Re: [PATCH] slub: assign refcount for kmalloc_caches

[Paul Hargrove <phhargrove@lbl.gov>]

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I just had a look at patch-3.7.2-rc1, and this change doesn't appear to
have made it in yet.
Am I missing something?

-Paul


On Tue, Dec 25, 2012 at 7:30 AM, JoonSoo Kim <js1304@gmail.com> wrote:

> 2012/12/26 Joonsoo Kim <js1304@gmail.com>:
> > commit cce89f4f6911286500cf7be0363f46c9b0a12ce0('Move kmem_cache
> > refcounting to common code') moves some refcount manipulation code to
> > common code. Unfortunately, it also removed refcount assignment for
> > kmalloc_caches. So, kmalloc_caches's refcount is initially 0.
> > This makes errornous situation.
> >
> > Paul Hargrove report that when he create a 8-byte kmem_cache and
> > destory it, he encounter below message.
> > 'Objects remaining in kmalloc-8 on kmem_cache_close()'
> >
> > 8-byte kmem_cache merge with 8-byte kmalloc cache and refcount is
> > increased by one. So, resulting refcount is 1. When destory it, it hit
> > refcount = 0, then kmem_cache_close() is executed and error message is
> > printed.
> >
> > This patch assign initial refcount 1 to kmalloc_caches, so fix this
> > errornous situtation.
> >
> > Cc: <stable@vger.kernel.org> # v3.7
> > Cc: Christoph Lameter <cl@linux.com>
> > Reported-by: Paul Hargrove <phhargrove@lbl.gov>
> > Signed-off-by: Joonsoo Kim <js1304@gmail.com>
> >
> > diff --git a/mm/slub.c b/mm/slub.c
> > index a0d6984..321afab 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -3279,6 +3279,7 @@ static struct kmem_cache *__init
> create_kmalloc_cache(const char *name,
> >         if (kmem_cache_open(s, flags))
> >                 goto panic;
> >
> > +       s->refcount = 1;
> >         list_add(&s->list, &slab_caches);
> >         return s;
> >
> > --
> > 1.7.9.5
> >
>
> I missed some explanation.
> In v3.8-rc1, this problem is already solved.
> See create_kmalloc_cache() in mm/slab_common.c.
> So this patch is just for v3.7 stable.
>



-- 
Paul H. Hargrove                          PHHargrove@lbl.gov
Future Technologies Group
Computer and Data Sciences Department     Tel: +1-510-495-2352
Lawrence Berkeley National Laboratory     Fax: +1-510-486-6900

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