linux-kernel - Re: [RFC][PATCH 1/5] memcg: change for softlimit.

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: <d50640bcbd1bb174caaca9714bbe03e5.squirrel@webmail-b.css.fujitsu.com>
Date:	Fri, 28 Aug 2009 23:58:39 +0900 (JST)
From:	"KAMEZAWA Hiroyuki" <kamezawa.hiroyu@...fujitsu.com>
To:	balbir@...ux.vnet.ibm.com
Cc:	"KAMEZAWA Hiroyuki" <kamezawa.hiroyu@...fujitsu.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>
Subject: Re: [RFC][PATCH 1/5] memcg: change for softlimit.

Balbir Singh wrote:
> * KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2009-08-28
> 23:29:09]:
>
>> Balbir Singh wrote:
>> > * KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2009-08-28
>> > 16:35:23]:
>> >
>>
>> >>
>> >> Current soft-limit RB-tree will be easily broken i.e. not-sorted
>> >> correctly
>> >> if used under use_hierarchy=1.
>> >>
>> >
>> > Not true, I think the sorted-ness is delayed and is seen when we pick
>> > a tree for reclaim. Think of it as being lazy :)
>> >
>> plz explain how enexpectedly unsorted RB-tree can work sanely.
>>
>>
>
> There are two checks built-in
>
> 1. In the reclaim path (we see how much to reclaim, compared to the
> soft limit)
> 2. In the dequeue path where we check if we really are over soft limit
>
that's not a point.

> I did lot of testing with the time based approach and found no broken
> cases, I;ve been testing it with the mmotm (event based approach and I
> am yet to see a broken case so far).
>
I'm sorry if I don't understand RB-tree.
I think RB-tree is a system which can sort inputs passed by caller
one by one and will be in broken state if value of nodes changed
while it's in tree. Wrong ?
While a subtree is
               7
              / \
             3   9
And, by some magic, the value can be changed without extract
               7
              / \
             13  9
The biggest is 13. But the biggest number which will be selecte will be "9".

Thanks,
-Kame







--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/