diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index f7a15a21467..abfad07d5e4 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -368,8 +368,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				stack->next = ptr;
 			}
 		}
-		LockBuffer(buffer, GIN_UNLOCK);
-		ReleaseBuffer(buffer);
+		UnlockReleaseBuffer(buffer);
 
 		/* Step to next item in the queue */
 		stack_next = stack->next;
@@ -642,8 +641,7 @@ gin_check_parent_keys_consistency(Relation rel,
 			prev_attnum = current_attnum;
 		}
 
-		LockBuffer(buffer, GIN_UNLOCK);
-		ReleaseBuffer(buffer);
+		UnlockReleaseBuffer(buffer);
 
 		/* Step to next item in the queue */
 		stack_next = stack->next;
diff --git a/contrib/pageinspect/rawpage.c b/contrib/pageinspect/rawpage.c
index 86fe245cac5..f3996dc39fc 100644
--- a/contrib/pageinspect/rawpage.c
+++ b/contrib/pageinspect/rawpage.c
@@ -193,8 +193,7 @@ get_raw_page_internal(text *relname, ForkNumber forknum, BlockNumber blkno)
 
 	memcpy(raw_page_data, BufferGetPage(buf), BLCKSZ);
 
-	LockBuffer(buf, BUFFER_LOCK_UNLOCK);
-	ReleaseBuffer(buf);
+	UnlockReleaseBuffer(buf);
 
 	relation_close(rel, AccessShareLock);
 
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 044f385e477..eb1f67f31cd 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -1697,8 +1697,7 @@ heap_fetch(Relation relation,
 	offnum = ItemPointerGetOffsetNumber(tid);
 	if (offnum < FirstOffsetNumber || offnum > PageGetMaxOffsetNumber(page))
 	{
-		LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-		ReleaseBuffer(buffer);
+		UnlockReleaseBuffer(buffer);
 		*userbuf = InvalidBuffer;
 		tuple->t_data = NULL;
 		return false;
@@ -1714,8 +1713,7 @@ heap_fetch(Relation relation,
 	 */
 	if (!ItemIdIsNormal(lp))
 	{
-		LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-		ReleaseBuffer(buffer);
+		UnlockReleaseBuffer(buffer);
 		*userbuf = InvalidBuffer;
 		tuple->t_data = NULL;
 		return false;
diff --git a/src/backend/access/heap/hio.c b/src/backend/access/heap/hio.c
index d26ceacd38c..1097f44a74e 100644
--- a/src/backend/access/heap/hio.c
+++ b/src/backend/access/heap/hio.c
@@ -711,14 +711,15 @@ loop:
 		 * unlock the two buffers in, so this can be slightly simpler than the
 		 * code above.
 		 */
-		LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
 		if (otherBuffer == InvalidBuffer)
-			ReleaseBuffer(buffer);
+			UnlockReleaseBuffer(buffer);
 		else if (otherBlock != targetBlock)
 		{
+			UnlockReleaseBuffer(buffer);
 			LockBuffer(otherBuffer, BUFFER_LOCK_UNLOCK);
-			ReleaseBuffer(buffer);
 		}
+		else
+			LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
 
 		/* Is there an ongoing bulk extension? */
 		if (bistate && bistate->next_free != InvalidBlockNumber)
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
index cc9c45dc40c..0547038616e 100644
--- a/src/backend/access/nbtree/nbtpage.c
+++ b/src/backend/access/nbtree/nbtpage.c
@@ -1011,24 +1011,47 @@ _bt_relandgetbuf(Relation rel, Buffer obuf, BlockNumber blkno, int access)
 
