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SubjectRe: [Bug #13319] Page allocation failures with b43 and p54usb
On Mon, 29 Jun 2009, Larry Finger wrote:

> > Bug-Entry :
> > Subject : Page allocation failures with b43 and p54usb
> > Submitter : Larry Finger <>
> > Date : 2009-04-29 21:01 (61 days old)
> > References :
> >
> > Handled-By : Johannes Berg <>
> 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.

I'd disagree with disabling slub debugging by default for caches where
oo_order(s->min) increases as the result of using it. This particular
page allocation failure is happening for, presumably, kmalloc-4096, and
the system has 4K pages. Disabling debugging for that cache (and any of
its aliases) implicitly will lead to errors going undiagnosed as a result.

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