Horton

Re: PANIC: wrong buffer passed to visibilitymap_clear

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-04-13T01:54:44Z
Lists: pgsql-hackers 
On Mon, Apr 12, 2021 at 6:33 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Thanks for looking it over.  Do you have an opinion on whether or not
> to back-patch?  As far as we know, these bugs aren't exposed in the
> back branches for lack of code that would set the all-visible flag
> without superexclusive lock.  But I'd still say that heap_update
> is failing to honor its API contract in these edge cases, and that
> seems like something that could bite us after future back-patches.

If we assume that a scenario like the one we've been debugging can
never happen in the backbranches, then we must also assume that your
fix has negligible risk in the backbranches, because of how it is
structured. And so I agree -- I lean towards backpatching.

-- 
Peter Geoghegan

Commits

  1. Avoid improbable PANIC during heap_update.

  2. Refactor lazy_scan_heap() loop.