Re: [Bug #12409] NULL pointer dereference at get_stats()

Tetsuo Handa
2009-01-24T00:39:03Z

Hello.

Frederik Deweerdt wrote:
> On Mon, Jan 19, 2009 at 10:45:43PM +0100, Rafael J. Wysocki wrote:
> > This message has been generated automatically as a part of a report
> > of regressions introduced between 2.6.27 and 2.6.28.
> >
> > The following bug entry is on the current list of known regressions
> > introduced between 2.6.27 and 2.6.28. Please verify if it still should
> > be listed and let me know (either way).
> >
> >
> > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=12409
> > Subject : NULL pointer dereference at get_stats()
> > Submitter : Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
> > Date : 2008-12-30 12:53 (21 days old)
> > References : http://marc.info/?l=linux-kernel&m=123064167008695&w=4
> > Handled-By : Frederik Deweerdt <frederik.deweerdt@xprog.eu>
> >
> >
> Hello Rafael,
>
> Not sure what the status should be for that one, it sure seems vmware
> related, and I don't have one handy.
>
> Regards,
> Frederik
>
The latest post regarding this problem starts at http://lkml.org/lkml/2009/1/4/349 .
It's not a VMware related problem.

A patch at http://lkml.org/lkml/2009/1/5/557 reported that "nolapic" option
doesn't prevent for_each_possible_cpu() from reaching CPU1, and per-CPU pointer
for CPU1 is NULL.

--- First call of for_each_possible_cpu() ---
Entering get_stats()
CPU=0
Leaving get_stats()

--- Second call of for_each_possible_cpu() ---
Entering get_stats()
CPU=0
CPU=1
lb_stats == NULL for CPU 1
Leaving get_stats()

Regards.