linux-kernel - Re: [PATCH] ipc,mqueue: remove limits for the amount of system-wide queues

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Date:	Tue, 11 Feb 2014 13:14:07 -0500
From:	Doug Ledford <dledford@...hat.com>
To:	Davidlohr Bueso <davidlohr@...com>, m@...odev.com,
	stable@...r.kernel.org, akpm@...ux-foundation.org
CC:	linux-kernel@...r.kernel.org,
	Manfred Spraul <manfred@...orfullife.com>
Subject: Re: [PATCH] ipc,mqueue: remove limits for the amount of system-wide
 queues

On 2/9/2014 4:06 PM, Davidlohr Bueso wrote:
> From: Davidlohr Bueso <davidlohr@...com>
> 
> Commit 93e6f119 (ipc/mqueue: cleanup definition names and locations) added
> global hardcoded limits to the amount of message queues that can be created.
> While these limits are per-namespace, reality is that it ends up breaking
> userspace applications. Historically users have, at least in theory, been able
> to create up to INT_MAX queues, and limiting it to just 1024 is way too low
> and dramatic for some workloads and use cases. For instance, Madars reports:
> 
> "This update imposes bad limits on our multi-process application. As our
> app uses approaches that each process opens its own set of queues (usually
> something about 3-5 queues per process). In some scenarios we might run up
> to 3000 processes or more (which of-course for linux is not a problem).
> Thus we might need up to 9000 queues or more. All processes run under one
> user."
> 
> Other affected users can be found in launchpad bug #1155695:
> https://bugs.launchpad.net/ubuntu/+source/manpages/+bug/1155695
> 
> Instead of increasing this limit, revert it entirely and fallback to the
> original way of dealing queue limits -- where once a user's resource limit
> is reached, and all memory is used, new queues cannot be created.
> 
> Reported-by: m@...odev.com
> Cc: Doug Ledford <dledford@...hat.com>

Acked-by: Doug Ledford <dledford@...hat.com>

> Cc: Manfred Spraul <manfred@...orfullife.com>
> Cc: stable@...r.kernel.org # v3.5+
> Signed-off-by: Davidlohr Bueso <davidlohr@...com>
> ---
>  include/linux/ipc_namespace.h |  2 --
>  ipc/mq_sysctl.c               | 18 ++++++++++++------
>  ipc/mqueue.c                  |  6 +++---
>  3 files changed, 15 insertions(+), 11 deletions(-)



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