diff --git a/contrib/pg_buffercache/pg_buffercache_pages.c b/contrib/pg_buffercache/pg_buffercache_pages.c
index b682dca658b..dcba3fb5473 100644
--- a/contrib/pg_buffercache/pg_buffercache_pages.c
+++ b/contrib/pg_buffercache/pg_buffercache_pages.c
@@ -199,7 +199,7 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
 		for (i = 0; i < NBuffers; i++)
 		{
 			BufferDesc *bufHdr;
-			uint32		buf_state;
+			uint64		buf_state;
 
 			CHECK_FOR_INTERRUPTS();
 
@@ -615,7 +615,7 @@ pg_buffercache_summary(PG_FUNCTION_ARGS)
 	for (int i = 0; i < NBuffers; i++)
 	{
 		BufferDesc *bufHdr;
-		uint32		buf_state;
+		uint64		buf_state;
 
 		CHECK_FOR_INTERRUPTS();
 
@@ -626,7 +626,7 @@ pg_buffercache_summary(PG_FUNCTION_ARGS)
 		 * noticeably increase the cost of the function.
 		 */
 		bufHdr = GetBufferDescriptor(i);
-		buf_state = pg_atomic_read_u32(&bufHdr->state);
+		buf_state = pg_atomic_read_u64(&bufHdr->state);
 
 		if (buf_state & BM_VALID)
 		{
@@ -676,7 +676,7 @@ pg_buffercache_usage_counts(PG_FUNCTION_ARGS)
 	for (int i = 0; i < NBuffers; i++)
 	{
 		BufferDesc *bufHdr = GetBufferDescriptor(i);
-		uint32		buf_state = pg_atomic_read_u32(&bufHdr->state);
+		uint64		buf_state = pg_atomic_read_u64(&bufHdr->state);
 		int			usage_count;
 
 		CHECK_FOR_INTERRUPTS();
diff --git a/contrib/pg_prewarm/autoprewarm.c b/contrib/pg_prewarm/autoprewarm.c
index 3ca7d2ed772..89e187425cc 100644
--- a/contrib/pg_prewarm/autoprewarm.c
+++ b/contrib/pg_prewarm/autoprewarm.c
@@ -703,7 +703,7 @@ apw_dump_now(bool is_bgworker, bool dump_unlogged)
 
 	for (num_blocks = 0, i = 0; i < NBuffers; i++)
 	{
-		uint32		buf_state;
+		uint64		buf_state;
 
 		CHECK_FOR_INTERRUPTS();
 
diff --git a/src/backend/storage/buffer/buf_init.c b/src/backend/storage/buffer/buf_init.c
index 9a312bcc7b3..7d894522526 100644
--- a/src/backend/storage/buffer/buf_init.c
+++ b/src/backend/storage/buffer/buf_init.c
@@ -121,7 +121,7 @@ BufferManagerShmemInit(void)
 
 			ClearBufferTag(&buf->tag);
 
-			pg_atomic_init_u32(&buf->state, 0);
+			pg_atomic_init_u64(&buf->state, 0);
 			buf->wait_backend_pgprocno = INVALID_PROC_NUMBER;
 
 			buf->buf_id = i;
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index a036c2aa275..b0de8e45d4d 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -780,7 +780,7 @@ ReadRecentBuffer(RelFileLocator rlocator, ForkNumber forkNum, BlockNumber blockN
 {
 	BufferDesc *bufHdr;
 	BufferTag	tag;
-	uint32		buf_state;
+	uint64		buf_state;
 
 	Assert(BufferIsValid(recent_buffer));
 
@@ -793,7 +793,7 @@ ReadRecentBuffer(RelFileLocator rlocator, ForkNumber forkNum, BlockNumber blockN
 		int			b = -recent_buffer - 1;
 
 		bufHdr = GetLocalBufferDescriptor(b);
-		buf_state = pg_atomic_read_u32(&bufHdr->state);
+		buf_state = pg_atomic_read_u64(&bufHdr->state);
 
 		/* Is it still valid and holding the right tag? */
 		if ((buf_state & BM_VALID) && BufferTagsEqual(&tag, &bufHdr->tag))
@@ -1386,8 +1386,8 @@ StartReadBuffersImpl(ReadBuffersOperation *operation,
 				bufHdr = GetLocalBufferDescriptor(-buffers[i] - 1);
 			else
 				bufHdr = GetBufferDescriptor(buffers[i] - 1);
-			Assert(pg_atomic_read_u32(&bufHdr->state) & BM_TAG_VALID);
-			found = pg_atomic_read_u32(&bufHdr->state) & BM_VALID;
+			Assert(pg_atomic_read_u64(&bufHdr->state) & BM_TAG_VALID);
+			found = pg_atomic_read_u64(&bufHdr->state) & BM_VALID;
 		}
 		else
 		{
@@ -1613,10 +1613,10 @@ CheckReadBuffersOperation(ReadBuffersOperation *operation, bool is_complete)
 			GetBufferDescriptor(buffer - 1);
 
 		Assert(BufferGetBlockNumber(buffer) == operation->blocknum + i);
-		Assert(pg_atomic_read_u32(&buf_hdr->state) & BM_TAG_VALID);
+		Assert(pg_atomic_read_u64(&buf_hdr->state) & BM_TAG_VALID);
 
 		if (i < operation->nblocks_done)
-			Assert(pg_atomic_read_u32(&buf_hdr->state) & BM_VALID);
+			Assert(pg_atomic_read_u64(&buf_hdr->state) & BM_VALID);
 	}
 #endif
 }
@@ -2083,8 +2083,8 @@ BufferAlloc(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
 	int			existing_buf_id;
 	Buffer		victim_buffer;
 	BufferDesc *victim_buf_hdr;
-	uint32		victim_buf_state;
-	uint32		set_bits = 0;
+	uint64		victim_buf_state;
+	uint64		set_bits = 0;
 
 	/* Make sure we will have room to remember the buffer pin */
 	ResourceOwnerEnlarge(CurrentResourceOwner);
@@ -2251,7 +2251,7 @@ InvalidateBuffer(BufferDesc *buf)
 	uint32		oldHash;		/* hash value for oldTag */
 	LWLock	   *oldPartitionLock;	/* buffer partition lock for it */
 	uint32		oldFlags;
-	uint32		buf_state;
+	uint64		buf_state;
 
 	/* Save the original buffer tag before dropping the spinlock */
 	oldTag = buf->tag;
@@ -2342,7 +2342,7 @@ retry:
 static bool
 InvalidateVictimBuffer(BufferDesc *buf_hdr)
 {
-	uint32		buf_state;
+	uint64		buf_state;
 	uint32		hash;
 	LWLock	   *partition_lock;
 	BufferTag	tag;
@@ -2402,10 +2402,10 @@ InvalidateVictimBuffer(BufferDesc *buf_hdr)
 
 	LWLockRelease(partition_lock);
 
-	buf_state = pg_atomic_read_u32(&buf_hdr->state);
+	buf_state = pg_atomic_read_u64(&buf_hdr->state);
 	Assert(!(buf_state & (BM_DIRTY | BM_VALID | BM_TAG_VALID)));
 	Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
-	Assert(BUF_STATE_GET_REFCOUNT(pg_atomic_read_u32(&buf_hdr->state)) > 0);
+	Assert(BUF_STATE_GET_REFCOUNT(pg_atomic_read_u64(&buf_hdr->state)) > 0);
 
 	return true;
 }
@@ -2415,7 +2415,7 @@ GetVictimBuffer(BufferAccessStrategy strategy, IOContext io_context)
 {
 	BufferDesc *buf_hdr;
 	Buffer		buf;
-	uint32		buf_state;
+	uint64		buf_state;
 	bool		from_ring;
 
 	/*
@@ -2548,7 +2548,7 @@ again:
 
