps_arg_cache_limit)
 		return (error);
Index: sys/sys/proc.h
===================================================================
RCS file: /usr/cvs/src/sys/sys/proc.h,v
retrieving revision 1.211
diff -u -r1.211 proc.h
--- sys/sys/proc.h	2002/03/20 21:09:09	1.211
+++ sys/sys/proc.h	2002/04/27 03:07:31
@@ -111,9 +111,9 @@
  * pargs, used to hold a copy of the command line, if it had a sane length.
  */
 struct pargs {
-	u_int	ar_ref;		/* Reference count. */
-	u_int	ar_length;	/* Length. */
-	u_char	ar_args[0];	/* Arguments. */
+	u_int		ar_ref;		/* Reference count. */
+	u_int		ar_length;	/* Length. */
+	u_char		ar_args[0];	/* Arguments. */
 };
 
 /*-
@@ -668,6 +668,10 @@
 	(--(p)->p_lock);						\
 } while (0)
 
+/* Lock and unlock the process arguments. */
+#define PARGS_LOCK()	mtx_lock(&pargs_ref_lock)
+#define PARGS_UNLOCK()	mtx_unlock(&pargs_ref_lock)
+
 #define	PIDHASH(pid)	(&pidhashtbl[(pid) & pidhash])
 extern LIST_HEAD(pidhashhead, proc) *pidhashtbl;
 extern u_long pidhash;
@@ -679,6 +683,7 @@
 extern struct sx allproc_lock;
 extern struct sx proctree_lock;
 extern struct sx pgrpsess_lock;
+extern struct mtx pargs_ref_lock;
 extern struct proc proc0;		/* Process slot for swapper. */
 extern struct thread thread0;		/* Primary thread in proc0 */
 extern int hogticks;			/* Limit on kernel cpu hogs. */