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From: Benjamin LaHaise <bcrl@kvack.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-aio@kvack.org, Linux Kernel <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Pavel Emelyanov <xemul@parallels.com>,
	Dmitry Monakhov <dmonakhov@openvz.org>
Subject: Re: [GIT PULL] aio: changes for 3.19
Date: Sun, 14 Dec 2014 18:08:09 -0500	[thread overview]
Message-ID: <20141214230809.GK2672@kvack.org> (raw)
In-Reply-To: <20141214230208.GA9217@node.dhcp.inet.fi>

On Mon, Dec 15, 2014 at 01:02:08AM +0200, Kirill A. Shutemov wrote:
> But it seems the problem is bigger than what the patch fixes. To me we are
> too permisive on what vma can be remapped.
> 
> How can we know that it's okay to move vma around for random driver which
> provide .mmap? Or I miss something obvious?

Most drivers do not care if a vma is moved within the virtual address space 
of a process.  The aio ring buffer is special in that it gets unmapped when 
userspace does an io_destroy(), and io_destroy() has to know what the address 
is moved to in order to perform the unmap.  Normal drivers don't perform the 
unmap themselves.

		-ben
-- 
"Thought is the essence of where you are now."

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  reply	other threads:[~2014-12-14 23:08 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-14 20:22 Benjamin LaHaise
2014-12-14 21:47 ` Linus Torvalds
2014-12-14 21:52   ` Benjamin LaHaise
2014-12-14 22:09     ` Linus Torvalds
2014-12-14 22:13     ` Andrew Morton
2014-12-14 22:39       ` Benjamin LaHaise
2014-12-15  5:53         ` Andrew Morton
2014-12-14 23:02       ` Kirill A. Shutemov
2014-12-14 23:08         ` Benjamin LaHaise [this message]
2014-12-14 23:11         ` Linus Torvalds

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