 	/* a final set of sanity checks */
 #ifdef USE_ASSERT_CHECKING
-	buf_state = pg_atomic_read_u32(&buf_hdr->state);
+	buf_state = pg_atomic_read_u64(&buf_hdr->state);
 
 	Assert(BUF_STATE_GET_REFCOUNT(buf_state) == 1);
 	Assert(!(buf_state & (BM_TAG_VALID | BM_VALID | BM_DIRTY)));
@@ -2839,13 +2839,13 @@ ExtendBufferedRelShared(BufferManagerRelation bmr,
 			 */
 			do
 			{
-				pg_atomic_fetch_and_u32(&existing_hdr->state, ~BM_VALID);
+				pg_atomic_fetch_and_u64(&existing_hdr->state, ~BM_VALID);
 			} while (!StartBufferIO(existing_hdr, true, false));
 		}
 		else
 		{
-			uint32		buf_state;
-			uint32		set_bits = 0;
+			uint64		buf_state;
+			uint64		set_bits = 0;
 
 			buf_state = LockBufHdr(victim_buf_hdr);
 
@@ -3021,7 +3021,7 @@ BufferIsDirty(Buffer buffer)
 		Assert(BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_EXCLUSIVE));
 	}
 
-	return pg_atomic_read_u32(&bufHdr->state) & BM_DIRTY;
+	return pg_atomic_read_u64(&bufHdr->state) & BM_DIRTY;
 }
 
 /*
@@ -3037,8 +3037,8 @@ void
 MarkBufferDirty(Buffer buffer)
 {
 	BufferDesc *bufHdr;
-	uint32		buf_state;
-	uint32		old_buf_state;
+	uint64		buf_state;
+	uint64		old_buf_state;
 
 	if (!BufferIsValid(buffer))
 		elog(ERROR, "bad buffer ID: %d", buffer);
@@ -3058,7 +3058,7 @@ MarkBufferDirty(Buffer buffer)
 	 * NB: We have to wait for the buffer header spinlock to be not held, as
 	 * TerminateBufferIO() relies on the spinlock.
 	 */
-	old_buf_state = pg_atomic_read_u32(&bufHdr->state);
+	old_buf_state = pg_atomic_read_u64(&bufHdr->state);
 	for (;;)
 	{
 		if (old_buf_state & BM_LOCKED)
@@ -3069,7 +3069,7 @@ MarkBufferDirty(Buffer buffer)
 		Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
 		buf_state |= BM_DIRTY | BM_JUST_DIRTIED;
 
-		if (pg_atomic_compare_exchange_u32(&bufHdr->state, &old_buf_state,
+		if (pg_atomic_compare_exchange_u64(&bufHdr->state, &old_buf_state,
 										   buf_state))
 			break;
 	}
@@ -3173,10 +3173,10 @@ PinBuffer(BufferDesc *buf, BufferAccessStrategy strategy,
 
 	if (ref == NULL)
 	{
-		uint32		buf_state;
-		uint32		old_buf_state;
+		uint64		buf_state;
+		uint64		old_buf_state;
 
-		old_buf_state = pg_atomic_read_u32(&buf->state);
+		old_buf_state = pg_atomic_read_u64(&buf->state);
 		for (;;)
 		{
 			if (unlikely(skip_if_not_valid && !(old_buf_state & BM_VALID)))
@@ -3210,7 +3210,7 @@ PinBuffer(BufferDesc *buf, BufferAccessStrategy strategy,
 					buf_state += BUF_USAGECOUNT_ONE;
 			}
 
-			if (pg_atomic_compare_exchange_u32(&buf->state, &old_buf_state,
+			if (pg_atomic_compare_exchange_u64(&buf->state, &old_buf_state,
 											   buf_state))
 			{
 				result = (buf_state & BM_VALID) != 0;
@@ -3237,7 +3237,7 @@ PinBuffer(BufferDesc *buf, BufferAccessStrategy strategy,
 		 * that the buffer page is legitimately non-accessible here.  We
 		 * cannot meddle with that.
 		 */
-		result = (pg_atomic_read_u32(&buf->state) & BM_VALID) != 0;
+		result = (pg_atomic_read_u64(&buf->state) & BM_VALID) != 0;
 
 		Assert(ref->data.refcount > 0);
 		ref->data.refcount++;
@@ -3272,7 +3272,7 @@ PinBuffer(BufferDesc *buf, BufferAccessStrategy strategy,
 static void
 PinBuffer_Locked(BufferDesc *buf)
 {
-	uint32		old_buf_state;
+	uint64		old_buf_state;
 
 	/*
 	 * As explained, We don't expect any preexisting pins. That allows us to
@@ -3284,7 +3284,7 @@ PinBuffer_Locked(BufferDesc *buf)
 	 * Since we hold the buffer spinlock, we can update the buffer state and
 	 * release the lock in one operation.
 	 */
-	old_buf_state = pg_atomic_read_u32(&buf->state);
+	old_buf_state = pg_atomic_read_u64(&buf->state);
 
 	UnlockBufHdrExt(buf, old_buf_state,
 					0, 0, 1);
@@ -3314,7 +3314,7 @@ WakePinCountWaiter(BufferDesc *buf)
 	 * BM_PIN_COUNT_WAITER if it stops waiting for a reason other than this
 	 * backend waking it up.
 	 */
-	uint32		buf_state = LockBufHdr(buf);
+	uint64		buf_state = LockBufHdr(buf);
 
 	if ((buf_state & BM_PIN_COUNT_WAITER) &&
 		BUF_STATE_GET_REFCOUNT(buf_state) == 1)
@@ -3361,7 +3361,7 @@ UnpinBufferNoOwner(BufferDesc *buf)
 	ref->data.refcount--;
 	if (ref->data.refcount == 0)
 	{
-		uint32		old_buf_state;
+		uint64		old_buf_state;
 
 		/*
 		 * Mark buffer non-accessible to Valgrind.
@@ -3379,7 +3379,7 @@ UnpinBufferNoOwner(BufferDesc *buf)
 		Assert(!LWLockHeldByMe(BufferDescriptorGetContentLock(buf)));
 
 		/* decrement the shared reference count */
-		old_buf_state = pg_atomic_fetch_sub_u32(&buf->state, BUF_REFCOUNT_ONE);
+		old_buf_state = pg_atomic_fetch_sub_u64(&buf->state, BUF_REFCOUNT_ONE);
 
 		/* Support LockBufferForCleanup() */
 		if (old_buf_state & BM_PIN_COUNT_WAITER)
@@ -3436,7 +3436,7 @@ TrackNewBufferPin(Buffer buf)
 static void
 BufferSync(int flags)
 {
-	uint32		buf_state;
+	uint64		buf_state;
 	int			buf_id;
 	int			num_to_scan;
 	int			num_spaces;
@@ -3446,7 +3446,7 @@ BufferSync(int flags)
 	Oid			last_tsid;
 	binaryheap *ts_heap;
 	int			i;
-	uint32		mask = BM_DIRTY;
+	uint64		mask = BM_DIRTY;
 	WritebackContext wb_context;
 
 	/*
@@ -3478,7 +3478,7 @@ BufferSync(int flags)
 	for (buf_id = 0; buf_id < NBuffers; buf_id++)
 	{
 		BufferDesc *bufHdr = GetBufferDescriptor(buf_id);
-		uint32		set_bits = 0;
+		uint64		set_bits = 0;
 
 		/*
 		 * Header spinlock is enough to examine BM_DIRTY, see comment in
@@ -3645,7 +3645,7 @@ BufferSync(int flags)
 		 * write the buffer though we didn't need to.  It doesn't seem worth
 		 * guarding against this, though.
 		 */
-		if (pg_atomic_read_u32(&bufHdr->state) & BM_CHECKPOINT_NEEDED)
+		if (pg_atomic_read_u64(&bufHdr->state) & BM_CHECKPOINT_NEEDED)
 		{
 			if (SyncOneBuffer(buf_id, false, &wb_context) & BUF_WRITTEN)
 			{
@@ -4015,7 +4015,7 @@ SyncOneBuffer(int buf_id, bool skip_recently_used, WritebackContext *wb_context)
 {
 	BufferDesc *bufHdr = GetBufferDescriptor(buf_id);
 	int			result = 0;
-	uint32		buf_state;
+	uint64		buf_state;
 	BufferTag	tag;
 
