From: Andi Kleen <ak@suse.de>
To: Eric Dumazet <dada1@cosmosbay.com>
Subject: Re: [RFC] NUMA futex hashing
Date: Tue, 8 Aug 2006 14:47:42 +0200
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Cc: Ravikiran G Thirumalai <kiran@scalex86.org>,
       "Shai Fultheim (Shai@scalex86.org)" <shai@scalex86.org>,
       pravin b shelar <pravin.shelar@calsoftinc.com>,
       linux-kernel@vger.kernel.org
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On Tuesday 08 August 2006 14:29, Eric Dumazet wrote:
> On Tuesday 08 August 2006 12:36, Andi Kleen wrote:
> > > We may have special case for PRIVATE futexes (they dont need to be
> > > chained in a global table, but a process private table)
> >
> > What do you mean with PRIVATE futex?
> >
> > Even if the futex mapping is only visible by a single MM mmap_sem is still
> > needed to protect against other threads doing mmap.
> 
> Hum... I would call that a user error.
> 
> If a thread is munmap()ing the vma that contains active futexes, result is 
> undefined.

We can't allow anything that could crash the kernel, corrupt a kernel,
data structure, allow writing to freed memory etc.  No matter how
defined it is or not. Working with a vma that doesn't have 
an existence guarantee would be just that.

-Andi
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