diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 3025d0badb..69912e6a22 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7719,6 +7719,11 @@ StartupXLOG(void)
 	 * Update full_page_writes in shared memory and write an XLOG_FPW_CHANGE
 	 * record before resource manager writes cleanup WAL records or checkpoint
 	 * record is written.
+	 *
+	 * It is safe to check the shared full_page_writes without the lock,
+	 * because there is no concurrently running process able to update it.
+	 * The only other process able to update full_page_writes is the
+	 * checkpointer, still it is unable to do so until recovery finishes.
 	 */
 	Insert->fullPageWrites = lastFullPageWrites;
 	LocalSetXLogInsertAllowed();
@@ -9693,14 +9698,27 @@ XLogReportParameters(void)
  * Update full_page_writes in shared memory, and write an
  * XLOG_FPW_CHANGE record if necessary.
  *
- * Note: this function assumes there is no other process running
- * concurrently that could update it.
+ * Note: this can be called from the checkpointer, or the startup process
+ * at the end of recovery.  One could think that this routine should be
+ * careful with its lock handling, however this is a no-op for the
+ * checkpointer until the startup process marks the end of recovery,
+ * so only one of them can do the work of this routine at once.
  */
 void
 UpdateFullPageWrites(void)
 {
 	XLogCtlInsert *Insert = &XLogCtl->Insert;
 
+	/*
+	 * Check if recovery is still in progress before entering this critical
+	 * section, as some memory allocation could happen at the end of
+	 * recovery.  There is nothing to do for a system still in recovery.
+	 * Note that we need to process things here at the end of recovery for
+	 * the startup process, which is why this checks after InRecovery.
+	 */
+	if (RecoveryInProgress() && !InRecovery)
+		return;
+
 	/*
 	 * Do nothing if full_page_writes has not been changed.
 	 *
@@ -9731,7 +9749,7 @@ UpdateFullPageWrites(void)
 	 * Write an XLOG_FPW_CHANGE record. This allows us to keep track of
 	 * full_page_writes during archive recovery, if required.
 	 */
-	if (XLogStandbyInfoActive() && !RecoveryInProgress())
+	if (XLogStandbyInfoActive())
 	{
 		XLogBeginInsert();
 		XLogRegisterData((char *) (&fullPageWrites), sizeof(bool));