diff --git a/src/backend/access/gin/ginfast.c b/src/backend/access/gin/ginfast.c
index 97b96848003..4ab815fefe0 100644
--- a/src/backend/access/gin/ginfast.c
+++ b/src/backend/access/gin/ginfast.c
@@ -39,7 +39,7 @@
 int			gin_pending_list_limit = 0;
 
 #define GIN_PAGE_FREESIZE \
-	( BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - MAXALIGN(sizeof(GinPageOpaqueData)) )
+	( (Size) BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - MAXALIGN(sizeof(GinPageOpaqueData)) )
 
 typedef struct KeyArray
 {
@@ -456,7 +456,7 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector)
 	 * ginInsertCleanup() should not be called inside our CRIT_SECTION.
 	 */
 	cleanupSize = GinGetPendingListCleanupSize(index);
-	if (metadata->nPendingPages * GIN_PAGE_FREESIZE > cleanupSize * 1024L)
+	if (metadata->nPendingPages * GIN_PAGE_FREESIZE > cleanupSize * (Size) 1024)
 		needCleanup = true;
 
 	UnlockReleaseBuffer(metabuffer);
@@ -795,7 +795,7 @@ ginInsertCleanup(GinState *ginstate, bool full_clean,
 				blknoFinish;
 	bool		cleanupFinish = false;
 	bool		fsm_vac = false;
-	Size		workMemory;
+	int			workMemory;
 
 	/*
 	 * We would like to prevent concurrent cleanup process. For that we will
@@ -901,7 +901,7 @@ ginInsertCleanup(GinState *ginstate, bool full_clean,
 		 */
 		if (GinPageGetOpaque(page)->rightlink == InvalidBlockNumber ||
 			(GinPageHasFullRow(page) &&
-			 (accum.allocatedMemory >= workMemory * 1024L)))
+			 accum.allocatedMemory >= workMemory * (Size) 1024))
 		{
 			ItemPointerData *list;
 			uint32		nlist;
diff --git a/src/backend/access/gin/ginget.c b/src/backend/access/gin/ginget.c
index 330805626ee..63dd1f3679f 100644
--- a/src/backend/access/gin/ginget.c
+++ b/src/backend/access/gin/ginget.c
@@ -125,7 +125,7 @@ collectMatchBitmap(GinBtreeData *btree, GinBtreeStack *stack,
 	CompactAttribute *attr;
 
 	/* Initialize empty bitmap result */
-	scanEntry->matchBitmap = tbm_create(work_mem * 1024L, NULL);
+	scanEntry->matchBitmap = tbm_create(work_mem * (Size) 1024, NULL);
 
 	/* Null query cannot partial-match anything */
 	if (scanEntry->isPartialMatch &&
diff --git a/src/backend/access/gin/gininsert.c b/src/backend/access/gin/gininsert.c
index 8e1788dbcf7..d1b5e8f0dd1 100644
--- a/src/backend/access/gin/gininsert.c
+++ b/src/backend/access/gin/gininsert.c
@@ -288,7 +288,7 @@ ginBuildCallback(Relation index, ItemPointer tid, Datum *values,
 							   values[i], isnull[i], tid);
 
 	/* If we've maxed out our available memory, dump everything to the index */
-	if (buildstate->accum.allocatedMemory >= (Size) maintenance_work_mem * 1024L)
+	if (buildstate->accum.allocatedMemory >= maintenance_work_mem * (Size) 1024)
 	{
 		ItemPointerData *list;
 		Datum		key;
diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c
index f950b9925f5..df8409ab233 100644
--- a/src/backend/access/hash/hash.c
+++ b/src/backend/access/hash/hash.c
@@ -120,7 +120,7 @@ hashbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 	double		reltuples;
 	double		allvisfrac;
 	uint32		num_buckets;
-	long		sort_threshold;
+	Size		sort_threshold;
 	HashBuildState buildstate;
 
 	/*
@@ -155,13 +155,13 @@ hashbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 	 * one page.  Also, "initial index size" accounting does not include the
 	 * metapage, nor the first bitmap page.
 	 */
-	sort_threshold = (maintenance_work_mem * 1024L) / BLCKSZ;
+	sort_threshold = (maintenance_work_mem * (Size) 1024) / BLCKSZ;
 	if (index->rd_rel->relpersistence != RELPERSISTENCE_TEMP)
 		sort_threshold = Min(sort_threshold, NBuffers);
 	else
 		sort_threshold = Min(sort_threshold, NLocBuffer);
 
