linux-kernel - Re: [PATCH] module: kzalloc mod->ref

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, 14 Jan 2009 17:25:31 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Kyle McMartin <kyle@...radead.org>
Cc:	rusty@...tcorp.com.au, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] module: kzalloc mod->ref

At Wed, 14 Jan 2009 10:58:59 -0500,
Kyle McMartin wrote:
> 
> On Wed, Jan 14, 2009 at 10:09:59AM +0100, Takashi Iwai wrote:
> > At Tue, 13 Jan 2009 22:35:33 -0500,
> > Kyle McMartin wrote:
> > > 
> > > From: Kyle McMartin <kyle@...hat.com>
> > > 
> > > Dynamically allocate mod->ref instead of fixing it in the struct module.
> > > Reduces on disk space wasted in the module .ko, and kills a loop
> > > initializing the local_t it contains since we can just kzalloc it.
> > > 
> > > This matters when we're talking about large NR_CPUS.
> > > 
> > > Signed-off-by: Kyle McMartin <kyle@...hat.com>
> > > ---
> > > The patch removing cacheline_aligned from struct module_ref should be
> > > applied as well to cut down on the amount of memory we allocate. This
> > > patch makes a nice stopgap until we have per_cpu module references.
> > > 
> > > cheers, Kyle
> > 
> > Similar patches (including mine) have been already posted, but no
> > proceed until now...
> > 	http://lkml.org/lkml/2008/11/11/315
> 
> Ah, sigh.
> 
> It would be nice to get this sorted out, since we're serious wasting
> disk space for no good reason...
> 
> Although as Richard points out, dropping the cacheline_aligned might
> drop networking performance (which, sigh, is also stupid) but allocating
> 128b * NR_CPUS is just a ridiculous amount of memory to waste for a
> reference count...

We can use nr_cpu_ids instead of NR_CPUS.
For a machine like 4096 CPUs, such an amount of memory is like a
peanut :)


Takashi
--
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/