 	Assert(BlockNumberIsValid(blkno));
 	if (BufferIsValid(obuf))
-		_bt_unlockbuf(rel, obuf);
-	buf = ReleaseAndReadBuffer(obuf, rel, blkno);
-	_bt_lockbuf(rel, buf, access);
+	{
+		if (BufferGetBlockNumber(obuf) == blkno)
+		{
+			/* trade in old lock mode for new lock */
+			_bt_unlockbuf(rel, obuf);
+			buf = obuf;
+		}
+		else
+		{
+			/* release lock and pin at once, that's a bit more efficient */
+			_bt_relbuf(rel, obuf);
+			buf = ReadBuffer(rel, blkno);
+		}
+	}
+	else
+		buf = ReadBuffer(rel, blkno);
 
+	_bt_lockbuf(rel, buf, access);
 	_bt_checkpage(rel, buf);
+
 	return buf;
 }
 
 /*
  *	_bt_relbuf() -- release a locked buffer.
  *
- * Lock and pin (refcount) are both dropped.
+ * Lock and pin (refcount) are both dropped. This is a bit more efficient than
+ * doing the two operations separately.
  */
 void
 _bt_relbuf(Relation rel, Buffer buf)
 {
-	_bt_unlockbuf(rel, buf);
-	ReleaseBuffer(buf);
+	/*
+	 * Buffer is pinned and locked, which means that it is expected to be
+	 * defined and addressable.  Check that proactively.
+	 */
+	VALGRIND_CHECK_MEM_IS_DEFINED(BufferGetPage(buf), BLCKSZ);
+	if (!RelationUsesLocalBuffers(rel))
+		VALGRIND_MAKE_MEM_NOACCESS(BufferGetPage(buf), BLCKSZ);
+
+	UnlockReleaseBuffer(buf);
 }
 
 /*
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index f4f07c9a1c0..8a8c4adb9e1 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -2561,8 +2561,7 @@ again:
 			XLogNeedsFlush(BufferGetLSN(buf_hdr)) &&
 			StrategyRejectBuffer(strategy, buf_hdr, from_ring))
 		{
-			LockBuffer(buf, BUFFER_LOCK_UNLOCK);
-			UnpinBuffer(buf_hdr);
+			UnlockReleaseBuffer(buf);
 			goto again;
 		}
 
diff --git a/src/backend/storage/freespace/freespace.c b/src/backend/storage/freespace/freespace.c
index b9a8f368a63..40d67a96178 100644
--- a/src/backend/storage/freespace/freespace.c
+++ b/src/backend/storage/freespace/freespace.c
@@ -915,9 +915,8 @@ fsm_vacuum_page(Relation rel, FSMAddress addr,
 		((FSMPage) PageGetContents(page))->fp_next_slot = 0;
 		BufferFinishSetHintBits(buf, false, false);
 	}
-	LockBuffer(buf, BUFFER_LOCK_UNLOCK);
 
-	ReleaseBuffer(buf);
+	UnlockReleaseBuffer(buf);
 
 	return max_avail;
 }
diff --git a/src/test/modules/test_aio/test_aio.c b/src/test/modules/test_aio/test_aio.c
index 2ae4a559fab..138e1259dfd 100644
--- a/src/test/modules/test_aio/test_aio.c
+++ b/src/test/modules/test_aio/test_aio.c
@@ -221,9 +221,7 @@ modify_rel_block(PG_FUNCTION_ARGS)
 	 */
 	memcpy(page, BufferGetPage(buf), BLCKSZ);
 
-	LockBuffer(buf, BUFFER_LOCK_UNLOCK);
-
-	ReleaseBuffer(buf);
+	UnlockReleaseBuffer(buf);
 
 	/*
 	 * Don't want to have a buffer in-memory that's marked valid where the
@@ -496,8 +494,7 @@ invalidate_rel_block(PG_FUNCTION_ARGS)
 				else
 					FlushOneBuffer(buf);
 			}
-			LockBuffer(buf, BUFFER_LOCK_UNLOCK);
-			ReleaseBuffer(buf);
+			UnlockReleaseBuffer(buf);
 
 			if (BufferIsLocal(buf))
 				InvalidateLocalBuffer(GetLocalBufferDescriptor(-buf - 1), true);