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SubjectRe: [PATCH next/mmotm] slub: partly fix freeze in __slab_free
On 7/11/11 10:39 PM, Eric Dumazet wrote:
> Le lundi 11 juillet 2011 à 11:58 -0700, Hugh Dickins a écrit :
>> My load tests on PowerPC freeze within minutes in __slab_free().
>> I happened to try PPC first, didn't try without this fix on x86.
>>
>> It looks as if the author was interrupted while devising the new
>> cmpxchg_double_slab() version of __slab_free(): its decision to
>> spin_lock_irqsave() depends on several uninitialized fields,
>> and fixing that (by copying page to new) mostly fixes it.
>>
>> But I didn't think about it very much, and this may well not be what
>> the author intends; and I have seen a couple of much rarer freezes
>> in __slab_free() on PPC (not yet on x86) even after applying this.
>>
>> Signed-off-by: Hugh Dickins<hughd@google.com>
>> ---
>> mm/slub.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> --- mmotm/mm/slub.c 2011-07-08 18:59:44.135443127 -0700
>> +++ linux/mm/slub.c 2011-07-10 05:07:08.000000000 -0700
>> @@ -2217,6 +2217,7 @@ static void __slab_free(struct kmem_cach
>> return;
>>
>> do {
>> + new = *page;
>> prior = page->freelist;
>> counters = page->counters;
>> set_freepointer(s, object, prior);
>> --
> I suspect you hit the bug on 32bit arch ?
>
> What about following patch instead ?
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 3d76a43..1351d28 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -62,7 +62,7 @@ struct page {
> struct { /* SLUB cmpxchg_double area */
> void *freelist;
> union {
> - unsigned long counters;
> + u64 counters;
> struct {
> unsigned inuse:16;
> unsigned objects:15;
>

Christoph?
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