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Subject: Re: [PATCHv11 2.6.36-rc2-tip 3/15]  3: uprobes: Slot allocation
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From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
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Date: Fri, 03 Sep 2010 19:25:18 +0200
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On Fri, 2010-09-03 at 22:10 +0530, Srikar Dronamraju wrote:
> > > +   vma = find_vma(mm, addr);
> > > +
> > > +   /* Don't expand vma on mremap(). */
> > > +   vma->vm_flags |= VM_DONTEXPAND | VM_DONTCOPY;
> > > +   area->vaddr = vma->vm_start;
> > 
> > Seems interesting,.. why not use install_special_mapping(), that's what
> > the VDSO uses.
> 
> Okay, I hadnt looked at install_special_mapping earlier so I will take a
> look and incorporate it. However I am not clear at this point what
> install_special_mapping is giving us here.  Also install_special_mapping
> is already defining its own vm_ops esp a close method thats doesnt seem
> to be doing anything. So at this point I am not clear how we are link
> the vm_ops, the close method and install_special_mapping.

What you're doing might well be the right thing, I was just wondering.

I think that, after thinking about it more, that the shmem file thing
you're doing has the added benefit that the things gets auto-magic
paging, which is a good thing.