From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
cc: pgsql-hackers@postgreSQL.org
Subject: Re: Back-patch use of unnamed POSIX semaphores for Linux?
In-reply-to: <722c489e-810a-be9c-f005-3b6bdcb4c59f@2ndquadrant.com>
References: <32387.1481079186@sss.pgh.pa.us>
 <722c489e-810a-be9c-f005-3b6bdcb4c59f@2ndquadrant.com>
Comments: In-reply-to Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
	message dated "Wed, 07 Dec 2016 08:54:17 -0500"
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Date: Wed, 07 Dec 2016 09:38:10 -0500
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Peter Eisentraut <peter.eisentraut@2ndquadrant.com> writes:
> On 12/6/16 9:53 PM, Tom Lane wrote:
>> I think we should give serious consideration to back-patching commit
>> ecb0d20a9, which changed the default semaphore type to unnamed-POSIX
>> on Linux.

> Even with that change, dynamic shared memory is still vulnerable to be
> removed.

Really?  I thought we concluded that it is safe because it is detectably
attached to running processes.  The trouble with SysV semaphores is that
they lack any such attachment, so systemd is left to guess whether they
are still in use.

			regards, tom lane


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