diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 1813f8ca1d..f5c8e9d812 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -5181,7 +5181,7 @@ CountChildren(int target)
 /*
  * StartChildProcess -- start an auxiliary process for the postmaster
  *
- * xlop determines what kind of child will be started.  All child types
+ * "type" determines what kind of child will be started.  All child types
  * initially go to AuxiliaryProcessMain, which will handle common setup.
  *
  * Return value of StartChildProcess is subprocess' PID, or 0 if failed
@@ -5529,9 +5529,19 @@ do_start_bgworker(RegisteredBgWorker *rw)
 			/* Close the postmaster's sockets */
 			ClosePostmasterPorts(false);
 
-			/* Do NOT release postmaster's working memory context */
+			/*
+			 * Before blowing away PostmasterContext, save this bgworker's
+			 * data where it can find it.
+			 */
+			MyBgworkerEntry = (BackgroundWorker *)
+				MemoryContextAlloc(TopMemoryContext, sizeof(BackgroundWorker));
+			memcpy(MyBgworkerEntry, &rw->rw_worker, sizeof(BackgroundWorker));
+
+			/* Release postmaster's working memory context */
+			MemoryContextSwitchTo(TopMemoryContext);
+			MemoryContextDelete(PostmasterContext);
+			PostmasterContext = NULL;
 
-			MyBgworkerEntry = &rw->rw_worker;
 			StartBackgroundWorker();
 			break;
 #endif
@@ -5539,6 +5549,7 @@ do_start_bgworker(RegisteredBgWorker *rw)
 			rw->rw_pid = worker_pid;
 			rw->rw_backend->pid = rw->rw_pid;
 			ReportBackgroundWorkerPID(rw);
+			break;
 	}
 }
 
diff --git a/src/backend/utils/mmgr/README b/src/backend/utils/mmgr/README
index 80a7b6a453..f97d7653de 100644
--- a/src/backend/utils/mmgr/README
+++ b/src/backend/utils/mmgr/README
@@ -160,10 +160,12 @@ running with CurrentMemoryContext pointing here.
 PostmasterContext --- this is the postmaster's normal working context.
 After a backend is spawned, it can delete PostmasterContext to free its
 copy of memory the postmaster was using that it doesn't need.
-(Anything that has to be passed from postmaster to backends is passed
-in TopMemoryContext.  The postmaster has only TopMemoryContext,
-PostmasterContext, and ErrorContext --- the remaining top-level contexts
-are set up in each backend during startup.)
+Note that in non-EXEC_BACKEND builds, the postmaster's copy of pg_hba.conf
+and pg_ident.conf data is used directly during authentication in backend
+processes; so backends can't delete PostmasterContext until that's done.
+(The postmaster has only TopMemoryContext, PostmasterContext, and
+ErrorContext --- the remaining top-level contexts are set up in each
+backend during startup.)
 
 CacheMemoryContext --- permanent storage for relcache, catcache, and
 related modules.  This will never be reset or deleted, either, so it's