Re: /proc/self/oom_adj is deprecated in newer Linux kernels

On 2014-06-10 11:14:43 -0400, Tom Lane wrote:
> Sure, but what's that have to do with this? Any Red Hat or PGDG RPM will
> come with this code already enabled in the build, so there is no need for
> anyone to have a GUC to play around with the behavior.

That's imo a fair point. Unless I misunderstand things Gurjeet picked
the topic up again because he wants to increase the priority of the
children. Is that correct Gurjeet?

I do think a GUC might be a nicer interface for this than a
#define. Possibly even with a absolute reset value for the children. But
only because there's no way, afaics, to explicitly reset to the default
value.

> >> I remain of the opinion that allowing nonprivileged people to decide
> >> whether that code is active or not is unsafe from a system level.
>
> > On what factual basis?
>
> Because it would convert the intended behavior (postmaster and only
> postmaster is exempt from OOM kill) into a situation where possibly
> all of the database processes are exempt from OOM kill, at the whim
> of somebody who should not have the privilege to decide that.

Meh^3. By that argument we need to forbid superusers to create any form
of untrusted functions. Forbid anything that does malloc(), system(),
fork(), whatever from a user's influence.
Superusers can execute code in the postmaster using
shared_preload_libraries. Feigning that that's not possible isn't buying
us anything.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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