-	if (num_buckets >= (uint32) sort_threshold)
+	if (num_buckets >= sort_threshold)
 		buildstate.spool = _h_spoolinit(heap, index, num_buckets);
 	else
 		buildstate.spool = NULL;
diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 5ed43e43914..075af385cd1 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -2070,7 +2070,7 @@ lazy_vacuum(LVRelState *vacrel)
 		 */
 		threshold = (double) vacrel->rel_pages * BYPASS_THRESHOLD_PAGES;
 		bypass = (vacrel->lpdead_item_pages < threshold &&
-				  (TidStoreMemoryUsage(vacrel->dead_items) < (32L * 1024L * 1024L)));
+				  TidStoreMemoryUsage(vacrel->dead_items) < 32 * 1024 * 1024);
 	}
 
 	if (bypass)
@@ -3037,7 +3037,7 @@ dead_items_alloc(LVRelState *vacrel, int nworkers)
 	 */
 
 	dead_items_info = (VacDeadItemsInfo *) palloc(sizeof(VacDeadItemsInfo));
-	dead_items_info->max_bytes = vac_work_mem * 1024L;
+	dead_items_info->max_bytes = vac_work_mem * (Size) 1024;
 	dead_items_info->num_items = 0;
 	vacrel->dead_items_info = dead_items_info;
 
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
index 111675d2ef8..5321e256b1a 100644
--- a/src/backend/access/nbtree/nbtpage.c
+++ b/src/backend/access/nbtree/nbtpage.c
@@ -2953,7 +2953,7 @@ _bt_lock_subtree_parent(Relation rel, Relation heaprel, BlockNumber child,
 void
 _bt_pendingfsm_init(Relation rel, BTVacState *vstate, bool cleanuponly)
 {
-	int64		maxbufsize;
+	Size		maxbufsize;
 
 	/*
 	 * Don't bother with optimization in cleanup-only case -- we don't expect
@@ -2969,12 +2969,13 @@ _bt_pendingfsm_init(Relation rel, BTVacState *vstate, bool cleanuponly)
 	 * int overflow here.
 	 */
 	vstate->bufsize = 256;
-	maxbufsize = (work_mem * 1024L) / sizeof(BTPendingFSM);
-	maxbufsize = Min(maxbufsize, INT_MAX);
+	maxbufsize = (work_mem * (Size) 1024) / sizeof(BTPendingFSM);
 	maxbufsize = Min(maxbufsize, MaxAllocSize / sizeof(BTPendingFSM));
+	/* BTVacState.maxbufsize has type int */
+	maxbufsize = Min(maxbufsize, INT_MAX);
 	/* Stay sane with small work_mem */
 	maxbufsize = Max(maxbufsize, vstate->bufsize);
-	vstate->maxbufsize = maxbufsize;
+	vstate->maxbufsize = (int) maxbufsize;
 
 	/* Allocate buffer, indicate that there are currently 0 pending pages */
 	vstate->pendingpages = palloc(sizeof(BTPendingFSM) * vstate->bufsize);
diff --git a/src/backend/commands/vacuumparallel.c b/src/backend/commands/vacuumparallel.c
index 0d92e694d6a..49e605a6ffc 100644
--- a/src/backend/commands/vacuumparallel.c
+++ b/src/backend/commands/vacuumparallel.c
@@ -375,7 +375,7 @@ parallel_vacuum_init(Relation rel, Relation *indrels, int nindexes,
 		(nindexes_mwm > 0) ?
 		maintenance_work_mem / Min(parallel_workers, nindexes_mwm) :
 		maintenance_work_mem;
-	shared->dead_items_info.max_bytes = vac_work_mem * 1024L;
+	shared->dead_items_info.max_bytes = vac_work_mem * (size_t) 1024;
 
 	/* Prepare DSA space for dead items */
 	dead_items = TidStoreCreateShared(shared->dead_items_info.max_bytes,
diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index 6aac6f3a872..00564985668 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -326,7 +326,7 @@ CreateWorkExprContext(EState *estate)
 	Size		maxBlockSize = ALLOCSET_DEFAULT_MAXSIZE;
 
