From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Robert Haas <robertmhaas@gmail.com>,
        Thomas Munro <thomas.munro@enterprisedb.com>,
        "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: pgsql: Add parallel-aware hash joins.
In-reply-to: <20180104200647.wna6yoin7nav5qqo@alap3.anarazel.de>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Thu, 04 Jan 2018 12:06:47 -0800"
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Date: Thu, 04 Jan 2018 15:16:15 -0500
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Andres Freund <andres@anarazel.de> writes:
> On 2018-01-04 11:20:33 -0800, Andres Freund wrote:
>> Some packages on skink have been upgraded. It appears that there either
>> was a libc or valgrind change that made valgrind not recognize that a
>> pointer of 0 might not point anywhere :(

> ==5718== Invalid write of size 8
> ==5718==    at 0x40E3DD: ExecInterpExpr (execExprInterp.c:1117)
> ==5718==    by 0x40F5E9: ExecInterpExprStillValid (execExprInterp.c:1788)
> ==5718==    by 0xE6B0409: ExecEvalExpr (executor.h:282)

Are those line numbers supposed to match current HEAD?  1117 does not
contain any write AFAICS:

	if (!op->d.iocoerce.finfo_in->fn_strict || str != NULL)

> ==5718== Process terminating with default action of signal 11 (SIGSEGV)
> ==5718==  Access not within mapped region at address 0x20
> ==5718==    at 0x40E3DD: ExecInterpExpr (execExprInterp.c:1117)
> ==5718==    by 0x40F5E9: ExecInterpExprStillValid (execExprInterp.c:1788)

This would be consistent with op->d.iocoerce.finfo_in being NULL, I think,
but there is no way that execExpr.c could have created an EEOP_IOCOERCE
step without filling in the finfo_in pointer.

I think the correct conclusion is that this version of valgrind is
buggy as hell.  I wouldn't clutter our code with suppressions trying
to make it sort-of work.

			regards, tom lane