linux-kernel - Re: [v2 RFC PATCH 0/9] Another Approach to Use PMEM as NUMA Node

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]

Date:   Tue, 16 Apr 2019 16:39:58 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Yang Shi <yang.shi@...ux.alibaba.com>, mgorman@...hsingularity.net,
        riel@...riel.com, hannes@...xchg.org, akpm@...ux-foundation.org,
        keith.busch@...el.com, dan.j.williams@...el.com,
        fengguang.wu@...el.com, fan.du@...el.com, ying.huang@...el.com,
        ziy@...dia.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [v2 RFC PATCH 0/9] Another Approach to Use PMEM as NUMA Node

On Tue 16-04-19 07:30:20, Dave Hansen wrote:
> On 4/16/19 12:47 AM, Michal Hocko wrote:
> > You definitely have to follow policy. You cannot demote to a node which
> > is outside of the cpuset/mempolicy because you are breaking contract
> > expected by the userspace. That implies doing a rmap walk.
> 
> What *is* the contract with userspace, anyway? :)
> 
> Obviously, the preferred policy doesn't have any strict contract.
> 
> The strict binding has a bit more of a contract, but it doesn't prevent
> swapping.

Yes, but swapping is not a problem for using binding for memory
partitioning.

> Strict binding also doesn't keep another app from moving the
> memory.

I would consider that a bug.
-- 
Michal Hocko
SUSE Labs