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: Windows password security audit tool. GUI, reports in PDF.

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

Message-Id: <1182409991.21117.112.camel@twins>
Date:	Thu, 21 Jun 2007 09:13:11 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	"Keshavamurthy, Anil S" <anil.s.keshavamurthy@...el.com>
Cc:	Arjan van de Ven <arjan@...ux.intel.com>,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	ak@...e.de, gregkh@...e.de, muli@...ibm.com, ashok.raj@...el.com,
	davem@...emloft.net, clameter@....com
Subject: Re: [Intel IOMMU 06/10] Avoid memory allocation
	failures	in	dma	map api calls

On Wed, 2007-06-20 at 23:37 -0700, Keshavamurthy, Anil S wrote:
> On Thu, Jun 21, 2007 at 08:29:34AM +0200, Peter Zijlstra wrote:
> > On Wed, 2007-06-20 at 23:11 -0700, Arjan van de Ven wrote:
> > > Peter Zijlstra wrote:
> > Also, the other iommu code you pointed me to, was happy to fail, it did
> > not attempt to use the emergency reserves.
> 
> Is the same behavior acceptable here?

I would say it is. Failure is a part of life.

If you have a (small) mempool with 16 pages or so, that should give you
plenty megabytes of io-space to get out of a tight spot. That is, you
can queue many pages with that. If it is depleted you know you have at
least that many pages outstanding. So failing will just delay the next
pages.

Throughput is not a key issue when that low on memory, a guarantee of
progress is.


-
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/