linux-kernel - Re: [Intel IOMMU 06/10] Avoid memory allocation failures in dma map api calls

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1182297754.2700.1.camel@laptopd505.fenrus.org>
Date:	Tue, 19 Jun 2007 17:02:34 -0700
From:	Arjan van de Ven <arjan@...ux.intel.com>
To:	Christoph Lameter <clameter@....com>
Cc:	"Keshavamurthy, Anil S" <anil.s.keshavamurthy@...el.com>,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	ak@...e.de, gregkh@...e.de, muli@...ibm.com,
	suresh.b.siddha@...el.com, ashok.raj@...el.com, davem@...emloft.net
Subject: Re: [Intel IOMMU 06/10] Avoid memory allocation failures in dma
	map api calls

On Tue, 2007-06-19 at 16:34 -0700, Christoph Lameter wrote:
> On Tue, 19 Jun 2007, Arjan van de Ven wrote:
> 
> > > Otherwise you are locked into the use of GFP_ATOMIC.
> > 
> > all callers pretty much are either in irq context or with spinlocks held. Good
> > luck..... it's also called primarily from the PCI DMA API which doesn't take a
> > gfp_t argument in the first place...
> > 
> > so I'm not seeing the point.
> 
> Hmmm... From my superficial look at things it seems that one could avoid 
> GFP_ATOMIC at times. 

by changing ALL drivers. And then you realize the common scenario is
that it's taken in irq context ;)

> I do not know too much about the driver though but it 
> seems a bit restrictive to always do GFP_ATOMIC allocs.

the only alternative to GFP_ATOMIC is GFP_NOIO which is... barely
better. And then add that it can be used only sporadic...
feel free to first change all the drivers.. once the callers of these
functions have a gfp_t then I'm sure Anil will be happy to take one of
those as well ;-)

-
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/