4 files changed, 28 insertions, 0 deletions
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index f4fab7edfee..34956a5a663 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -1262,6 +1262,11 @@ GetMultiXactIdMembers(MultiXactId multi, MultiXactMember **members,
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),
 				 errmsg("MultiXact %u has invalid next offset", multi)));
+	if (nextMXOffset == offset)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("MultiXact %u with offset (%" PRIu64 ") has zero members",
+						multi, offset)));
 	if (nextMXOffset < offset)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),
diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 956b23816de..642c61fc55c 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -508,8 +508,12 @@ InitializeParallelDSM(ParallelContext *pcxt)
 void
 ReinitializeParallelDSM(ParallelContext *pcxt)
 {
+	MemoryContext oldcontext;
 	FixedParallelState *fps;
 
+	/* We might be running in a very short-lived memory context. */
+	oldcontext = MemoryContextSwitchTo(TopTransactionContext);
+
 	/* Wait for any old workers to exit. */
 	if (pcxt->nworkers_launched > 0)
 	{
@@ -547,6 +551,9 @@ ReinitializeParallelDSM(ParallelContext *pcxt)
 			pcxt->worker[i].error_mqh = shm_mq_attach(mq, pcxt->seg, NULL);
 		}
 	}
+
+	/* Restore previous memory context. */
+	MemoryContextSwitchTo(oldcontext);
 }
 
 /*
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 6a5640df51a..430a38b1a21 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7001,6 +7001,10 @@ CreateCheckPoint(int flags)
 	 */
 	SyncPreCheckpoint();
 
+	/* Run these points outside the critical section. */
+	INJECTION_POINT("create-checkpoint-initial", NULL);
+	INJECTION_POINT_LOAD("create-checkpoint-run");
+
 	/*
 	 * Use a critical section to force system panic if we have trouble.
 	 */
@@ -7151,6 +7155,8 @@ CreateCheckPoint(int flags)
 	if (log_checkpoints)
 		LogCheckpointStart(flags, false);
 
+	INJECTION_POINT_CACHED("create-checkpoint-run", NULL);
+
 	/* Update the process title */
 	update_checkpoint_display(flags, false, false);
 
diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index ae2398d6975..38b594d2170 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -805,6 +805,16 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 		}
 		memcpy(&checkPoint, XLogRecGetData(xlogreader), sizeof(CheckPoint));
 		wasShutdown = ((record->xl_info & ~XLR_INFO_MASK) == XLOG_CHECKPOINT_SHUTDOWN);
+
+		/* Make sure that REDO location exists. */
+		if (checkPoint.redo < CheckPointLoc)
+		{
+			XLogPrefetcherBeginRead(xlogprefetcher, checkPoint.redo);
+			if (!ReadRecord(xlogprefetcher, LOG, false, checkPoint.ThisTimeLineID))
+				ereport(FATAL,
+						errmsg("could not find redo location %X/%08X referenced by checkpoint record at %X/%08X",
+							   LSN_FORMAT_ARGS(checkPoint.redo), LSN_FORMAT_ARGS(CheckPointLoc)));
+		}
 	}
 
 	if (ArchiveRecoveryRequested)