 	/* Make sure we can handle the pin */
@@ -4264,7 +4264,7 @@ DebugPrintBufferRefcount(Buffer buffer)
 	int32		loccount;
 	char	   *result;
 	ProcNumber	backend;
-	uint32		buf_state;
+	uint64		buf_state;
 
 	Assert(BufferIsValid(buffer));
 	if (BufferIsLocal(buffer))
@@ -4281,9 +4281,9 @@ DebugPrintBufferRefcount(Buffer buffer)
 	}
 
 	/* theoretically we should lock the bufHdr here */
-	buf_state = pg_atomic_read_u32(&buf->state);
+	buf_state = pg_atomic_read_u64(&buf->state);
 
-	result = psprintf("[%03d] (rel=%s, blockNum=%u, flags=0x%x, refcount=%u %d)",
+	result = psprintf("[%03d] (rel=%s, blockNum=%u, flags=0x%" PRIx64 ", refcount=%u %d)",
 					  buffer,
 					  relpathbackend(BufTagGetRelFileLocator(&buf->tag), backend,
 									 BufTagGetForkNum(&buf->tag)).str,
@@ -4383,7 +4383,7 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object,
 	instr_time	io_start;
 	Block		bufBlock;
 	char	   *bufToWrite;
-	uint32		buf_state;
+	uint64		buf_state;
 
 	/*
 	 * Try to start an I/O operation.  If StartBufferIO returns false, then
@@ -4581,7 +4581,7 @@ BufferIsPermanent(Buffer buffer)
 	 * not random garbage.
 	 */
 	bufHdr = GetBufferDescriptor(buffer - 1);
-	return (pg_atomic_read_u32(&bufHdr->state) & BM_PERMANENT) != 0;
+	return (pg_atomic_read_u64(&bufHdr->state) & BM_PERMANENT) != 0;
 }
 
 /*
@@ -5044,11 +5044,11 @@ FlushRelationBuffers(Relation rel)
 	{
 		for (i = 0; i < NLocBuffer; i++)
 		{
-			uint32		buf_state;
+			uint64		buf_state;
 
 			bufHdr = GetLocalBufferDescriptor(i);
 			if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rel->rd_locator) &&
-				((buf_state = pg_atomic_read_u32(&bufHdr->state)) &
+				((buf_state = pg_atomic_read_u64(&bufHdr->state)) &
 				 (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
 			{
 				ErrorContextCallback errcallback;
@@ -5084,7 +5084,7 @@ FlushRelationBuffers(Relation rel)
 
 	for (i = 0; i < NBuffers; i++)
 	{
-		uint32		buf_state;
+		uint64		buf_state;
 
 		bufHdr = GetBufferDescriptor(i);
 
@@ -5156,7 +5156,7 @@ FlushRelationsAllBuffers(SMgrRelation *smgrs, int nrels)
 	{
 		SMgrSortArray *srelent = NULL;
 		BufferDesc *bufHdr = GetBufferDescriptor(i);
-		uint32		buf_state;
+		uint64		buf_state;
 
 		/*
 		 * As in DropRelationBuffers, an unlocked precheck should be safe and
@@ -5405,7 +5405,7 @@ FlushDatabaseBuffers(Oid dbid)
 
 	for (i = 0; i < NBuffers; i++)
 	{
-		uint32		buf_state;
+		uint64		buf_state;
 
 		bufHdr = GetBufferDescriptor(i);
 
@@ -5553,13 +5553,13 @@ MarkBufferDirtyHint(Buffer buffer, bool buffer_std)
 	 * is only intended to be used in cases where failing to write out the
 	 * data would be harmless anyway, it doesn't really matter.
 	 */
-	if ((pg_atomic_read_u32(&bufHdr->state) & (BM_DIRTY | BM_JUST_DIRTIED)) !=
+	if ((pg_atomic_read_u64(&bufHdr->state) & (BM_DIRTY | BM_JUST_DIRTIED)) !=
 		(BM_DIRTY | BM_JUST_DIRTIED))
 	{
 		XLogRecPtr	lsn = InvalidXLogRecPtr;
 		bool		dirtied = false;
 		bool		delayChkptFlags = false;
-		uint32		buf_state;
+		uint64		buf_state;
 
 		/*
 		 * If we need to protect hint bit updates from torn writes, WAL-log a
@@ -5571,7 +5571,7 @@ MarkBufferDirtyHint(Buffer buffer, bool buffer_std)
 		 * when we call XLogInsert() since the value changes dynamically.
 		 */
 		if (XLogHintBitIsNeeded() &&
-			(pg_atomic_read_u32(&bufHdr->state) & BM_PERMANENT))
+			(pg_atomic_read_u64(&bufHdr->state) & BM_PERMANENT))
 		{
 			/*
 			 * If we must not write WAL, due to a relfilelocator-specific
@@ -5671,8 +5671,8 @@ UnlockBuffers(void)
 
 	if (buf)
 	{
-		uint32		buf_state;
-		uint32		unset_bits = 0;
+		uint64		buf_state;
+		uint64		unset_bits = 0;
 
 		buf_state = LockBufHdr(buf);
 
@@ -5803,8 +5803,8 @@ LockBufferForCleanup(Buffer buffer)
 
 	for (;;)
 	{
-		uint32		buf_state;
-		uint32		unset_bits = 0;
+		uint64		buf_state;
+		uint64		unset_bits = 0;
 
 		/* Try to acquire lock */
 		LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
@@ -5952,7 +5952,7 @@ bool
 ConditionalLockBufferForCleanup(Buffer buffer)
 {
 	BufferDesc *bufHdr;
-	uint32		buf_state,
+	uint64		buf_state,
 				refcount;
 
 	Assert(BufferIsValid(buffer));
@@ -6010,7 +6010,7 @@ bool
 IsBufferCleanupOK(Buffer buffer)
 {
 	BufferDesc *bufHdr;
-	uint32		buf_state;
+	uint64		buf_state;
 
 	Assert(BufferIsValid(buffer));
 
@@ -6066,7 +6066,7 @@ WaitIO(BufferDesc *buf)
 	ConditionVariablePrepareToSleep(cv);
 	for (;;)
 	{
-		uint32		buf_state;
+		uint64		buf_state;
 		PgAioWaitRef iow;
 
 		/*
@@ -6140,7 +6140,7 @@ WaitIO(BufferDesc *buf)
 bool
 StartBufferIO(BufferDesc *buf, bool forInput, bool nowait)
 {
-	uint32		buf_state;
+	uint64		buf_state;
 
 	ResourceOwnerEnlarge(CurrentResourceOwner);
 
@@ -6196,11 +6196,11 @@ StartBufferIO(BufferDesc *buf, bool forInput, bool nowait)
  * is being released)
  */
 void
-TerminateBufferIO(BufferDesc *buf, bool clear_dirty, uint32 set_flag_bits,
+TerminateBufferIO(BufferDesc *buf, bool clear_dirty, uint64 set_flag_bits,
 				  bool forget_owner, bool release_aio)
 {
-	uint32		buf_state;
-	uint32		unset_flag_bits = 0;
+	uint64		buf_state;
+	uint64		unset_flag_bits = 0;
 	int			refcount_change = 0;
 
 	buf_state = LockBufHdr(buf);
@@ -6261,7 +6261,7 @@ static void
 AbortBufferIO(Buffer buffer)
 {
 	BufferDesc *buf_hdr = GetBufferDescriptor(buffer - 1);
-	uint32		buf_state;
+	uint64		buf_state;
 
 	buf_state = LockBufHdr(buf_hdr);
 	Assert(buf_state & (BM_IO_IN_PROGRESS | BM_TAG_VALID));
@@ -6355,10 +6355,10 @@ rlocator_comparator(const void *p1, const void *p2)
 /*
  * Lock buffer header - set BM_LOCKED in buffer state.
  */
-uint32
+uint64
 LockBufHdr(BufferDesc *desc)
 {
-	uint32		old_buf_state;
+	uint64		old_buf_state;
 
