On Thu, Apr 17, 2014 at 6:41 PM, Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> wrote: > 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. You don't understand it, because I was being dense :-}. I misunderstood your patch. I think I was thrown by this line in the commit message: The patch disables both limits by setting the limits to ULONG_MAX. Of course, you patch doesn't *disable* the limits, it simply sets the defaults to the maximum. >>> 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? Well, actually, BOTH patches change the API, because they both affect SHMALL/SHMMAX. Cheers, Michael > I'll try to make a v2 (with your update to the uapi header file) tomorrow. > > -- > Manfred -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>