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Date: Tue, 6 May 2008 20:37:50 -0700
From: "Paul Menage" <menage@google.com>
To: "KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: on CONFIG_MM_OWNER=y, kernel panic is possible.
Cc: balbir@linux.vnet.ibm.com, "Lee Schermerhorn" <Lee.Schermerhorn@hp.com>,
       "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>,
       LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>,
       "Andrew Morton" <akpm@linux-foundation.org>
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On Mon, May 5, 2008 at 11:43 PM, KOSAKI Motohiro
<kosaki.motohiro@jp.fujitsu.com> wrote:
> > >  #ifdef CONFIG_MM_OWNER
>  > > -       struct task_struct *owner;      /* The thread group leader that */
>  > > -                                       /* owns the mm_struct.          */
>  > > +       struct task_struct *owner;      /* point to one of task that owns the mm_struct. */
>  > >  #endif
>  > >
>  > >  #ifdef CONFIG_PROC_FS
>  >
>  > How about just, the task that owns the mm_struct? One of, implies multiple owners.
>
>  Ah, below is better?
>
>  /* point to any one of task that related the mm_struct. */

I'd word it as

/*
 * "owner" points to a task that is regarded as the canonical
 * user/owner of this mm. All of the following must be true in
 * order for it to be changed:
 *
 * current == mm->owner
 * current->mm != mm
 * new_owner->mm == mm
 * new_owner->alloc_lock is held
 */

Paul