From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Fri, 27 Mar 2026 23:02:11 +0000 (+0200)
Subject: Fix RequestNamedLWLockTranche in single-user mode
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2407c8db159dbae5afd23080a92122e1acb2f5c1;p=thirdparty%2Fpostgresql.git

Fix RequestNamedLWLockTranche in single-user mode

PostmasterContext is not available in single-user mode, use
TopMemoryContext instead. Also make sure that we use the correct
memory context in the lappend().

Author: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://www.postgresql.org/message-id/acb_Eo1XtmCO_9z7@nathan
---

diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 7a68071302a..f5b2a6d479d 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -630,6 +630,7 @@ void
 RequestNamedLWLockTranche(const char *tranche_name, int num_lwlocks)
 {
 	NamedLWLockTrancheRequest *request;
+	MemoryContext oldcontext;
 
 	if (!process_shmem_requests_in_progress)
 		elog(FATAL, "cannot request additional LWLocks outside shmem_request_hook");
@@ -652,10 +653,17 @@ RequestNamedLWLockTranche(const char *tranche_name, int num_lwlocks)
 				 errdetail("No more than %d tranches may be registered.",
 						   MAX_USER_DEFINED_TRANCHES)));
 
-	request = MemoryContextAllocZero(PostmasterContext, sizeof(NamedLWLockTrancheRequest));
+	if (IsPostmasterEnvironment)
+		oldcontext = MemoryContextSwitchTo(PostmasterContext);
+	else
+		oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+
+	request = palloc0(sizeof(NamedLWLockTrancheRequest));
 	strlcpy(request->tranche_name, tranche_name, NAMEDATALEN);
 	request->num_lwlocks = num_lwlocks;
 	NamedLWLockTrancheRequests = lappend(NamedLWLockTrancheRequests, request);
+
+	MemoryContextSwitchTo(oldcontext);
 }
 
 /*