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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: kernel BUG at mm/slqb.c:1411!
Cc: kosaki.motohiro@jp.fujitsu.com, Minchan Kim <minchan.kim@gmail.com>,
       linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>,
       Nick Piggin <npiggin@suse.de>
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Date: Thu, 14 May 2009 17:54:29 +0900 (JST)
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> On Wed, 2009-05-13 at 17:37 +0900, Minchan Kim wrote:
> > On Wed, 13 May 2009 16:42:37 +0900 (JST)
> > KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> > 
> > Hmm. I don't know slqb well.
> > So, It's just my guess. 
> > 
> > We surely increase l->nr_partial in  __slab_alloc_page.
> > In between l->nr_partial++ and call __cache_list_get_page, Who is decrease l->nr_partial again.
> > After all, __cache_list_get_page return NULL and hit the VM_BUG_ON.
> > 
> > Comment said :
> > 
> >         /* Protects nr_partial, nr_slabs, and partial */
> >   spinlock_t    page_lock;
> > 
> > As comment is right, We have to hold the l->page_lock ?
> 
> Makes sense. Nick? Motohiro-san, can you try this patch please?

This issue is very rarely. please give me one night.