From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Larry Finger <Larry.Finger@lwfinger.net>
Subject: Re: [Bug #13319] Page allocation failures with b43 and p54usb
Date: Tue, 30 Jun 2009 01:15:26 +0200
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Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Kernel Testers List <kernel-testers@vger.kernel.org>,
       Johannes Berg <johannes@sipsolutions.net>
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On Monday 29 June 2009, Larry Finger wrote:
> Rafael J. Wysocki wrote:
> > This message has been generated automatically as a part of a report
> > of regressions introduced between 2.6.29 and 2.6.30.
> > 
> > The following bug entry is on the current list of known regressions
> > introduced between 2.6.29 and 2.6.30.  Please verify if it still should
> > be listed and let me know (either way).
> > 
> > 
> > Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13319
> > Subject		: Page allocation failures with b43 and p54usb
> > Submitter	: Larry Finger <Larry.Finger@lwfinger.net>
> > Date		: 2009-04-29 21:01 (61 days old)
> > References	: http://marc.info/?l=linux-kernel&m=124103897101088&w=4
> > 		  http://lkml.org/lkml/2009/6/7/136
> > Handled-By	: Johannes Berg <johannes@sipsolutions.net>
> 
> The cause of these failures has been determined. The wireless
> subsystem frequently requests buffers of size 4096, but when SLUB
> debugging is enabled and the debug info is added, the request becomes
> of order 1 and memory becomes fragmented.
> 
> A controversial "fix" in which SLUB debugging was disabled for
> allocations where adding such debugging info would increase the order
> was discussed and tried. With a quick look at the commit list for
> Linus's tree, I don't see that such a patch is available, but I will
> be corrected if I missed it.

Thanks for the update.

Hmm, isn't it suboptimal to use a slab allocator for allocations taking up an
entire page?  That's the case on some architectures and seems to be the root
cause of the issue at hand.

Best,
Rafael
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