 	Assert(!BufferIsLocal(BufferDescriptorGetBuffer(desc)));
 
@@ -6369,7 +6369,7 @@ LockBufHdr(BufferDesc *desc)
 		 * the spin-delay infrastructure. The work necessary for that shows up
 		 * in profiles and is rarely necessary.
 		 */
-		old_buf_state = pg_atomic_fetch_or_u32(&desc->state, BM_LOCKED);
+		old_buf_state = pg_atomic_fetch_or_u64(&desc->state, BM_LOCKED);
 		if (likely(!(old_buf_state & BM_LOCKED)))
 			break;				/* got lock */
 
@@ -6382,7 +6382,7 @@ LockBufHdr(BufferDesc *desc)
 			while (old_buf_state & BM_LOCKED)
 			{
 				perform_spin_delay(&delayStatus);
-				old_buf_state = pg_atomic_read_u32(&desc->state);
+				old_buf_state = pg_atomic_read_u64(&desc->state);
 			}
 			finish_spin_delay(&delayStatus);
 		}
@@ -6403,20 +6403,20 @@ LockBufHdr(BufferDesc *desc)
  * Obviously the buffer could be locked by the time the value is returned, so
  * this is primarily useful in CAS style loops.
  */
-pg_noinline uint32
+pg_noinline uint64
 WaitBufHdrUnlocked(BufferDesc *buf)
 {
 	SpinDelayStatus delayStatus;
-	uint32		buf_state;
+	uint64		buf_state;
 
 	init_local_spin_delay(&delayStatus);
 
-	buf_state = pg_atomic_read_u32(&buf->state);
+	buf_state = pg_atomic_read_u64(&buf->state);
 
 	while (buf_state & BM_LOCKED)
 	{
 		perform_spin_delay(&delayStatus);
-		buf_state = pg_atomic_read_u32(&buf->state);
+		buf_state = pg_atomic_read_u64(&buf->state);
 	}
 
 	finish_spin_delay(&delayStatus);
@@ -6704,12 +6704,12 @@ ResOwnerPrintBufferPin(Datum res)
 static bool
 EvictUnpinnedBufferInternal(BufferDesc *desc, bool *buffer_flushed)
 {
-	uint32		buf_state;
+	uint64		buf_state;
 	bool		result;
 
 	*buffer_flushed = false;
 
-	buf_state = pg_atomic_read_u32(&(desc->state));
+	buf_state = pg_atomic_read_u64(&(desc->state));
 	Assert(buf_state & BM_LOCKED);
 
 	if ((buf_state & BM_VALID) == 0)
@@ -6803,12 +6803,12 @@ EvictAllUnpinnedBuffers(int32 *buffers_evicted, int32 *buffers_flushed,
 	for (int buf = 1; buf <= NBuffers; buf++)
 	{
 		BufferDesc *desc = GetBufferDescriptor(buf - 1);
-		uint32		buf_state;
+		uint64		buf_state;
 		bool		buffer_flushed;
 
 		CHECK_FOR_INTERRUPTS();
 
-		buf_state = pg_atomic_read_u32(&desc->state);
+		buf_state = pg_atomic_read_u64(&desc->state);
 		if (!(buf_state & BM_VALID))
 			continue;
 
@@ -6855,7 +6855,7 @@ EvictRelUnpinnedBuffers(Relation rel, int32 *buffers_evicted,
 	for (int buf = 1; buf <= NBuffers; buf++)
 	{
 		BufferDesc *desc = GetBufferDescriptor(buf - 1);
-		uint32		buf_state = pg_atomic_read_u32(&(desc->state));
+		uint64		buf_state = pg_atomic_read_u64(&(desc->state));
 		bool		buffer_flushed;
 
 		CHECK_FOR_INTERRUPTS();
@@ -6897,12 +6897,12 @@ static bool
 MarkDirtyUnpinnedBufferInternal(Buffer buf, BufferDesc *desc,
 								bool *buffer_already_dirty)
 {
-	uint32		buf_state;
+	uint64		buf_state;
 	bool		result = false;
 
 	*buffer_already_dirty = false;
 
-	buf_state = pg_atomic_read_u32(&(desc->state));
+	buf_state = pg_atomic_read_u64(&(desc->state));
 	Assert(buf_state & BM_LOCKED);
 
 	if ((buf_state & BM_VALID) == 0)
@@ -7000,7 +7000,7 @@ MarkDirtyRelUnpinnedBuffers(Relation rel,
 	for (int buf = 1; buf <= NBuffers; buf++)
 	{
 		BufferDesc *desc = GetBufferDescriptor(buf - 1);
-		uint32		buf_state = pg_atomic_read_u32(&(desc->state));
+		uint64		buf_state = pg_atomic_read_u64(&(desc->state));
 		bool		buffer_already_dirty;
 
 		CHECK_FOR_INTERRUPTS();
@@ -7054,12 +7054,12 @@ MarkDirtyAllUnpinnedBuffers(int32 *buffers_dirtied,
 	for (int buf = 1; buf <= NBuffers; buf++)
 	{
 		BufferDesc *desc = GetBufferDescriptor(buf - 1);
-		uint32		buf_state;
+		uint64		buf_state;
 		bool		buffer_already_dirty;
 
 		CHECK_FOR_INTERRUPTS();
 
-		buf_state = pg_atomic_read_u32(&desc->state);
+		buf_state = pg_atomic_read_u64(&desc->state);
 		if (!(buf_state & BM_VALID))
 			continue;
 
@@ -7110,7 +7110,7 @@ buffer_stage_common(PgAioHandle *ioh, bool is_write, bool is_temp)
 		BufferDesc *buf_hdr = is_temp ?
 			GetLocalBufferDescriptor(-buffer - 1)
 			: GetBufferDescriptor(buffer - 1);
-		uint32		buf_state;
+		uint64		buf_state;
 
 		/*
 		 * Check that all the buffers are actually ones that could conceivably
@@ -7128,7 +7128,7 @@ buffer_stage_common(PgAioHandle *ioh, bool is_write, bool is_temp)
 		}
 
 		if (is_temp)
-			buf_state = pg_atomic_read_u32(&buf_hdr->state);
+			buf_state = pg_atomic_read_u64(&buf_hdr->state);
 		else
 			buf_state = LockBufHdr(buf_hdr);
 
@@ -7166,7 +7166,7 @@ buffer_stage_common(PgAioHandle *ioh, bool is_write, bool is_temp)
 		if (is_temp)
 		{
 			buf_state += BUF_REFCOUNT_ONE;
-			pg_atomic_unlocked_write_u32(&buf_hdr->state, buf_state);
+			pg_atomic_unlocked_write_u64(&buf_hdr->state, buf_state);
 		}
 		else
 			UnlockBufHdrExt(buf_hdr, buf_state, 0, 0, 1);
@@ -7352,13 +7352,13 @@ buffer_readv_complete_one(PgAioTargetData *td, uint8 buf_off, Buffer buffer,
 		: GetBufferDescriptor(buffer - 1);
 	BufferTag	tag = buf_hdr->tag;
 	char	   *bufdata = BufferGetBlock(buffer);
-	uint32		set_flag_bits;
+	uint64		set_flag_bits;
 	int			piv_flags;
 
