Re: 2.6.39-rc7-git11, x86/32, failed on ppp2897'th interface, PERCPU: allocation failed

[Eric Dumazet <eric.dumazet@gmail.com>]

Le jeudi 19 mai 2011 à 10:28 +0300, Denys Fedoryshchenko a écrit :
> On Thu, 19 May 2011 08:55:13 +0200, Eric Dumazet wrote:
> > Le jeudi 19 mai 2011 à 08:39 +0200, Eric Dumazet a écrit :
> >
> >> Its a known problem : When ipv6 is enabled, we allocate percpu 
> >> memory to
> >> hold per device snmp counters.
> >>
> >> make sure kernel idea of max possible cpus matches real number of 
> >> cpus.
> >>
> >> And yes, switching to 64bit kernel helps a lot.
> >>
> >>
> >
> > Looking at snmp6_alloc_dev(), we allocate three mib per device :
> >
> > ipstats_mib  (30 * sizeof(u64) * number_of_possible_cpus)
> > icmpv6_mib    (4 * sizeof(long) * number_of_possible_cpus)
> > icmpv6msg_mib  (26 * sizeof(long))
>  1920 +
>  256 +
>  208 = 2386 * 3000ppp's = 7152000, i think it is not that much at any 
>  case, if i am not wrong.
> 
>  But at any case i will try 64bit.

If you really want to stay 32bit, you might try to enlarge vmalloc aread
(128 Mbytes default) to get room for pcpu data :

grep pcpu /proc/vmallocinfo 


boot param : vmalloc=256M