linux-kernel - RE: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP

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: <AM6PR0502MB3783280D15C96E5A3A831DCBBD4C0@AM6PR0502MB3783.eurprd05.prod.outlook.com>
Date:   Tue, 17 Oct 2017 14:20:55 +0000
From:   Guy Shattah <sguy@...lanox.com>
To:     Michal Nazarewicz <mina86@...a86.com>,
        Michal Hocko <mhocko@...nel.org>
CC:     Christopher Lameter <cl@...ux.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>,
        Laura Abbott <labbott@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: RE: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP_CONTIG) support



> On Tue, Oct 17 2017, Guy Shattah wrote:
> > Are you going to be OK with kernel API which implements contiguous
> > memory allocation?  Possibly with mmap style?  Many drivers could
> > utilize it instead of having their own weird and possibly non-standard
> > way to allocate contiguous memory.  Such API won't be available for
> > user space.
> 
> What you describe sounds like CMA.  It may be far from perfect but it’s there
> already and drivers which need contiguous memory can allocate it.
> 

1. CMA has to preconfigured. We're suggesting mechanism that works 'out of the box'
2. Due to the pre-allocation techniques CMA imposes limitation on maximum 
   allocated memory. RDMA users often require 1Gb or more, sometimes more.
3. CMA reserves memory in advance, our suggestion is using existing kernel memory
     mechanisms (THP for example) to allocate memory. 

Guy