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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WARNING: multiple messages have this Message-ID (diff)
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."
next prev parent reply other threads:[~2014-12-14 23:08 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-14 20:22 [GIT PULL] aio: changes for 3.19 Benjamin LaHaise
2014-12-14 20:22 ` Benjamin LaHaise
2014-12-14 21:47 ` Linus Torvalds
2014-12-14 21:47 ` Linus Torvalds
2014-12-14 21:52 ` Benjamin LaHaise
2014-12-14 21:52 ` Benjamin LaHaise
2014-12-14 22:09 ` Linus Torvalds
2014-12-14 22:09 ` Linus Torvalds
2014-12-14 22:13 ` Andrew Morton
2014-12-14 22:13 ` Andrew Morton
2014-12-14 22:39 ` Benjamin LaHaise
2014-12-14 22:39 ` Benjamin LaHaise
2014-12-15 5:53 ` Andrew Morton
2014-12-15 5:53 ` Andrew Morton
2014-12-14 23:02 ` Kirill A. Shutemov
2014-12-14 23:02 ` Kirill A. Shutemov
2014-12-14 23:08 ` Benjamin LaHaise [this message]
2014-12-14 23:08 ` Benjamin LaHaise
2014-12-14 23:11 ` Linus Torvalds
2014-12-14 23:11 ` Linus Torvalds
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