Re: [PATCH] ipc,shm: increase default size for shmmax

[Manfred Spraul]

On 04/17/2014 12:41 PM, Michael Kerrisk wrote:
> On Thu, Apr 17, 2014 at 12:46 AM, Andrew Morton
> <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> > On Sun, 13 Apr 2014 20:05:34 +0200 Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> wrote:
> >
> > > Hi Andrew,
> > >
> > > On 04/02/2014 12:08 AM, Andrew Morton wrote:
> > > > Well, I'm assuming 64GB==infinity. It *was* infinity in the RHEL5
> > > > timeframe, but infinity has since become larger so pickanumber.
> > > I think infinity is the right solution:
> > > The only common case where infinity is wrong would be Android - and
> > > Android disables sysv shm entirely.
> > >
> > > There are two patches:
> > > http://marc.info/?l=linux-kernel&m=139730332306185&q=raw
> > > http://marc.info/?l=linux-kernel&m=139727299800644&q=raw
> > >
> > > Could you apply one of them?
> > > I wrote the first one, thus I'm biased which one is better.
> > I like your patch because applying it might encourage you to send more
> > kernel patches - I miss the old days ;)
> >
> > But I do worry about disrupting existing systems so I like Davidlohr's
> > idea of making the change a no-op for people who are currently
> > explicitly setting shmmax and shmall.
> Agreed. It's hard to imagine situations where people might care
> nowadays, but there's no limits to people's insane inventiveness. Some
> people really might want to set an upper limit.
I don't understand that: neither patch has any impact after an explicit 
sysctl that overwrites shmmax.

> > In an ideal world, system administrators would review this change,
> And in the ideal world, patches such as this would CC
> linux-api@xxxxxxxxxxxxxxx, as described in
> Documentation/SubmitChecklist, so that users who care about getting
> advance warning on API changes could be alerted and might even review
> and comment...
Good point.
Davidlohr: Your patch has an impact on shmctl(,IPC_INFO,).
Could you add that for v3?

I'll try to make a v2 (with your update to the uapi header file) tomorrow.

--
    Manfred
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