[HACKERS] wrong t_bits alignment in pageinspect

diff --git a/contrib/pageinspect/expected/page.out b/contrib/pageinspect/expected/page.out
index 8e15947a81..97af6f5bd2 100644
--- a/contrib/pageinspect/expected/page.out
+++ b/contrib/pageinspect/expected/page.out
@@ -92,3 +92,20 @@ create table test_part1 partition of test_partitioned for values from ( 1 ) to (
 select get_raw_page('test_part1', 0); -- get farther and error about empty table
 ERROR:  block number 0 is out of range for relation "test_part1"
 drop table test_partitioned;
+-- check null bitmap alignment for table whose the number of attributes is multiple of 8
+create table test8 (f1 int, f2 int, f3 int, f4 int, f5 int, f6 int, f7 int, f8 int);
+insert into test8(f1, f8) values (x'f1'::int, 0);
+select t_bits, t_data from heap_page_items(get_raw_page('test8', 0));
+  t_bits  |       t_data       
+----------+--------------------
+ 10000001 | \xf100000000000000
+(1 row)
+
+select tuple_data_split('test8'::regclass, t_data, t_infomask, t_infomask2, t_bits)
+    from heap_page_items(get_raw_page('test8', 0));
+                      tuple_data_split                       
+-------------------------------------------------------------
+ {"\\xf1000000",NULL,NULL,NULL,NULL,NULL,NULL,"\\x00000000"}
+(1 row)
+
+drop table test8;
diff --git a/contrib/pageinspect/heapfuncs.c b/contrib/pageinspect/heapfuncs.c
index 088254453e..99f409846c 100644
--- a/contrib/pageinspect/heapfuncs.c
+++ b/contrib/pageinspect/heapfuncs.c
@@ -234,7 +234,7 @@ heap_page_items(PG_FUNCTION_ARGS)
 					int			bits_len;
 
 					bits_len =
-						((tuphdr->t_infomask2 & HEAP_NATTS_MASK) / 8 + 1) * 8;
+						BITMAPLEN(HeapTupleHeaderGetNatts(tuphdr)) * BITS_PER_BYTE;
 					values[11] = CStringGetTextDatum(
 													 bits_to_text(tuphdr->t_bits, bits_len));
 				}
@@ -436,12 +436,12 @@ tuple_data_split(PG_FUNCTION_ARGS)
 		int			bits_str_len;
 		int			bits_len;
 
-		bits_len = (t_infomask2 & HEAP_NATTS_MASK) / 8 + 1;
+		bits_len = BITMAPLEN(t_infomask2 & HEAP_NATTS_MASK) * BITS_PER_BYTE;
 		if (!t_bits_str)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg("argument of t_bits is null, but it is expected to be null and %d character long",
-							bits_len * 8)));
+							bits_len)));
 
 		bits_str_len = strlen(t_bits_str);
 		if ((bits_str_len % 8) != 0)
@@ -449,11 +449,11 @@ tuple_data_split(PG_FUNCTION_ARGS)
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg("length of t_bits is not a multiple of eight")));
 
-		if (bits_len * 8 != bits_str_len)
+		if (bits_len != bits_str_len)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg("unexpected length of t_bits %u, expected %d",
-							bits_str_len, bits_len * 8)));
+							bits_str_len, bits_len)));
 
 		/* do the conversion */
 		t_bits = text_to_bits(t_bits_str, bits_str_len);
diff --git a/contrib/pageinspect/sql/page.sql b/contrib/pageinspect/sql/page.sql
index 493ca9b211..16b4571fbf 100644
--- a/contrib/pageinspect/sql/page.sql
+++ b/contrib/pageinspect/sql/page.sql
@@ -41,3 +41,11 @@ select get_raw_page('test_partitioned', 0); -- error about partitioned table
 create table test_part1 partition of test_partitioned for values from ( 1 ) to (100);
 select get_raw_page('test_part1', 0); -- get farther and error about empty table
 drop table test_partitioned;
+
+-- check null bitmap alignment for table whose the number of attributes is multiple of 8
+create table test8 (f1 int, f2 int, f3 int, f4 int, f5 int, f6 int, f7 int, f8 int);
+insert into test8(f1, f8) values (x'f1'::int, 0);
+select t_bits, t_data from heap_page_items(get_raw_page('test8', 0));
+select tuple_data_split('test8'::regclass, t_data, t_infomask, t_infomask2, t_bits)
+    from heap_page_items(get_raw_page('test8', 0));
+drop table test8;