linux-kernel - Re: [PATCH 1/7] mm: introduce simple_malloc()/simple

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: <4920D238.8090905@cn.fujitsu.com>
Date:	Mon, 17 Nov 2008 10:08:56 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	Arjan van de Ven <arjan@...radead.org>
CC:	Dave Airlie <airlied@...il.com>,
	David Miller <davem@...emloft.net>, akpm@...ux-foundation.org,
	menage@...gle.com, kamezawa.hiroyu@...fujitsu.com,
	balbir@...ux.vnet.ibm.com, jens.axboe@...cle.com, jack@...e.cz,
	jes@....com, linux-kernel@...r.kernel.org,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	dada1@...mosbay.com, Alexey Dobriyan <adobriyan@...il.com>
Subject: Re: [PATCH 1/7] mm: introduce simple_malloc()/simple_free()

Arjan van de Ven wrote:
> On Mon, 17 Nov 2008 07:39:55 +1000
> 
> I would go further than this.
> 
> Make the code just use vmalloc(). Period.
> 
> But then make vmalloc() smart and try do a direct mapping allocation
> first, before falling back to a virtual mapping. (and based on size it
> wouldn't even try it for just big things)
> 
> 
> 

Hi, Arjan van de Ven

(I'll rename simple_malloc/simple_free to kvmalloc/kvfree)

I think vmalloc() should only do one thing(virtual mapping). Your idea
can be implemented in helper function kvmalloc() if there is a good
algorithm provided for it.

kvmalloc() is for cleanup mostly. It will remove existed duplicate code.
As David and I pointed out, vmalloc() is need for some good reason.

If we do not introduce a helper function, these duplicate code
are still spread everywhere.

kvfree() is not only for free the memory allocated by kvmalloc().

kvfree() frees the memory that we don't know whether it was allocated
by kmalloc() nor vmalloc().

Someone use a flag for it, and other guys calculate size of memory again
before kfree() or vfree(). these two ways increase complexity, and
it is hard to prove the re-calculated size is reliable.

kvfree() will remove these needless complexity!

Thanx, Lai

--
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/