linux-kernel - Re: [PATCH v6] zswap: memcontrol: implement zswap writeback disabling

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] [day] [month] [year] [list]

Date: Fri, 15 Dec 2023 10:50:16 +0100
From: Fabian Deutsch <fdeutsch@...hat.com>
To: Chris Li <chrisl@...nel.org>
Cc: Yu Zhao <yuzhao@...gle.com>, Johannes Weiner <hannes@...xchg.org>, 
	Minchan Kim <minchan@...nel.org>, Nhat Pham <nphamcs@...il.com>, 
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "tj@...nel.org" <tj@...nel.org>, 
	"lizefan.x@...edance.com" <lizefan.x@...edance.com>, 
	"cerasuolodomenico@...il.com" <cerasuolodomenico@...il.com>, 
	"yosryahmed@...gle.com" <yosryahmed@...gle.com>, "sjenning@...hat.com" <sjenning@...hat.com>, 
	"ddstreet@...e.org" <ddstreet@...e.org>, "vitaly.wool@...sulko.com" <vitaly.wool@...sulko.com>, 
	"mhocko@...nel.org" <mhocko@...nel.org>, "roman.gushchin@...ux.dev" <roman.gushchin@...ux.dev>, 
	"shakeelb@...gle.com" <shakeelb@...gle.com>, "muchun.song@...ux.dev" <muchun.song@...ux.dev>, 
	"hughd@...gle.com" <hughd@...gle.com>, "corbet@....net" <corbet@....net>, 
	"konrad.wilk@...cle.com" <konrad.wilk@...cle.com>, 
	"senozhatsky@...omium.org" <senozhatsky@...omium.org>, "rppt@...nel.org" <rppt@...nel.org>, 
	"linux-mm@...ck.org" <linux-mm@...ck.org>, "kernel-team@...a.com" <kernel-team@...a.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>, "david@...t.cz" <david@...t.cz>, 
	Kairui Song <kasong@...cent.com>, Zhongkun He <hezhongkun.hzk@...edance.com>
Subject: Re: [PATCH v6] zswap: memcontrol: implement zswap writeback disabling

On Fri, Dec 15, 2023 at 10:40 AM Chris Li <chrisl@...nel.org> wrote:
>
> On Thu, Dec 14, 2023 at 11:42 PM Fabian Deutsch <fdeutsch@...hat.com> wrote:.
> > >
> > > Just to clarify, the "node" you mean the "node" in kubernetes sense,
> > > which is the whole machine. In the Linux kernel MM context, the node
> > > often refers to the NUMA memory node, that is not what you mean here,
> > > right?
> >
> > Correct, I was referring to a kubernetes node, not numa node.
> >
> > >
> > >> - With todays node level swap, and setting memory.swap.max=0 for all cgroups allows you toachieve a similar behavior (only opt-in cgroups will get swap).
> > >> - the above approach however will still have a shared swap backend for all cgroups.
> > >
> > > Yes, the "memory.swap.tires" idea is trying to allow cgroups to select
> > > a subset of the swap backend in a specific order. It is still in the
> > > early stage of discussion. If you have any suggestion or feedback in
> > > that direction, I am looking forward to hearing that.
> >
> > Interesting. There have been concerns to leak confidential data accidentally when it's getting written to a swap device.
>
> One common solution is to encrypt the data written to the device. If
> someone gets hold of the swapped outed device without the key, they
> can't get to the memory data without the key.


Yes - I guess like writing it onto a dmcrypt device with some random key.
Nevertheless, this was one of the topics.

>
>
> > The other less discussed item was QoS for swap io traffic.
> >
> > At a first glance it seems like tires could help with the second use-case.
>
> The idea is that you can select the swap tiers list for each cgroup.
> That way  you can assign different swap QoS to different cgroup.


Yes, it sounds like a fit.
What use-cases did you have in mind for the tiers feature?