From b26d76f643277973f90a62f18de30e00edd65378 Mon Sep 17 00:00:00 2001 From: Nathan Bossart Date: Wed, 12 Nov 2025 14:30:11 -0600 Subject: [PATCH] Teach DSM registry to ERROR if attaching to an uninitialized entry. If DSM entry initialization fails, backends could try to use an uninitialized DSM segment, DSA, or dshash table (since the entry is still added to the registry). To fix, keep track of whether initialization completed, and ERROR if a backend tries to attach to an uninitialized entry. We could instead retry initialization as needed, but that seemed complicated, error prone, and unlikely to help most cases. Furthermore, such problems probably indicate a coding error. Reported-by: Alexander Lakhin Reviewed-by: Sami Imseih Discussion: https://postgr.es/m/dd36d384-55df-4fc2-825c-5bc56c950fa9%40gmail.com Backpatch-through: 17 --- src/backend/storage/ipc/dsm_registry.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/src/backend/storage/ipc/dsm_registry.c b/src/backend/storage/ipc/dsm_registry.c index 1d4fd31ffed..8511b7afc7b 100644 --- a/src/backend/storage/ipc/dsm_registry.c +++ b/src/backend/storage/ipc/dsm_registry.c @@ -45,6 +45,7 @@ typedef struct DSMRegistryEntry char name[64]; dsm_handle handle; size_t size; + bool initialized; } DSMRegistryEntry; static const dshash_parameters dsh_params = { @@ -158,8 +159,12 @@ GetNamedDSMSegment(const char *name, size_t size, entry = dshash_find_or_insert(dsm_registry_table, name, found); if (!(*found)) { + dsm_segment *seg; + + entry->initialized = false; + /* Initialize the segment. */ - dsm_segment *seg = dsm_create(size, 0); + seg = dsm_create(size, 0); dsm_pin_segment(seg); dsm_pin_mapping(seg); @@ -169,13 +174,17 @@ GetNamedDSMSegment(const char *name, size_t size, if (init_callback) (*init_callback) (ret); + + entry->initialized = true; } + else if (!entry->initialized) + ereport(ERROR, + (errmsg("requested DSM segment \"%s\" failed initialization", + name))); else if (entry->size != size) - { ereport(ERROR, - (errmsg("requested DSM segment size does not match size of " - "existing segment"))); - } + (errmsg("requested DSM segment \"%s\" does not match size of existing entry", + name))); else { dsm_segment *seg = dsm_find_mapping(entry->handle); -- 2.39.5