linux-kernel - Re: [RFC] Initial alpha-0 for new page allocator API

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:	Fri, 22 Sep 2006 12:17:06 -0700 (PDT)
From:	Christoph Lameter <clameter@....com>
To:	Andi Kleen <ak@...e.de>
cc:	Martin Bligh <mbligh@...igh.org>, akpm@...gle.com,
	linux-kernel@...r.kernel.org,
	Christoph Hellwig <hch@...radead.org>,
	James Bottomley <James.Bottomley@...eleye.com>,
	linux-mm@...ck.org
Subject: Re: [RFC] Initial alpha-0 for new page allocator API

On Fri, 22 Sep 2006, Andi Kleen wrote:

> We already have that scheme. Any existing driver should be already converted
> away from GFP_DMA towards dma_*/pci_*. dma_* knows all the magic
> how to get memory for the various ranges. No need to mess up the 
> main allocator.

That is not the case. The "magic" ends in arch specific 
*_alloc_dma_coherent function tinkering around with __GFP_DMA and in 
x86_64 in addition GFP_DMA32.
> 
> Anyways, i suppose what could be added as a fallback would be a 
> really_slow_brute_force_try_to_get_something_in_this_range() allocator
> that basically goes through the buddy lists freeing in >O(1) 
> and does some directed reclaim, but that would likely be a separate
> path anyways and not need your new structure to impact the O(1)
> allocator.

Right.

> I am still unconvinced of the real need. The only gaping hole was 
> GFP_DMA32, which we fixed already.

And then about DMA zones being associated with arch independent memory 
ranges which is not the case. GFP_DMA32 just happens to be defined by a
single arch and thus is has only one interpretation.

> Ok there is aacraid with its weird 2GB limit, but in case there are
> really enough users running into this broken then then the really_slow_*
> thing above would be likely fine. And those cards are slowly going
> away too.  

I agree.

-
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/