Messages in this thread Patch in this message | | | Date | Mon, 21 Sep 2009 00:55:56 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH 1/3] slqb: Do not use DEFINE_PER_CPU for per-node data |
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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?
Thanks.
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);
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