 	/* check that the buffer is in the expected state for a read */
 #ifdef USE_ASSERT_CHECKING
 	{
-		uint32		buf_state = pg_atomic_read_u32(&buf_hdr->state);
+		uint64		buf_state = pg_atomic_read_u64(&buf_hdr->state);
 
 		Assert(buf_state & BM_TAG_VALID);
 		Assert(!(buf_state & BM_VALID));
diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c
index 9a93fb335fc..b7687836188 100644
--- a/src/backend/storage/buffer/freelist.c
+++ b/src/backend/storage/buffer/freelist.c
@@ -86,7 +86,7 @@ typedef struct BufferAccessStrategyData
 
 /* Prototypes for internal functions */
 static BufferDesc *GetBufferFromRing(BufferAccessStrategy strategy,
-									 uint32 *buf_state);
+									 uint64 *buf_state);
 static void AddBufferToRing(BufferAccessStrategy strategy,
 							BufferDesc *buf);
 
@@ -171,7 +171,7 @@ ClockSweepTick(void)
  *	before returning.
  */
 BufferDesc *
-StrategyGetBuffer(BufferAccessStrategy strategy, uint32 *buf_state, bool *from_ring)
+StrategyGetBuffer(BufferAccessStrategy strategy, uint64 *buf_state, bool *from_ring)
 {
 	BufferDesc *buf;
 	int			bgwprocno;
@@ -230,8 +230,8 @@ StrategyGetBuffer(BufferAccessStrategy strategy, uint32 *buf_state, bool *from_r
 	trycounter = NBuffers;
 	for (;;)
 	{
-		uint32		old_buf_state;
-		uint32		local_buf_state;
+		uint64		old_buf_state;
+		uint64		local_buf_state;
 
 		buf = GetBufferDescriptor(ClockSweepTick());
 
@@ -239,7 +239,7 @@ StrategyGetBuffer(BufferAccessStrategy strategy, uint32 *buf_state, bool *from_r
 		 * Check whether the buffer can be used and pin it if so. Do this
 		 * using a CAS loop, to avoid having to lock the buffer header.
 		 */
-		old_buf_state = pg_atomic_read_u32(&buf->state);
+		old_buf_state = pg_atomic_read_u64(&buf->state);
 		for (;;)
 		{
 			local_buf_state = old_buf_state;
@@ -277,7 +277,7 @@ StrategyGetBuffer(BufferAccessStrategy strategy, uint32 *buf_state, bool *from_r
 			{
 				local_buf_state -= BUF_USAGECOUNT_ONE;
 
-				if (pg_atomic_compare_exchange_u32(&buf->state, &old_buf_state,
+				if (pg_atomic_compare_exchange_u64(&buf->state, &old_buf_state,
 												   local_buf_state))
 				{
 					trycounter = NBuffers;
@@ -289,7 +289,7 @@ StrategyGetBuffer(BufferAccessStrategy strategy, uint32 *buf_state, bool *from_r
 				/* pin the buffer if the CAS succeeds */
 				local_buf_state += BUF_REFCOUNT_ONE;
 
-				if (pg_atomic_compare_exchange_u32(&buf->state, &old_buf_state,
+				if (pg_atomic_compare_exchange_u64(&buf->state, &old_buf_state,
 												   local_buf_state))
 				{
 					/* Found a usable buffer */
@@ -655,12 +655,12 @@ FreeAccessStrategy(BufferAccessStrategy strategy)
  * returning.
  */
 static BufferDesc *
-GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state)
+GetBufferFromRing(BufferAccessStrategy strategy, uint64 *buf_state)
 {
 	BufferDesc *buf;
 	Buffer		bufnum;
-	uint32		old_buf_state;
-	uint32		local_buf_state;	/* to avoid repeated (de-)referencing */
+	uint64		old_buf_state;
+	uint64		local_buf_state;	/* to avoid repeated (de-)referencing */
 
 
 	/* Advance to next ring slot */
@@ -682,7 +682,7 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state)
 	 * Check whether the buffer can be used and pin it if so. Do this using a
 	 * CAS loop, to avoid having to lock the buffer header.
 	 */
-	old_buf_state = pg_atomic_read_u32(&buf->state);
+	old_buf_state = pg_atomic_read_u64(&buf->state);
 	for (;;)
 	{
 		local_buf_state = old_buf_state;
@@ -710,7 +710,7 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state)
 		/* pin the buffer if the CAS succeeds */
 		local_buf_state += BUF_REFCOUNT_ONE;
 
-		if (pg_atomic_compare_exchange_u32(&buf->state, &old_buf_state,
+		if (pg_atomic_compare_exchange_u64(&buf->state, &old_buf_state,
 										   local_buf_state))
 		{
 			*buf_state = local_buf_state;
diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index f6e2b1aa288..04a540379a2 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -148,7 +148,7 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
 	}
 	else
 	{
-		uint32		buf_state;
+		uint64		buf_state;
 
 		victim_buffer = GetLocalVictimBuffer();
 		bufid = -victim_buffer - 1;
@@ -165,10 +165,10 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
 		 */
 		bufHdr->tag = newTag;
 
-		buf_state = pg_atomic_read_u32(&bufHdr->state);
+		buf_state = pg_atomic_read_u64(&bufHdr->state);
 		buf_state &= ~(BUF_FLAG_MASK | BUF_USAGECOUNT_MASK);
 		buf_state |= BM_TAG_VALID | BUF_USAGECOUNT_ONE;
-		pg_atomic_unlocked_write_u32(&bufHdr->state, buf_state);
+		pg_atomic_unlocked_write_u64(&bufHdr->state, buf_state);
 
 		*foundPtr = false;
 	}
@@ -245,12 +245,12 @@ GetLocalVictimBuffer(void)
 
 		if (LocalRefCount[victim_bufid] == 0)
 		{
-			uint32		buf_state = pg_atomic_read_u32(&bufHdr->state);
+			uint64		buf_state = pg_atomic_read_u64(&bufHdr->state);
 
 			if (BUF_STATE_GET_USAGECOUNT(buf_state) > 0)
 			{
 				buf_state -= BUF_USAGECOUNT_ONE;
-				pg_atomic_unlocked_write_u32(&bufHdr->state, buf_state);
+				pg_atomic_unlocked_write_u64(&bufHdr->state, buf_state);
 				trycounter = NLocBuffer;
 			}
 			else if (BUF_STATE_GET_REFCOUNT(buf_state) > 0)
@@ -286,13 +286,13 @@ GetLocalVictimBuffer(void)
 	 * this buffer is not referenced but it might still be dirty. if that's
 	 * the case, write it out before reusing it!
 	 */
-	if (pg_atomic_read_u32(&bufHdr->state) & BM_DIRTY)
+	if (pg_atomic_read_u64(&bufHdr->state) & BM_DIRTY)
 		FlushLocalBuffer(bufHdr, NULL);
 
 	/*
 	 * Remove the victim buffer from the hashtable and mark as invalid.
 	 */
-	if (pg_atomic_read_u32(&bufHdr->state) & BM_TAG_VALID)
+	if (pg_atomic_read_u64(&bufHdr->state) & BM_TAG_VALID)
 	{
 		InvalidateLocalBuffer(bufHdr, false);
 
@@ -417,7 +417,7 @@ ExtendBufferedRelLocal(BufferManagerRelation bmr,
 		if (found)
 		{
 			BufferDesc *existing_hdr;
-			uint32		buf_state;
+			uint64		buf_state;
 
 			UnpinLocalBuffer(BufferDescriptorGetBuffer(victim_buf_hdr));
 
