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Presently, relation_needs_vacanalyze() unconditionally frees the pgstat entry returned by pgstat_fetch_stat_tabentry_ext(). This behavior was first added by commit02502c1bcato avoid memory leakage in autovacuum. While this is fine for autovacuum since it forces stats_fetch_consistency to "none", it is not okay for other callers that use "cache" or "snapshot". This manifests as a double-free when pg_stat_autovacuum_scores is called multiple times in the same transaction. To fix, add a "bool *may_free" parameter to pgstat_fetch_stat_tabentry_ext() that returns whether it is safe for the caller to explicitly pfree() the result. If a caller would rather leave it to the memory context machinery to free the result, it can pass NULL as the "may_free" argument (or just ignore its value). Oversight in commit87f61f0c82. Reported-by: Tender Wang <tndrwang@gmail.com> Reported-by: Alexander Lakhin <exclusion@gmail.com> Suggested-by: Andres Freund <andres@anarazel.de> Suggested-by: Tom Lane <tgl@sss.pgh.pa.us> Author: Sami Imseih <samimseih@gmail.com> Discussion: https://postgr.es/m/CAHewXNkJKdwb3D5OnksrdOqzqUnXUEMpDam1TPW0vfUkW%3D7jUw%40mail.gmail.com Discussion: https://postgr.es/m/5684f479-858e-4c5d-b8f5-bcf05de1f909%40gmail.com