linux-kernel - Re: [PATCH v6 11/12] zsmalloc: page migration support

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:	Wed, 25 May 2016 14:14:38 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [PATCH v6 11/12] zsmalloc: page migration support

Hello Sergey,

On Tue, May 24, 2016 at 03:28:01PM +0900, Minchan Kim wrote:
<snip>

> > hm... zsmalloc is getting sooo complex now.
> > 
> > `system_wq' -- can we have problems here when the system is getting
> > low on memory and workers are getting increasingly busy trying to
> > allocate the memory for some other purposes?
> > 
> > _theoretically_ zsmalloc can stack a number of ready-to-release zspages,
> > which won't be accessible to zsmalloc, nor will they be released. how likely
> > is this? hm, can zsmalloc take zspages from that deferred release list when
> > it wants to allocate a new zspage?
> 
> Done.
> 
> > 
> > do you also want to kick the deferred page release from the shrinker
> > callback, for example?
> 
> Yeb, it can be. I will do it at next revision. :)
> Thanks!
> 

I tried it now but I feel strongly we want to fix shrinker first.
Now, shrinker doesn't consider VM's request(i.e., sc->nr_to_scan) but
shrink all objects which could make latency huge.

I want to fix it as another issue and then adding ZS_EMPTY pool pages
purging logic based on it because many works for zsmalloc stucked
with this patchset now which churns old code heavily. :(