From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boaz Harrosh <boaz@plexistor.com>
Subject: Re: [PATCH] mm: avoid setting up anonymous pages into file mapping
Date: Sun, 05 Jul 2015 19:38:13 +0300
Message-ID: <55995D75.4020001@plexistor.com>
References: <1435932447-84377-1-git-send-email-kirill.shutemov@linux.intel.com> <55994A08.3030308@plexistor.com> <20150705154441.GA4682@node.dhcp.inet.fi>
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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
To: "Kirill A. Shutemov" <kirill@shutemov.name>,
 Boaz Harrosh <boaz@plexistor.com>
Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <20150705154441.GA4682@node.dhcp.inet.fi>
Sender: owner-linux-mm@kvack.org
List-Id: linux-fsdevel.vger.kernel.org

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

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