Re: [RFC 0/5] percpu: Optimize percpu accesses

Ingo Molnar
2008-07-01T15:03:42Z

* Ingo Molnar <mingo@elte.hu> wrote:

> > This patchset provides the following:
> >
> > * Cleanup: Fix early references to cpumask_of_cpu(0)
> > * Generic: Percpu infrastructure to rebase the per cpu area to zero
> > * x86_64: Fold pda into per cpu area
> > * x86_64: Rebase per cpu variables to zero
>
> thanks Mike - i've started testing it in -tip. One small merge fallout
> fix is below. (it's for the new generic-ipi topic that was not in
> tip/master yet when you merged percpu-zerobased to it)

ok, -tip testing found an early boot crash caused by your patchset, on
64-bit x86:

[ 0.396000] calling net_ns_init+0x0/0x143
[ 0.400000] net_namespace: 944 bytes
[ 0.403578] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[ 0.404000] IP: [<ffffffff80e05b0e>] net_ns_init+0x9f/0x143
[ 0.404000] PGD 0
[ 0.404000] Oops: 0000 [1] SMP
[ 0.404000] CPU 0
[...]

full bootlog and config can be found at:

http://redhat.com/~mingo/misc/crashlog-Tue_Jul__1_16_48_45_CEST_2008.bad
http://redhat.com/~mingo/misc/config-Tue_Jul__1_16_48_45_CEST_2008.bad

(another 64-bit testbox crashed as well, so this should be readily
reproducible.)

i've pushed this tree out to tip/tmp.core/percpu-zerobased.Jul__1_16_48
topic branch, that is the 2.6.26-rc8-tip-00250-g90874b0 kernel you can
see in the crashlog.

Ingo