@@ -428,18 +428,18 @@ ExtendBufferedRelLocal(BufferManagerRelation bmr,
 			/*
 			 * Clear the BM_VALID bit, do StartLocalBufferIO() and proceed.
 			 */
-			buf_state = pg_atomic_read_u32(&existing_hdr->state);
+			buf_state = pg_atomic_read_u64(&existing_hdr->state);
 			Assert(buf_state & BM_TAG_VALID);
 			Assert(!(buf_state & BM_DIRTY));
 			buf_state &= ~BM_VALID;
-			pg_atomic_unlocked_write_u32(&existing_hdr->state, buf_state);
+			pg_atomic_unlocked_write_u64(&existing_hdr->state, buf_state);
 
 			/* no need to loop for local buffers */
 			StartLocalBufferIO(existing_hdr, true, false);
 		}
 		else
 		{
-			uint32		buf_state = pg_atomic_read_u32(&victim_buf_hdr->state);
+			uint64		buf_state = pg_atomic_read_u64(&victim_buf_hdr->state);
 
 			Assert(!(buf_state & (BM_VALID | BM_TAG_VALID | BM_DIRTY | BM_JUST_DIRTIED)));
 
@@ -447,7 +447,7 @@ ExtendBufferedRelLocal(BufferManagerRelation bmr,
 
 			buf_state |= BM_TAG_VALID | BUF_USAGECOUNT_ONE;
 
-			pg_atomic_unlocked_write_u32(&victim_buf_hdr->state, buf_state);
+			pg_atomic_unlocked_write_u64(&victim_buf_hdr->state, buf_state);
 
 			hresult->id = victim_buf_id;
 
@@ -467,13 +467,13 @@ ExtendBufferedRelLocal(BufferManagerRelation bmr,
 	{
 		Buffer		buf = buffers[i];
 		BufferDesc *buf_hdr;
-		uint32		buf_state;
+		uint64		buf_state;
 
 		buf_hdr = GetLocalBufferDescriptor(-buf - 1);
 
-		buf_state = pg_atomic_read_u32(&buf_hdr->state);
+		buf_state = pg_atomic_read_u64(&buf_hdr->state);
 		buf_state |= BM_VALID;
-		pg_atomic_unlocked_write_u32(&buf_hdr->state, buf_state);
+		pg_atomic_unlocked_write_u64(&buf_hdr->state, buf_state);
 	}
 
 	*extended_by = extend_by;
@@ -492,7 +492,7 @@ MarkLocalBufferDirty(Buffer buffer)
 {
 	int			bufid;
 	BufferDesc *bufHdr;
-	uint32		buf_state;
+	uint64		buf_state;
 
 	Assert(BufferIsLocal(buffer));
 
@@ -506,14 +506,14 @@ MarkLocalBufferDirty(Buffer buffer)
 
 	bufHdr = GetLocalBufferDescriptor(bufid);
 
-	buf_state = pg_atomic_read_u32(&bufHdr->state);
+	buf_state = pg_atomic_read_u64(&bufHdr->state);
 
 	if (!(buf_state & BM_DIRTY))
 		pgBufferUsage.local_blks_dirtied++;
 
 	buf_state |= BM_DIRTY;
 
-	pg_atomic_unlocked_write_u32(&bufHdr->state, buf_state);
+	pg_atomic_unlocked_write_u64(&bufHdr->state, buf_state);
 }
 
 /*
@@ -522,7 +522,7 @@ MarkLocalBufferDirty(Buffer buffer)
 bool
 StartLocalBufferIO(BufferDesc *bufHdr, bool forInput, bool nowait)
 {
-	uint32		buf_state;
+	uint64		buf_state;
 
 	/*
 	 * With AIO the buffer could have IO in progress, e.g. when there are two
@@ -542,7 +542,7 @@ StartLocalBufferIO(BufferDesc *bufHdr, bool forInput, bool nowait)
 	/* Once we get here, there is definitely no I/O active on this buffer */
 
 	/* Check if someone else already did the I/O */
-	buf_state = pg_atomic_read_u32(&bufHdr->state);
+	buf_state = pg_atomic_read_u64(&bufHdr->state);
 	if (forInput ? (buf_state & BM_VALID) : !(buf_state & BM_DIRTY))
 	{
 		return false;
@@ -559,11 +559,11 @@ StartLocalBufferIO(BufferDesc *bufHdr, bool forInput, bool nowait)
  * Like TerminateBufferIO, but for local buffers
  */
 void
-TerminateLocalBufferIO(BufferDesc *bufHdr, bool clear_dirty, uint32 set_flag_bits,
+TerminateLocalBufferIO(BufferDesc *bufHdr, bool clear_dirty, uint64 set_flag_bits,
 					   bool release_aio)
 {
 	/* Only need to adjust flags */
-	uint32		buf_state = pg_atomic_read_u32(&bufHdr->state);
+	uint64		buf_state = pg_atomic_read_u64(&bufHdr->state);
 
 	/* BM_IO_IN_PROGRESS isn't currently used for local buffers */
 
@@ -582,7 +582,7 @@ TerminateLocalBufferIO(BufferDesc *bufHdr, bool clear_dirty, uint32 set_flag_bit
 	}
 
 	buf_state |= set_flag_bits;
-	pg_atomic_unlocked_write_u32(&bufHdr->state, buf_state);
+	pg_atomic_unlocked_write_u64(&bufHdr->state, buf_state);
 
 	/* local buffers don't track IO using resowners */
 
@@ -606,7 +606,7 @@ InvalidateLocalBuffer(BufferDesc *bufHdr, bool check_unreferenced)
 {
 	Buffer		buffer = BufferDescriptorGetBuffer(bufHdr);
 	int			bufid = -buffer - 1;
-	uint32		buf_state;
+	uint64		buf_state;
 	LocalBufferLookupEnt *hresult;
 
 	/*
@@ -622,7 +622,7 @@ InvalidateLocalBuffer(BufferDesc *bufHdr, bool check_unreferenced)
 		Assert(!pgaio_wref_valid(&bufHdr->io_wref));
 	}
 
-	buf_state = pg_atomic_read_u32(&bufHdr->state);
+	buf_state = pg_atomic_read_u64(&bufHdr->state);
 
 	/*
 	 * We need to test not just LocalRefCount[bufid] but also the BufferDesc
@@ -647,7 +647,7 @@ InvalidateLocalBuffer(BufferDesc *bufHdr, bool check_unreferenced)
 	ClearBufferTag(&bufHdr->tag);
 	buf_state &= ~BUF_FLAG_MASK;
 	buf_state &= ~BUF_USAGECOUNT_MASK;
-	pg_atomic_unlocked_write_u32(&bufHdr->state, buf_state);
+	pg_atomic_unlocked_write_u64(&bufHdr->state, buf_state);
 }
 
 /*
@@ -671,9 +671,9 @@ DropRelationLocalBuffers(RelFileLocator rlocator, ForkNumber *forkNum,
 	for (i = 0; i < NLocBuffer; i++)
 	{
 		BufferDesc *bufHdr = GetLocalBufferDescriptor(i);
-		uint32		buf_state;
+		uint64		buf_state;
 
-		buf_state = pg_atomic_read_u32(&bufHdr->state);
+		buf_state = pg_atomic_read_u64(&bufHdr->state);
 
 		if (!(buf_state & BM_TAG_VALID) ||
 			!BufTagMatchesRelFileLocator(&bufHdr->tag, &rlocator))
@@ -706,9 +706,9 @@ DropRelationAllLocalBuffers(RelFileLocator rlocator)
 	for (i = 0; i < NLocBuffer; i++)
 	{
 		BufferDesc *bufHdr = GetLocalBufferDescriptor(i);
-		uint32		buf_state;
+		uint64		buf_state;
 
-		buf_state = pg_atomic_read_u32(&bufHdr->state);
+		buf_state = pg_atomic_read_u64(&bufHdr->state);
 
 		if ((buf_state & BM_TAG_VALID) &&
 			BufTagMatchesRelFileLocator(&bufHdr->tag, &rlocator))
@@ -804,11 +804,11 @@ InitLocalBuffers(void)
 bool
 PinLocalBuffer(BufferDesc *buf_hdr, bool adjust_usagecount)
 {
-	uint32		buf_state;
+	uint64		buf_state;
 	Buffer		buffer = BufferDescriptorGetBuffer(buf_hdr);
 	int			bufid = -buffer - 1;
 
