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Subject: Re: mprotect pgprot handling weirdness
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: linux-mm@kvack.org
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Date: Tue, 06 Apr 2010 15:32:06 +1000
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On Tue, 2010-04-06 at 15:09 +1000, Benjamin Herrenschmidt wrote:
> Hi folks !
> 
> While looking at untangling a bit some of the mess with vm_flags and
> pgprot (*), I notices a few things I can't quite explain... they may ..
> or may not be bugs, but I though it was worth mentioning:

 And another one:

- vma_wants_writenotify():

	/* The open routine did something to the protections already? */
	if (pgprot_val(vma->vm_page_prot) !=
	    pgprot_val(vm_get_page_prot(vm_flags)))
		return 0;

That's going to blow if any -other- prot bit is used here.

Cheers,
Ben.