linux-kernel - Re: [shm][hugetlb] Fix get_policy for stacked shared memory files

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Message-Id: <200706121220.11332.ak@suse.de>
Date:	Tue, 12 Jun 2007 12:20:11 +0200
From:	Andi Kleen <ak@...e.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Adam Litke <agl@...ibm.com>, dean gaudet <dean@...tic.org>,
	William Lee Irwin III <wli@...omorphy.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org, clameter@....com
Subject: Re: [shm][hugetlb] Fix get_policy for stacked shared memory files


> Can we just double-check the refcounting please?
> 
> > index 4fefbad..8d2672d 100644
> > --- a/ipc/shm.c
> > +++ b/ipc/shm.c
> > @@ -254,8 +254,10 @@ struct mempolicy *shm_get_policy(struct vm_area_struct *vma, unsigned long addr)
> >  
> >  	if (sfd->vm_ops->get_policy)
> >  		pol = sfd->vm_ops->get_policy(vma, addr);
> 
> afacit this takes a ref on the underlying policy
> 
> > -	else
> > +	else if (vma->vm_policy)
> >  		pol = vma->vm_policy;
> > +	else
> > +		pol = current->mempolicy;
> 
> but these two do not.
> 
> >  	return pol;
> >  }
> >  #endif
> 
> Is is all correct?

No it looks broken.

-Andi
-
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