Author: Filip Januš <fjanus@redhat.com>
Date: 6 Sep 2021
Related: https://bugzilla.redhat.com/show_bug.cgi?id=1992402

diff -ur db-5.3.28/src/os/os_map.c db-patched/src/os/os_map.c
--- db-5.3.28/src/os/os_map.c	2013-09-09 17:35:09.000000000 +0200
+++ db-patched/src/os/os_map.c	2021-09-06 14:32:28.792139908 +0200
@@ -213,6 +213,10 @@
 	if (rp->max < rp->size)
 		rp->max = rp->size;
 	if (ret == 0 && F_ISSET(infop, REGION_CREATE)) {
+#ifdef HAVE_MLOCK
+        if (F_ISSET(env, ENV_LOCKDOWN))
+            rp->size = rp->max;
+#endif
 		if (F_ISSET(dbenv, DB_ENV_REGION_INIT))
 			ret = __db_file_write(env, infop->fhp,
 			    rp->size / MEGABYTE, rp->size % MEGABYTE, 0x00);