 	/* choose the maxBlockSize to be no larger than 1/16 of work_mem */
-	while (16 * maxBlockSize > work_mem * 1024L)
+	while (maxBlockSize > work_mem * (Size) 1024 / 16)
 		maxBlockSize >>= 1;
 
 	if (maxBlockSize < ALLOCSET_DEFAULT_INITSIZE)
diff --git a/src/backend/executor/nodeBitmapIndexscan.c b/src/backend/executor/nodeBitmapIndexscan.c
index d3ef5a00040..0b32c3a022f 100644
--- a/src/backend/executor/nodeBitmapIndexscan.c
+++ b/src/backend/executor/nodeBitmapIndexscan.c
@@ -91,7 +91,7 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
 	else
 	{
 		/* XXX should we use less than work_mem for this? */
-		tbm = tbm_create(work_mem * 1024L,
+		tbm = tbm_create(work_mem * (Size) 1024,
 						 ((BitmapIndexScan *) node->ss.ps.plan)->isshared ?
 						 node->ss.ps.state->es_query_dsa : NULL);
 	}
diff --git a/src/backend/executor/nodeBitmapOr.c b/src/backend/executor/nodeBitmapOr.c
index a9ede1c1087..231760ec93d 100644
--- a/src/backend/executor/nodeBitmapOr.c
+++ b/src/backend/executor/nodeBitmapOr.c
@@ -143,7 +143,7 @@ MultiExecBitmapOr(BitmapOrState *node)
 			if (result == NULL) /* first subplan */
 			{
 				/* XXX should we use less than work_mem for this? */
-				result = tbm_create(work_mem * 1024L,
+				result = tbm_create(work_mem * (Size) 1024,
 									((BitmapOr *) node->ps.plan)->isshared ?
 									node->ps.state->es_query_dsa : NULL);
 			}
diff --git a/src/backend/nodes/tidbitmap.c b/src/backend/nodes/tidbitmap.c
index af6ac64b3fc..66b3c387d53 100644
--- a/src/backend/nodes/tidbitmap.c
+++ b/src/backend/nodes/tidbitmap.c
@@ -263,7 +263,7 @@ static int	tbm_shared_comparator(const void *left, const void *right,
  * be allocated from the DSA.
  */
 TIDBitmap *
-tbm_create(long maxbytes, dsa_area *dsa)
+tbm_create(Size maxbytes, dsa_area *dsa)
 {
 	TIDBitmap  *tbm;
 
@@ -273,7 +273,7 @@ tbm_create(long maxbytes, dsa_area *dsa)
 	tbm->mcxt = CurrentMemoryContext;
 	tbm->status = TBM_EMPTY;
 
-	tbm->maxentries = (int) tbm_calculate_entries(maxbytes);
+	tbm->maxentries = tbm_calculate_entries(maxbytes);
 	tbm->lossify_start = 0;
 	tbm->dsa = dsa;
 	tbm->dsapagetable = InvalidDsaPointer;
@@ -1539,10 +1539,10 @@ pagetable_free(pagetable_hash *pagetable, void *pointer)
  *
  * Estimate number of hashtable entries we can have within maxbytes.
  */
-long
-tbm_calculate_entries(double maxbytes)
+int
+tbm_calculate_entries(Size maxbytes)
 {
-	long		nbuckets;
+	Size		nbuckets;
 
 	/*
 	 * Estimate number of hashtable entries we can have within maxbytes. This
@@ -1555,7 +1555,7 @@ tbm_calculate_entries(double maxbytes)
 	nbuckets = Min(nbuckets, INT_MAX - 1);	/* safety limit */
 	nbuckets = Max(nbuckets, 16);	/* sanity limit */
 
-	return nbuckets;
+	return (int) nbuckets;
 }
 
 /*
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index ec004ed9493..73d78617009 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -1903,7 +1903,7 @@ cost_tuplesort(Cost *startup_cost, Cost *run_cost,
 	double		input_bytes = relation_byte_size(tuples, width);
 	double		output_bytes;
 	double		output_tuples;
-	long		sort_mem_bytes = sort_mem * 1024L;
+	int64		sort_mem_bytes = sort_mem * (int64) 1024;
 
 	/*
 	 * We want to be sure the cost of a sort is never estimated as zero, even
@@ -2488,7 +2488,7 @@ cost_material(Path *path,
 	Cost		startup_cost = input_startup_cost;
 	Cost		run_cost = input_total_cost - input_startup_cost;
 	double		nbytes = relation_byte_size(tuples, width);
-	long		work_mem_bytes = work_mem * 1024L;
+	double		work_mem_bytes = work_mem * (Size) 1024;
 
 	path->rows = tuples;
 
