Re: [Bug #13319] Page allocation failures with b43 and p54usb

Rafael J. Wysocki
2009-06-29T23:15:23Z

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