linux-kernel - Re: [RFC] Restrict size of page

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: <20101007040802.GO4195@balbir.in.ibm.com>
Date:	Thu, 7 Oct 2010 09:38:02 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Cc:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	containers@...ts.linux-foundation.org,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC] Restrict size of page_cgroup->flags

* nishimura@....nes.nec.co.jp <nishimura@....nes.nec.co.jp> [2010-10-07 12:47:06]:

> On Thu, 7 Oct 2010 08:44:59 +0530
> Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> 
> > * nishimura@....nes.nec.co.jp <nishimura@....nes.nec.co.jp> [2010-10-07 09:54:58]:
> > 
> > > On Wed, 6 Oct 2010 19:53:14 +0530
> > > Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> > > 
> > > > I propose restricting page_cgroup.flags to 16 bits. The patch for the
> > > > same is below. Comments?
> > > > 
> > > > 
> > > > Restrict the bits usage in page_cgroup.flags
> > > > 
> > > > From: Balbir Singh <balbir@...ux.vnet.ibm.com>
> > > > 
> > > > Restricting the flags helps control growth of the flags unbound.
> > > > Restriciting it to 16 bits gives us the possibility of merging
> > > > cgroup id with flags (atomicity permitting) and saving a whole
> > > > long word in page_cgroup
> > > > 
> > > I agree that reducing the size of page_cgroup would be good and important.
> > > But, wouldn't it be better to remove ->page, if possible ?
> > >
> > 
> > Without the page pointer, how do we go from pc to page for reclaim? 
> > 
> We store page_cgroups in arrays now, so I suppose we can implement pc_to_pfn()
> using the similar calculation as page_to_pfn() does.
> IIRC, KAMEZAWA-san talked about it in another thread.
>

Yes, correct we do. Your suggestions, IIUC is to reuse part of the
flags to store the section number where the pc belongs and then use
that to remove ->page pointer.

-- 
	Three Cheers,
	Balbir
--
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/