Re: upcoming kerneloops.org item: get_page_from_freelist

[Pekka Enberg <penberg@cs.helsinki.fi>]

Hi Andrew,

Andrew Morton wrote:
> On Wed, 24 Jun 2009 19:55:24 +0300 Pekka Enberg <penberg@cs.helsinki.fi> wrote:
> 
>> On Wed, Jun 24, 2009 at 7:46 PM, Andrew Morton<akpm@linux-foundation.org> wrote:
>>> Well yes. __Using GFP_NOFAIL on a higher-order allocation is bad. __This
>>> patch is there to find, name, shame, blame and hopefully fix callers.
>>>
>>> A fix for cxgb3 is in the works. __slub's design is a big problem.
>>>
>>> But we'll probably have to revert it for 2.6.31 :(
>> How is SLUB's design a problem here? Can't we just clear GFP_NOFAIL
>> from the higher order allocation and thus force GFP_NOFAIL allocations
>> to use the minimum required order?
> 
> That could then lead to the __GFP_NOFAIL allocation attempt returning
> NULL.  But the callers cannot handle that and probably don't even test
> for it - this is why they used __GFP_NOFAIL.

No, the fallback allocation would still use __GFP_NOFAIL so the 
semantics are preserved.

			Pekka