Index: sys/compat/linprocfs/linprocfs.c
===================================================================
--- sys/compat/linprocfs/linprocfs.c
+++ sys/compat/linprocfs/linprocfs.c
@@ -1978,6 +1978,21 @@
 	return (0);
 }
 
+/*
+ * Filler function for proc/sys/vm/max_map_count
+ *
+ * Maximum number of active map areas, on Linux this limits the number
+ * of vmaps per mm struct. We don't limit mappings, return a suitable
+ * large value.
+ */
+static int
+linprocfs_domax_map_cnt(PFS_FILL_ARGS)
+{
+
+	sbuf_printf(sb, "%d\n", INT32_MAX);
+	return (0);
+}
+
 /*
  * Constructor
  */
@@ -2123,6 +2138,8 @@
 	dir = pfs_create_dir(sys, "vm", NULL, NULL, NULL, 0);
 	pfs_create_file(dir, "min_free_kbytes", &linprocfs_dominfree,
 	    NULL, NULL, NULL, PFS_RD);
+	pfs_create_file(dir, "max_map_count", &linprocfs_domax_map_cnt,
+	    NULL, NULL, NULL, PFS_RD);
 
 	return (0);
 }