v3-0001-Allow-palloc_extended-NO_OOM-in-critical-sections.patch

From d678e740c61ed5408ad254d2ca5f8e2fff7d2cd1 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 1 Nov 2022 23:29:38 +1300
Subject: [PATCH v3 1/6] Allow palloc_extended(NO_OOM) in critical sections.

Commit 4a170ee9e0e banned palloc() and similar in critical sections, because an
allocation failure would produce a panic.  Make an exception for allocation
with NULL on failure, for code that has a backup plan.

Discussion: https://postgr.es/m/CA%2BhUKGJHudZMG_vh6GiPB61pE%2BGgiBk5jxzd7inijqx5nEZLCw%40mail.gmail.com
---
 src/backend/utils/mmgr/mcxt.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/backend/utils/mmgr/mcxt.c b/src/backend/utils/mmgr/mcxt.c
index 0b00802df7..eb18b89368 100644
--- a/src/backend/utils/mmgr/mcxt.c
+++ b/src/backend/utils/mmgr/mcxt.c
@@ -1123,7 +1123,8 @@ MemoryContextAllocExtended(MemoryContext context, Size size, int flags)
 	void	   *ret;
 
 	Assert(MemoryContextIsValid(context));
-	AssertNotInCriticalSection(context);
+	if ((flags & MCXT_ALLOC_NO_OOM) == 0)
+		AssertNotInCriticalSection(context);
 
 	if (!((flags & MCXT_ALLOC_HUGE) != 0 ? AllocHugeSizeIsValid(size) :
 		  AllocSizeIsValid(size)))
@@ -1278,7 +1279,8 @@ palloc_extended(Size size, int flags)
 	MemoryContext context = CurrentMemoryContext;
 
 	Assert(MemoryContextIsValid(context));
-	AssertNotInCriticalSection(context);
+	if ((flags & MCXT_ALLOC_NO_OOM) == 0)
+		AssertNotInCriticalSection(context);
 
 	if (!((flags & MCXT_ALLOC_HUGE) != 0 ? AllocHugeSizeIsValid(size) :
 		  AllocSizeIsValid(size)))
@@ -1509,7 +1511,8 @@ repalloc_extended(void *pointer, Size size, int flags)
 		  AllocSizeIsValid(size)))
 		elog(ERROR, "invalid memory alloc request size %zu", size);
 
-	AssertNotInCriticalSection(context);
+	if ((flags & MCXT_ALLOC_NO_OOM) == 0)
+		AssertNotInCriticalSection(context);
 
 	/* isReset must be false already */
 	Assert(!context->isReset);
-- 
2.39.2