Index: sys/fs/nfsclient/nfs_clport.c
===================================================================
--- sys/fs/nfsclient/nfs_clport.c
+++ sys/fs/nfsclient/nfs_clport.c
@@ -99,6 +99,7 @@
 
 static void nfscl_warn_fileid(struct nfsmount *, struct nfsvattr *,
     struct nfsvattr *);
+static struct proc *nfscl_pfind(pid_t);
 
 /*
  * Comparison function for vfs_hash functions.
@@ -1131,6 +1132,36 @@
 }
 
 /*
+ * This is a variant of _pfind() that can only be called when all pid hash
+ * lists are locked.  It must be done this way, since nfscl_procdoesntexist()
+ * must be called with locked mutexes and the sx locks for the hash lists
+ * must be acquired before the mutexes.
+ * It will return Zombie processes.
+ */
+static struct proc *
+nfscl_pfind(pid_t pid)
+{
+	struct proc *p;
+
+	p = curproc;
+	if (p->p_pid == pid) {
+		PROC_LOCK(p);
+		return (p);
+	}
+	LIST_FOREACH(p, PIDHASH(pid), p_hash) {
+		if (p->p_pid == pid) {
+			PROC_LOCK(p);
+			if (p->p_state == PRS_NEW) {
+				PROC_UNLOCK(p);
+				p = NULL;
+			}
+			break;
+		}
+	}
+	return (p);
+}
+
+/*
  * Check to see if the process for this owner exists. Return 1 if it doesn't
  * and 0 otherwise.
  */
@@ -1157,7 +1188,7 @@
 	tl.cval[2] = *own++;
 	tl.cval[3] = *own++;
 	pid = tl.lval;
-	p = pfind(pid);
+	p = nfscl_pfind(pid);
 	if (p == NULL)
 		return (1);
 	if (p->p_stats == NULL) {
Index: sys/fs/nfsclient/nfs_clstate.c
===================================================================
--- sys/fs/nfsclient/nfs_clstate.c
+++ sys/fs/nfsclient/nfs_clstate.c
@@ -1788,8 +1788,16 @@
 	struct nfsclopen *op;
 	struct nfscllockowner *lp, *nlp;
 	struct nfscldeleg *dp;
+	int i;
 
-	NFSPROCLISTLOCK();
+	/*
+	 * All the pidhash locks must be acquired, since they are sx locks
+	 * and must be acquired before the mutexes.  The pid(s) that will
+	 * be used aren't known yet, so all the locks need to be acquired.
+	 * Fortunately, this function is only performed once/sec.
+	 */
+	for (i = 0; i < pidhashlock + 1; i++)
+		sx_slock(&pidhashtbl_lock[i]);
 	NFSLOCKCLSTATE();
 	LIST_FOREACH_SAFE(owp, &clp->nfsc_owner, nfsow_list, nowp) {
 		LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
@@ -1816,7 +1824,8 @@
 		}
 	}
 	NFSUNLOCKCLSTATE();
-	NFSPROCLISTUNLOCK();
+	for (i = 0; i < pidhashlock + 1; i++)
+		sx_sunlock(&pidhashtbl_lock[i]);
 }
 
 /*
Index: sys/kern/kern_proc.c
===================================================================
--- sys/kern/kern_proc.c
+++ sys/kern/kern_proc.c
@@ -178,6 +178,7 @@
 procinit(void)
 {
 	u_long i;
+	char buf[16];
 
 	sx_init(&allproc_lock, "allproc");
 	sx_init(&zombproc_lock, "zombproc");
@@ -192,8 +193,10 @@
 		pidhashlock--;
 	pidhashtbl_lock = malloc(sizeof(*pidhashtbl_lock) * (pidhashlock + 1),
 	    M_PROC, M_WAITOK | M_ZERO);
-	for (i = 0; i < pidhashlock + 1; i++)
-		sx_init(&pidhashtbl_lock[i], "pidhash");
+	for (i = 0; i < pidhashlock + 1; i++) {
+		snprintf(buf, sizeof(buf), "pidhash%ju", (uintmax_t)i);
+		sx_init(&pidhashtbl_lock[i], buf);
+	}
 	pgrphashtbl = hashinit(maxproc / 4, M_PROC, &pgrphash);
 	proc_zone = uma_zcreate("PROC", sched_sizeof_proc(),
 	    proc_ctor, proc_dtor, proc_init, proc_fini,