diff --git a/.topdeps b/.topdeps
new file mode 100644
index 0000000000..1f7391f92b
--- /dev/null
+++ b/.topdeps
@@ -0,0 +1 @@
+master
diff --git a/.topmsg b/.topmsg
new file mode 100644
index 0000000000..9ae8bcda7d
--- /dev/null
+++ b/.topmsg
@@ -0,0 +1,8 @@
+From: Brian Behlendorf <behlendorf1@llnl.gov>
+Subject: [PATCH] fix stack vn_open
+
+We should not put a 4k maxpathlen buffer on the stack, instead
+locate it to the heap.  Even in user space we run ztest with 8K
+stacks to verify correctness
+
+Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
diff --git a/lib/libzpool/kernel.c b/lib/libzpool/kernel.c
index 5284c12532..89c8975846 100644
--- a/lib/libzpool/kernel.c
+++ b/lib/libzpool/kernel.c
@@ -327,9 +327,11 @@ vn_open(char *path, int x1, int flags, int mode, vnode_t **vpp, int x2, int x3)
 	int fd;
 	vnode_t *vp;
 	int old_umask;
-	char realpath[MAXPATHLEN];
+	char *realpath;
 	struct stat64 st;
 
+	realpath = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
+
 	/*
 	 * If we're accessing a real disk from userland, we need to use
 	 * the character interface to avoid caching.  This is particularly
@@ -343,11 +345,16 @@ vn_open(char *path, int x1, int flags, int mode, vnode_t **vpp, int x2, int x3)
 	if (strncmp(path, "/dev/", 5) == 0) {
 		char *dsk;
 		fd = open64(path, O_RDONLY);
-		if (fd == -1)
-			return (errno);
+		if (fd == -1) {
+			err = errno;
+			free(realpath);
+			return (err);
+		}
 		if (fstat64(fd, &st) == -1) {
+			err = errno;
 			close(fd);
-			return (errno);
+			free(realpath);
+			return (err);
 		}
 		close(fd);
 		(void) sprintf(realpath, "%s", path);
@@ -357,8 +364,11 @@ vn_open(char *path, int x1, int flags, int mode, vnode_t **vpp, int x2, int x3)
 			    dsk + 1);
 	} else {
 		(void) sprintf(realpath, "%s", path);
-		if (!(flags & FCREAT) && stat64(realpath, &st) == -1)
-			return (errno);
+		if (!(flags & FCREAT) && stat64(realpath, &st) == -1) {
+			err = errno;
+			free(realpath);
+			return (err);
+		}
 	}
 
 	if (flags & FCREAT)
@@ -369,6 +379,7 @@ vn_open(char *path, int x1, int flags, int mode, vnode_t **vpp, int x2, int x3)
 	 * FREAD and FWRITE to the corresponding O_RDONLY, O_WRONLY, and O_RDWR.
 	 */
 	fd = open64(realpath, flags - FREAD, mode);
+	free(realpath);
 
 	if (flags & FCREAT)
 		(void) umask(old_umask);