-	buf_state = pg_atomic_read_u32(&buf_hdr->state);
+	buf_state = pg_atomic_read_u64(&buf_hdr->state);
 
 	if (LocalRefCount[bufid] == 0)
 	{
@@ -819,7 +819,7 @@ PinLocalBuffer(BufferDesc *buf_hdr, bool adjust_usagecount)
 		{
 			buf_state += BUF_USAGECOUNT_ONE;
 		}
-		pg_atomic_unlocked_write_u32(&buf_hdr->state, buf_state);
+		pg_atomic_unlocked_write_u64(&buf_hdr->state, buf_state);
 
 		/*
 		 * See comment in PinBuffer().
@@ -856,14 +856,14 @@ UnpinLocalBufferNoOwner(Buffer buffer)
 	if (--LocalRefCount[buffid] == 0)
 	{
 		BufferDesc *buf_hdr = GetLocalBufferDescriptor(buffid);
-		uint32		buf_state;
+		uint64		buf_state;
 
 		NLocalPinnedBuffers--;
 
-		buf_state = pg_atomic_read_u32(&buf_hdr->state);
+		buf_state = pg_atomic_read_u64(&buf_hdr->state);
 		Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
 		buf_state -= BUF_REFCOUNT_ONE;
-		pg_atomic_unlocked_write_u32(&buf_hdr->state, buf_state);
+		pg_atomic_unlocked_write_u64(&buf_hdr->state, buf_state);
 
 		/* see comment in UnpinBufferNoOwner */
 		VALGRIND_MAKE_MEM_NOACCESS(LocalBufHdrGetBlock(buf_hdr), BLCKSZ);
diff --git a/src/include/storage/buf_internals.h b/src/include/storage/buf_internals.h
index 2f607ea2ac5..e6e788224f5 100644
--- a/src/include/storage/buf_internals.h
+++ b/src/include/storage/buf_internals.h
@@ -30,7 +30,7 @@
 #include "utils/resowner.h"
 
 /*
- * Buffer state is a single 32-bit variable where following data is combined.
+ * Buffer state is a single 64-bit variable where following data is combined.
  *
  * State of the buffer itself (in order):
  * - 18 bits refcount
@@ -40,6 +40,9 @@
  * Combining these values allows to perform some operations without locking
  * the buffer header, by modifying them together with a CAS loop.
  *
+ * NB: A future commit will use a significant portion of the remaining bits to
+ * implement buffer locking as part of the state variable.
+ *
  * The definition of buffer state components is below.
  */
 #define BUF_REFCOUNT_BITS 18
@@ -52,27 +55,27 @@ StaticAssertDecl(BUF_REFCOUNT_BITS + BUF_USAGECOUNT_BITS + BUF_FLAG_BITS == 32,
 /* refcount related definitions */
 #define BUF_REFCOUNT_ONE 1
 #define BUF_REFCOUNT_MASK \
-	((1U << BUF_REFCOUNT_BITS) - 1)
+	((UINT64CONST(1) << BUF_REFCOUNT_BITS) - 1)
 
 /* usage count related definitions */
 #define BUF_USAGECOUNT_SHIFT \
 	BUF_REFCOUNT_BITS
 #define BUF_USAGECOUNT_MASK \
-	(((1U << BUF_USAGECOUNT_BITS) - 1) << (BUF_USAGECOUNT_SHIFT))
+	(((UINT64CONST(1) << BUF_USAGECOUNT_BITS) - 1) << (BUF_USAGECOUNT_SHIFT))
 #define BUF_USAGECOUNT_ONE \
-	(1U << BUF_REFCOUNT_BITS)
+	(UINT64CONST(1) << BUF_REFCOUNT_BITS)
 
 /* flags related definitions */
 #define BUF_FLAG_SHIFT \
 	(BUF_REFCOUNT_BITS + BUF_USAGECOUNT_BITS)
 #define BUF_FLAG_MASK \
-	(((1U << BUF_FLAG_BITS) - 1) << BUF_FLAG_SHIFT)
+	(((UINT64CONST(1) << BUF_FLAG_BITS) - 1) << BUF_FLAG_SHIFT)
 
 /* Get refcount and usagecount from buffer state */
 #define BUF_STATE_GET_REFCOUNT(state) \
-	((state) & BUF_REFCOUNT_MASK)
+	((uint32)((state) & BUF_REFCOUNT_MASK))
 #define BUF_STATE_GET_USAGECOUNT(state) \
-	(((state) & BUF_USAGECOUNT_MASK) >> BUF_USAGECOUNT_SHIFT)
+	((uint32)(((state) & BUF_USAGECOUNT_MASK) >> BUF_USAGECOUNT_SHIFT))
 
 /*
  * Flags for buffer descriptors
@@ -82,7 +85,7 @@ StaticAssertDecl(BUF_REFCOUNT_BITS + BUF_USAGECOUNT_BITS + BUF_FLAG_BITS == 32,
  */
 
 #define BUF_DEFINE_FLAG(flagno)	\
-	(1U << (BUF_REFCOUNT_BITS + BUF_USAGECOUNT_BITS + (flagno)))
+	(UINT64CONST(1) << (BUF_FLAG_SHIFT + (flagno)))
 
 /* buffer header is locked */
 #define BM_LOCKED					BUF_DEFINE_FLAG( 0)
@@ -115,7 +118,7 @@ StaticAssertDecl(BUF_REFCOUNT_BITS + BUF_USAGECOUNT_BITS + BUF_FLAG_BITS == 32,
  */
 #define BM_MAX_USAGE_COUNT	5
 
-StaticAssertDecl(BM_MAX_USAGE_COUNT < (1 << BUF_USAGECOUNT_BITS),
+StaticAssertDecl(BM_MAX_USAGE_COUNT < (UINT64CONST(1) << BUF_USAGECOUNT_BITS),
 				 "BM_MAX_USAGE_COUNT doesn't fit in BUF_USAGECOUNT_BITS bits");
 StaticAssertDecl(MAX_BACKENDS_BITS <= BUF_REFCOUNT_BITS,
 				 "MAX_BACKENDS_BITS needs to be <= BUF_REFCOUNT_BITS");
@@ -280,8 +283,8 @@ BufMappingPartitionLockByIndex(uint32 index)
  * We use this same struct for local buffer headers, but the locks are not
  * used and not all of the flag bits are useful either. To avoid unnecessary
  * overhead, manipulations of the state field should be done without actual
- * atomic operations (i.e. only pg_atomic_read_u32() and
- * pg_atomic_unlocked_write_u32()).
+ * atomic operations (i.e. only pg_atomic_read_u64() and
+ * pg_atomic_unlocked_write_u64()).
  *
  * Be careful to avoid increasing the size of the struct when adding or
  * reordering members.  Keeping it below 64 bytes (the most common CPU
@@ -309,7 +312,7 @@ typedef struct BufferDesc
 	 * State of the buffer, containing flags, refcount and usagecount. See
 	 * BUF_* and BM_* defines at the top of this file.
 	 */
-	pg_atomic_uint32 state;
+	pg_atomic_uint64 state;
 
 	/*
 	 * Backend of pin-count waiter. The buffer header spinlock needs to be
@@ -415,7 +418,7 @@ BufferDescriptorGetContentLock(const BufferDesc *bdesc)
  * Functions for acquiring/releasing a shared buffer header's spinlock.  Do
  * not apply these to local buffers!
  */
-extern uint32 LockBufHdr(BufferDesc *desc);
+extern uint64 LockBufHdr(BufferDesc *desc);
 
