Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752126AbbGEQiZ (ORCPT <rfc822;w@1wt.eu>);
	Sun, 5 Jul 2015 12:38:25 -0400
Received: from mail-wg0-f46.google.com ([74.125.82.46]:33157 "EHLO
	mail-wg0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751271AbbGEQiQ (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Sun, 5 Jul 2015 12:38:16 -0400
Message-ID: <55995D75.4020001@plexistor.com>
Date: Sun, 05 Jul 2015 19:38:13 +0300
From: Boaz Harrosh <boaz@plexistor.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0
MIME-Version: 1.0
To: "Kirill A. Shutemov" <kirill@shutemov.name>,
        Boaz Harrosh <boaz@plexistor.com>
CC: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
        Hugh Dickins <hughd@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] mm: avoid setting up anonymous pages into file mapping
References: <1435932447-84377-1-git-send-email-kirill.shutemov@linux.intel.com> <55994A08.3030308@plexistor.com> <20150705154441.GA4682@node.dhcp.inet.fi>
In-Reply-To: <20150705154441.GA4682@node.dhcp.inet.fi>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1502
Lines: 53

On 07/05/2015 06:44 PM, Kirill A. Shutemov wrote:
>> Again that could mean a theoretical regression for some in-tree driver,
>> do you know of any such driver?
> 
> I did very little testing with the patch: boot kvm with Fedora and run
> trinity there for a while. More testing is required.
> 

It seems more likely to be a bug in some obscure real HW driver, then
anything virtualized.

Let me run a quick search and see if I can see any obvious candidates
for this ...

<arch/x86/kernel/vsyscall_64.c>
static struct vm_operations_struct gate_vma_ops = {
	.name = gate_vma_name,
};

Perhaps it was done for this one
</arch/x86/kernel/vsyscall_64.c>

<arch/x86/mm/mpx.c>
static struct vm_operations_struct mpx_vma_ops = {
	.name = mpx_mapping_name,
};

Or this

</arch/x86/mm/mpx.c>

<more>
static const struct vm_operations_struct pci_mmap_ops = {

static const struct vm_operations_struct mmap_mem_ops = {

...
</more>

I was looking in-tree for any vm_operations_struct declaration without a .fault
member, there are these above and a slue of HW drivers that only have an .open
and .close so those might populate at open time and never actually ever fault.

Please have a quick look, I did not. I agree about the possible security badness.

Thanks
Boaz

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/