@@ -4028,7 +4028,7 @@ final_cost_mergejoin(PlannerInfo *root, MergePath *path,
 	else if (enable_material && innersortkeys != NIL &&
 			 relation_byte_size(inner_path_rows,
 								inner_path->pathtarget->width) >
-			 (work_mem * 1024L))
+			 work_mem * (Size) 1024)
 		path->materialize_inner = true;
 	else
 		path->materialize_inner = false;
@@ -4663,7 +4663,7 @@ cost_rescan(PlannerInfo *root, Path *path,
 				Cost		run_cost = cpu_tuple_cost * path->rows;
 				double		nbytes = relation_byte_size(path->rows,
 														path->pathtarget->width);
-				long		work_mem_bytes = work_mem * 1024L;
+				double		work_mem_bytes = work_mem * (Size) 1024;
 
 				if (nbytes > work_mem_bytes)
 				{
@@ -4690,7 +4690,7 @@ cost_rescan(PlannerInfo *root, Path *path,
 				Cost		run_cost = cpu_operator_cost * path->rows;
 				double		nbytes = relation_byte_size(path->rows,
 														path->pathtarget->width);
-				long		work_mem_bytes = work_mem * 1024L;
+				double		work_mem_bytes = work_mem * (Size) 1024;
 
 				if (nbytes > work_mem_bytes)
 				{
@@ -6496,7 +6496,7 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 	double		pages_fetched;
 	double		tuples_fetched;
 	double		heap_pages;
-	long		maxentries;
+	double		maxentries;
 
 	/*
 	 * Fetch total cost of obtaining the bitmap, as well as its total
@@ -6527,7 +6527,7 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 	 * the bitmap at one time.)
 	 */
 	heap_pages = Min(pages_fetched, baserel->pages);
-	maxentries = tbm_calculate_entries(work_mem * 1024L);
+	maxentries = tbm_calculate_entries(work_mem * (Size) 1024);
 
 	if (loop_count > 1)
 	{
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 8a474a50be7..ffd7517ea97 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -6887,7 +6887,7 @@ plan_create_index_workers(Oid tableOid, Oid indexOid)
 	 * parallel worker to sort.
 	 */
 	while (parallel_workers > 0 &&
-		   maintenance_work_mem / (parallel_workers + 1) < 32768L)
+		   maintenance_work_mem / (parallel_workers + 1) < 32 * 1024)
 		parallel_workers--;
 
 done:
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 5389eec20d2..10a37667a51 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -3643,7 +3643,7 @@ ReorderBufferCheckMemoryLimit(ReorderBuffer *rb)
 	 * haven't exceeded the memory limit.
 	 */
 	if (debug_logical_replication_streaming == DEBUG_LOGICAL_REP_STREAMING_BUFFERED &&
-		rb->size < logical_decoding_work_mem * 1024L)
+		rb->size < logical_decoding_work_mem * (Size) 1024)
 		return;
 
 	/*
@@ -3656,7 +3656,7 @@ ReorderBufferCheckMemoryLimit(ReorderBuffer *rb)
 	 * because a user can reduce the logical_decoding_work_mem to a smaller
 	 * value before the most recent change.
 	 */
-	while (rb->size >= logical_decoding_work_mem * 1024L ||
+	while (rb->size >= logical_decoding_work_mem * (Size) 1024 ||
 		   (debug_logical_replication_streaming == DEBUG_LOGICAL_REP_STREAMING_IMMEDIATE &&
 			rb->size > 0))
 	{
@@ -3699,8 +3699,7 @@ ReorderBufferCheckMemoryLimit(ReorderBuffer *rb)
 	}
 
 	/* We must be under the memory limit now. */
-	Assert(rb->size < logical_decoding_work_mem * 1024L);
-
+	Assert(rb->size < logical_decoding_work_mem * (Size) 1024);
 }
 
 /*
diff --git a/src/backend/utils/sort/tuplestore.c b/src/backend/utils/sort/tuplestore.c
index aacec8b7993..d61b601053c 100644
--- a/src/backend/utils/sort/tuplestore.c
+++ b/src/backend/utils/sort/tuplestore.c
@@ -265,7 +265,7 @@ tuplestore_begin_common(int eflags, bool interXact, int maxKBytes)
 	state->truncated = false;
 	state->usedDisk = false;
 	state->maxSpace = 0;
-	state->allowedMem = maxKBytes * 1024L;
+	state->allowedMem = maxKBytes * (int64) 1024;
 	state->availMem = state->allowedMem;
 	state->myfile = NULL;
 
