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commit    181361a0c2fec635de10e101f683da9bddbb8178
Author:   Thomas Munro <tmunro@postgresql.org>
Date:     Mon Oct 25 23:54:55 2021 +0000

    Reject huge_pages=on if shared_memory_type=sysv.
    
    It doesn't work (it could, but hasn't been implemented).
    Back-patch to 12, where shared_memory_type arrived.
    
    Reported-by: Alexander Lakhin <exclusion@gmail.com>
    Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
    Discussion: https://postgr.es/m/163271880203.22789.1125998876173795966@wrigleys.postgresql.org


 doc/src/sgml/config.sgml      | 4 +++-
 src/backend/port/sysv_shmem.c | 6 ++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 0c3193bfebb..b5d06b49e29 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1664,7 +1664,9 @@ include_dir 'conf.d'
        <para>
         At present, this setting is supported only on Linux and Windows. The
         setting is ignored on other systems when set to
-        <literal>try</literal>.
+        <literal>try</literal>.  On Linux, it is only supported when
+        <varname>shared_memory_type</varname> is set to <literal>mmap</literal>
+        (the default).
        </para>
 
        <para>
diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c
index 9de96edf6ad..35cce89e9c9 100644
--- a/src/backend/port/sysv_shmem.c
+++ b/src/backend/port/sysv_shmem.c
@@ -686,6 +686,12 @@ PGSharedMemoryCreate(Size size,
 				 errmsg("huge pages not supported on this platform")));
 #endif
 
+	/* For now, we don't support huge pages in SysV memory */
+	if (huge_pages == HUGE_PAGES_ON && shared_memory_type != SHMEM_TYPE_MMAP)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("huge pages not supported with the current shared_memory_type setting")));
+
 	/* Room for a header? */
 	Assert(size > MAXALIGN(sizeof(PGShmemHeader)));
 


[parent: a5b9a0000e14]