From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
cc: jesper.pedersen@redhat.com, Thomas Munro <thomas.munro@enterprisedb.com>,
        Alvaro Herrera <alvherre@2ndquadrant.com>,
        Magnus Hagander <magnus@hagander.net>, Oskari Saarenmaa <os@ohmu.fi>,
        Pg Hackers <pgsql-hackers@postgresql.org>,
        Tobias Oberstein <tobias.oberstein@gmail.com>
Subject: Re: pread() and pwrite()
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Comments: In-reply-to Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
	message dated "Wed, 07 Nov 2018 07:55:17 -0500"
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Date: Wed, 07 Nov 2018 09:30:37 -0500
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Andrew Dunstan <andrew.dunstan@2ndquadrant.com> writes:
> On 11/7/18 7:26 AM, Jesper Pedersen wrote:
>> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dskink&dt=3D20=
18-11-07%2001%3A01%3A01

> And lousyjack, which uses a slightly different way of calling valgrind, =

> and thus got past initdb, found a bunch more:
> <https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dlousyjack&dt=3D=
2018-11-07%2001%3A33%3A01>

I'm confused by this.  Surely the pwrite-based code is writing exactly the
same data as before.  Do we have to conclude that valgrind is complaining
about passing uninitialized data to pwrite() when it did not complain
about exactly the same thing for write()?

[ looks ... ]  No, what we have to conclude is that the write-related
suppressions in src/tools/valgrind.supp need to be replaced or augmented
with pwrite-related ones.

			regards, tom lane