Re: [PATCH] IPC: account for kmem usage on mqueue and msg

[Aristeu Rozanski <arozansk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

Hi Michal,
On Tue, Oct 18, 2016 at 08:26:19PM +0200, Michal Hocko wrote:
> I guess this was because ipv msgqueue shouldn't allow for memory
> consumption runaways. The number of message queues and messages pending
> in them is bounded and not a large amount of memory AFAIR. Anyway I do
> not see anything unreasonable about accounting the memory to the caller.
> 
> Have you noticed this by a code inspection or you have a real world
> usecase where the missing accounting caused some problems? This would be
> a useful information for the changelog.

Stefan noticed this and filled an internal BZ and I saw it with a
test program while comparing with our 3.10 kernel. We haven't hit this
issue in production (AFAIK) but it's a concern while using containers.

Each message is up to 16MB and you can't get too many messages queued.
While it's something that won't allow a container to eat a large portion
of memory, it's significant enough to be accounted for.

-- 
Aristeu