linux-kernel - Re: [PATCHv3 03/17] mm/ksm: Do not merge pages with different KeyIDs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <355d6b1f-9188-e93b-9cf1-01ece1879cad@intel.com>
Date:   Wed, 13 Jun 2018 13:35:46 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Kai Huang <kai.huang@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv3 03/17] mm/ksm: Do not merge pages with different KeyIDs

On 06/13/2018 01:31 PM, Kirill A. Shutemov wrote:
>> What actually happens without this patch in place?
> 
> One of processes would get the page mapped with wrong KeyID and see
> garbage. 

OK, but what about two pages with the same KeyID?  It's actually totally
possible for KSM to determine that two pages have the same plaintext and
merge them.  Why don't we do that?

> We setup mapping according to KeyID in vma->vm_page_prot.

Then why do we bother with page_keyid() and the page_ext stuff?