 /*
  * Unlock the buffer header.
@@ -426,9 +429,9 @@ extern uint32 LockBufHdr(BufferDesc *desc);
 static inline void
 UnlockBufHdr(BufferDesc *desc)
 {
-	Assert(pg_atomic_read_u32(&desc->state) & BM_LOCKED);
+	Assert(pg_atomic_read_u64(&desc->state) & BM_LOCKED);
 
-	pg_atomic_fetch_sub_u32(&desc->state, BM_LOCKED);
+	pg_atomic_fetch_sub_u64(&desc->state, BM_LOCKED);
 }
 
 /*
@@ -439,14 +442,14 @@ UnlockBufHdr(BufferDesc *desc)
  * Note that this approach would not work for usagecount, since we need to cap
  * the usagecount at BM_MAX_USAGE_COUNT.
  */
-static inline uint32
-UnlockBufHdrExt(BufferDesc *desc, uint32 old_buf_state,
-				uint32 set_bits, uint32 unset_bits,
+static inline uint64
+UnlockBufHdrExt(BufferDesc *desc, uint64 old_buf_state,
+				uint64 set_bits, uint64 unset_bits,
 				int refcount_change)
 {
 	for (;;)
 	{
-		uint32		buf_state = old_buf_state;
+		uint64		buf_state = old_buf_state;
 
 		Assert(buf_state & BM_LOCKED);
 
@@ -457,7 +460,7 @@ UnlockBufHdrExt(BufferDesc *desc, uint32 old_buf_state,
 		if (refcount_change != 0)
 			buf_state += BUF_REFCOUNT_ONE * refcount_change;
 
-		if (pg_atomic_compare_exchange_u32(&desc->state, &old_buf_state,
+		if (pg_atomic_compare_exchange_u64(&desc->state, &old_buf_state,
 										   buf_state))
 		{
 			return old_buf_state;
@@ -465,7 +468,7 @@ UnlockBufHdrExt(BufferDesc *desc, uint32 old_buf_state,
 	}
 }
 
-extern uint32 WaitBufHdrUnlocked(BufferDesc *buf);
+extern uint64 WaitBufHdrUnlocked(BufferDesc *buf);
 
 /* in bufmgr.c */
 
@@ -525,14 +528,14 @@ extern void TrackNewBufferPin(Buffer buf);
 
 /* solely to make it easier to write tests */
 extern bool StartBufferIO(BufferDesc *buf, bool forInput, bool nowait);
-extern void TerminateBufferIO(BufferDesc *buf, bool clear_dirty, uint32 set_flag_bits,
+extern void TerminateBufferIO(BufferDesc *buf, bool clear_dirty, uint64 set_flag_bits,
 							  bool forget_owner, bool release_aio);
 
 
 /* freelist.c */
 extern IOContext IOContextForStrategy(BufferAccessStrategy strategy);
 extern BufferDesc *StrategyGetBuffer(BufferAccessStrategy strategy,
-									 uint32 *buf_state, bool *from_ring);
+									 uint64 *buf_state, bool *from_ring);
 extern bool StrategyRejectBuffer(BufferAccessStrategy strategy,
 								 BufferDesc *buf, bool from_ring);
 
@@ -568,7 +571,7 @@ extern BlockNumber ExtendBufferedRelLocal(BufferManagerRelation bmr,
 										  uint32 *extended_by);
 extern void MarkLocalBufferDirty(Buffer buffer);
 extern void TerminateLocalBufferIO(BufferDesc *bufHdr, bool clear_dirty,
-								   uint32 set_flag_bits, bool release_aio);
+								   uint64 set_flag_bits, bool release_aio);
 extern bool StartLocalBufferIO(BufferDesc *bufHdr, bool forInput, bool nowait);
 extern void FlushLocalBuffer(BufferDesc *bufHdr, SMgrRelation reln);
 extern void InvalidateLocalBuffer(BufferDesc *bufHdr, bool check_unreferenced);
diff --git a/src/include/storage/procnumber.h b/src/include/storage/procnumber.h
index 30c360ad350..bd9cb3891cc 100644
--- a/src/include/storage/procnumber.h
+++ b/src/include/storage/procnumber.h
@@ -27,13 +27,13 @@ typedef int ProcNumber;
 
 /*
  * Note: MAX_BACKENDS_BITS is 18 as that is the space available for buffer
- * refcounts in buf_internals.h.  This limitation could be lifted by using a
- * 64bit state; but it's unlikely to be worthwhile as 2^18-1 backends exceed
- * currently realistic configurations. Even if that limitation were removed,
- * we still could not a) exceed 2^23-1 because inval.c stores the ProcNumber
- * as a 3-byte signed integer, b) INT_MAX/4 because some places compute
- * 4*MaxBackends without any overflow check.  We check that the configured
- * number of backends does not exceed MAX_BACKENDS in InitializeMaxBackends().
+ * refcounts in buf_internals.h.  This limitation could be lifted, but it's
+ * unlikely to be worthwhile as 2^18-1 backends exceed currently realistic
+ * configurations. Even if that limitation were removed, we still could not a)
+ * exceed 2^23-1 because inval.c stores the ProcNumber as a 3-byte signed
+ * integer, b) INT_MAX/4 because some places compute 4*MaxBackends without any
+ * overflow check.  We check that the configured number of backends does not
+ * exceed MAX_BACKENDS in InitializeMaxBackends().
  */
 #define MAX_BACKENDS_BITS		18
 #define MAX_BACKENDS			((1U << MAX_BACKENDS_BITS)-1)
diff --git a/src/test/modules/test_aio/test_aio.c b/src/test/modules/test_aio/test_aio.c
index e046b08f3d5..b1aa8af9ec0 100644
--- a/src/test/modules/test_aio/test_aio.c
+++ b/src/test/modules/test_aio/test_aio.c
@@ -308,9 +308,9 @@ create_toy_buffer(Relation rel, BlockNumber blkno)
 {
 	Buffer		buf;
 	BufferDesc *buf_hdr;
-	uint32		buf_state;
+	uint64		buf_state;
 	bool		was_pinned = false;
-	uint32		unset_bits = 0;
+	uint64		unset_bits = 0;
 
 	/* place buffer in shared buffers without erroring out */
 	buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_ZERO_AND_LOCK, NULL);
@@ -319,7 +319,7 @@ create_toy_buffer(Relation rel, BlockNumber blkno)
 	if (RelationUsesLocalBuffers(rel))
 	{
 		buf_hdr = GetLocalBufferDescriptor(-buf - 1);
-		buf_state = pg_atomic_read_u32(&buf_hdr->state);
+		buf_state = pg_atomic_read_u64(&buf_hdr->state);
 	}
 	else
 	{
@@ -340,7 +340,7 @@ create_toy_buffer(Relation rel, BlockNumber blkno)
 	if (RelationUsesLocalBuffers(rel))
 	{
 		buf_state &= ~unset_bits;
-		pg_atomic_unlocked_write_u32(&buf_hdr->state, buf_state);
+		pg_atomic_unlocked_write_u64(&buf_hdr->state, buf_state);
 	}
 	else
 	{
@@ -489,7 +489,7 @@ invalidate_rel_block(PG_FUNCTION_ARGS)
 
 			LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
 
-			if (pg_atomic_read_u32(&buf_hdr->state) & BM_DIRTY)
+			if (pg_atomic_read_u64(&buf_hdr->state) & BM_DIRTY)
 			{
 				if (BufferIsLocal(buf))
 					FlushLocalBuffer(buf_hdr, NULL);
@@ -572,7 +572,7 @@ buffer_call_terminate_io(PG_FUNCTION_ARGS)
 	bool		io_error = PG_GETARG_BOOL(3);
 	bool		release_aio = PG_GETARG_BOOL(4);
 	bool		clear_dirty = false;
-	uint32		set_flag_bits = 0;
+	uint64		set_flag_bits = 0;
 
 	if (io_error)
 		set_flag_bits |= BM_IO_ERROR;