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index 67ae89c8257..ecff4842fd3 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -147,7 +147,7 @@ typedef struct HashMemoryChunkData
 
 typedef struct HashMemoryChunkData *HashMemoryChunk;
 
-#define HASH_CHUNK_SIZE			(32 * 1024L)
+#define HASH_CHUNK_SIZE			((Size) (32 * 1024))
 #define HASH_CHUNK_HEADER_SIZE	MAXALIGN(sizeof(HashMemoryChunkData))
 #define HASH_CHUNK_DATA(hc)		(((char *) (hc)) + HASH_CHUNK_HEADER_SIZE)
 /* tuples exceeding HASH_CHUNK_THRESHOLD bytes are put in their own chunk */
diff --git a/src/include/nodes/tidbitmap.h b/src/include/nodes/tidbitmap.h
index fedbf69eb53..a6ffeac90be 100644
--- a/src/include/nodes/tidbitmap.h
+++ b/src/include/nodes/tidbitmap.h
@@ -62,7 +62,7 @@ typedef struct TBMIterateResult
 
 /* function prototypes in nodes/tidbitmap.c */
 
-extern TIDBitmap *tbm_create(long maxbytes, dsa_area *dsa);
+extern TIDBitmap *tbm_create(Size maxbytes, dsa_area *dsa);
 extern void tbm_free(TIDBitmap *tbm);
 extern void tbm_free_shared_area(dsa_area *dsa, dsa_pointer dp);
 
@@ -84,7 +84,7 @@ extern void tbm_end_private_iterate(TBMPrivateIterator *iterator);
 extern void tbm_end_shared_iterate(TBMSharedIterator *iterator);
 extern TBMSharedIterator *tbm_attach_shared_iterate(dsa_area *dsa,
 													dsa_pointer dp);
-extern long tbm_calculate_entries(double maxbytes);
+extern int	tbm_calculate_entries(Size maxbytes);
 
 extern TBMIterator tbm_begin_iterate(TIDBitmap *tbm,
 									 dsa_area *dsa, dsa_pointer dsp);
diff --git a/src/include/utils/dsa.h b/src/include/utils/dsa.h
index 44f546f5940..9eca8788908 100644
--- a/src/include/utils/dsa.h
+++ b/src/include/utils/dsa.h
@@ -97,7 +97,7 @@ typedef pg_atomic_uint64 dsa_pointer_atomic;
 #define DSA_DEFAULT_INIT_SEGMENT_SIZE ((size_t) (1 * 1024 * 1024))
 
 /* The minimum size of a DSM segment. */
-#define DSA_MIN_SEGMENT_SIZE	((size_t) (256 * 1024L))
+#define DSA_MIN_SEGMENT_SIZE	((size_t) (256 * 1024))
 
 /* The maximum size of a DSM segment. */
 #define DSA_MAX_SEGMENT_SIZE ((size_t) 1 << DSA_OFFSET_WIDTH)
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 532d6642bb4..1233e07d7da 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -17,9 +17,13 @@
 #include "utils/array.h"
 
 
-/* upper limit for GUC variables measured in kilobytes of memory */
-/* note that various places assume the byte size fits in a "long" variable */
-#if SIZEOF_SIZE_T > 4 && SIZEOF_LONG > 4
+/*
+ * Maximum for integer GUC variables that are measured in kilobytes of memory.
+ * This value is chosen to ensure that the corresponding number of bytes fits
+ * into a variable of type size_t or ssize_t.  Be sure to compute the number
+ * of bytes like "guc_var * (Size) 1024" to avoid int-width overflow.
+ */
+#if SIZEOF_SIZE_T > 4
 #define MAX_KILOBYTES	INT_MAX
 #else
 #define MAX_KILOBYTES	(INT_MAX / 1024)
diff --git a/src/test/modules/test_bloomfilter/test_bloomfilter.c b/src/test/modules/test_bloomfilter/test_bloomfilter.c
index ed36684276b..499d437a9c4 100644
--- a/src/test/modules/test_bloomfilter/test_bloomfilter.c
+++ b/src/test/modules/test_bloomfilter/test_bloomfilter.c
@@ -76,7 +76,7 @@ create_and_test_bloom(int power, int64 nelements, int callerseed)
 	int64		nfalsepos;
 	bloom_filter *filter;
 
-	bloom_work_mem = (1L << power) / 8L / 1024L;
+	bloom_work_mem = ((int64) 1 << power) / (8 * 1024);
 
 	elog(DEBUG1, "bloom_work_mem (KB): %d", bloom_work_mem);