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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: David Rientjes <rientjes@google.com>
Subject: Re: [PATCH 13/14] mm: mempolicy: Check return code of check_range
Cc: kosaki.motohiro@jp.fujitsu.com, Kulikov Vasiliy <segooon@gmail.com>,
        kernel-janitors@vger.kernel.org,
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> On Mon, 6 Sep 2010, KOSAKI Motohiro wrote:
> 
> > > From: Vasiliy Kulikov <segooon@gmail.com>
> > > 
> > > Function check_range may return ERR_PTR(...). Check for it.
> > 
> > When happen this issue?
> > 
> > afaik, check_range return error when following condition.
> >  1) mm->mmap->vm_start argument is incorrect
> >  2) don't have neigher MPOL_MF_STATS, MPOL_MF_MOVE and MPOL_MF_MOVE_ALL
> > 
> > I think both case is not happen in real. Am I overlooking anything?
> > 
> 
> There's no reason not to check the return value of a function when the 
> implementation of either could change at any time.  migrate_to_node() is 
> certainly not in any fastpath where we can't sacrifice a branch for more 
> robust code.

I was not against this change. I was asking patch effectness.