lkml.org 
[lkml]   [2009]   [Sep]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 1/3] slqb: Do not use DEFINE_PER_CPU for per-node data
    From
    Date
    Hi Tejun,

    On Mon, 2009-09-21 at 00:55 +0900, Tejun Heo wrote:
    > Pekka Enberg wrote:
    > > Tejun Heo wrote:
    > >> Pekka Enberg wrote:
    > >>> On Fri, Sep 18, 2009 at 10:34 PM, Mel Gorman <mel@csn.ul.ie> wrote:
    > >>>> SLQB used a seemingly nice hack to allocate per-node data for the
    > >>>> statically
    > >>>> initialised caches. Unfortunately, due to some unknown per-cpu
    > >>>> optimisation, these regions are being reused by something else as the
    > >>>> per-node data is getting randomly scrambled. This patch fixes the
    > >>>> problem but it's not fully understood *why* it fixes the problem at the
    > >>>> moment.
    > >>> Ouch, that sounds bad. I guess it's architecture specific bug as x86
    > >>> works ok? Lets CC Tejun.
    > >>
    > >> Is the corruption being seen on ppc or s390?
    > >
    > > On ppc.
    >
    > Can you please post full dmesg showing the corruption? Also, if you
    > apply the attached patch, does the added BUG_ON() trigger?

    I don't have the affected machines, Sachin and Mel do.

    Pekka

    > diff --git a/include/linux/percpu.h b/include/linux/percpu.h
    > index 878836c..fb690d2 100644
    > --- a/include/linux/percpu.h
    > +++ b/include/linux/percpu.h
    > @@ -127,7 +127,7 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size,
    > * dynamically allocated. Non-atomic access to the current CPU's
    > * version should probably be combined with get_cpu()/put_cpu().
    > */
    > -#define per_cpu_ptr(ptr, cpu) SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))
    > +#define per_cpu_ptr(ptr, cpu) ({ BUG_ON(!(ptr)); SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))); })
    >
    > extern void *__alloc_reserved_percpu(size_t size, size_t align);



    \
     
     \ /
      Last update: 2009-09-21 08:27    [W:0.039 / U:0.592 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site