Messages in this thread | | | Date | Sun, 04 May 2014 13:17:40 +0200 | From | Manfred Spraul <> | Subject | Re: [PATCH] IPC initialize shmmax and shmall from the current value not the default |
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Hi Marian,
Note: The limits will soon be increased to (nearly) ULONG_MAX. I.e.: If you propose the patch because you are running into issues with a too small SEMMAX after an unshare(CLONE_NEWIPC), then this will be fixed soon.
On 05/04/2014 01:53 AM, Davidlohr Bueso wrote: > On Sun, 2014-05-04 at 01:48 +0300, Marian Marinov wrote: >> When we are creating new IPC namespace that should be cloned from the current namespace it is a good idea to copy the >> values of the current shmmax and shmall to the new namespace. The idea sounds reasonable: If an admin has reduced the limits, then the reduction should also apply after a unshare(CLONE_NEWIPC).
But: Your patch doesn't use the current shmmax, it uses the shmmax from init_ipc_ns. Would it be possible to use the current values?
> Why is this a good idea? > > This would break userspace that relies on the current behavior. > Furthermore we've recently changed the default value of both these > limits to be as large as you can get, thus deprecating them. I don't > like the idea of this being replaced by namespaces. Davidlohr: We are not deprecating them, we make the default huge. The limits should stay as usable as they were.
With regards to breaking user space, I must think about it a bit more. Right now, each new namespace starts with SEMMAX=32MB, i.e. an often unusable default.
-- Manfred
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