linux-kernel - Re: [PATCH v6 02/10] x86, mpx: add MPX specific mmap interface

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Message-ID: <53A88DE4.8050107@intel.com>
Date:	Mon, 23 Jun 2014 13:28:20 -0700
From:	Dave Hansen <dave.hansen@...el.com>
To:	Andy Lutomirski <luto@...capital.net>
CC:	Qiaowei Ren <qiaowei.ren@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux MM <linux-mm@...ck.org>
Subject: Re: [PATCH v6 02/10] x86, mpx: add MPX specific mmap interface

On 06/23/2014 01:06 PM, Andy Lutomirski wrote:
> Can the new vm_operation "name" be use for this?  The magic "always
> written to core dumps" feature might need to be reconsidered.

One thing I'd like to avoid is an MPX vma getting merged with a non-MPX
vma.  I don't see any code to prevent two VMAs with different
vm_ops->names from getting merged.  That seems like a bit of a design
oversight for ->name.  Right?

Thinking out loud a bit... There are also some more complicated but more
performant cleanup mechanisms that I'd like to go after in the future.
Given a page, we might want to figure out if it is an MPX page or not.
I wonder if we'll ever collide with some other user of vm_ops->name.  It
looks fairly narrowly used at the moment, but would this keep us from
putting these pages on, say, a tmpfs mount?  Doesn't look that way at
the moment.
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