linux-kernel - Re: [PATCH RFC 0/2] add nproc cgroup subsystem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150227193539.GO3964@htj.duckdns.org>
Date:	Fri, 27 Feb 2015 14:35:39 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Austin S Hemmelgarn <ahferroin7@...il.com>
Cc:	Aleksa Sarai <cyphar@...har.com>, lizefan@...wei.com,
	mingo@...hat.com, peterz@...radead.org, richard@....at,
	fweisbec@...il.com, linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org
Subject: Re: [PATCH RFC 0/2] add nproc cgroup subsystem

Hello, Austin.

On Fri, Feb 27, 2015 at 01:49:53PM -0500, Austin S Hemmelgarn wrote:
> As far as being trivial to achieve, I'm assuming you are referring to rlimit
> and PAM's limits module, both of which have their own issues. Using
> pam_limits.so to limit processes isn't trivial because it requires calling
> through PAM to begin with, which almost no software that isn't login related
> does, and rlimits are tricky to set up properly with the granularity that
> having a cgroup would provide.
...
> PID's are a fundamental resource, you run out and it's an only marginally
> better situation than OOM, namely, if you don't already have a shell open
> which has kill builtin (because you can't fork), or have some other reliable
> way to terminate processes without forking, you are stuck either waiting for
> the problem to resolve itself, or have to reset the system.

Right, this is an a lot more valid argument.  Currently, we're capping
max pid at 4M which translates to some tens of gigs of memory which
isn't a crazy amount on modern machines.  The hard(er) barrier would
be around 2^30 (2^29 from futex side, apparently) which would also be
reacheable on configurations w/ terabytes of memory.

I'll think more about it and get back.

Thanks a lot.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/