Re: Kernel 2.6.9 Multiple Page Allocation Failures

[Andrew Morton <akpm@xxxxxxxx>]

Nathan Scott <nathans@xxxxxxx> wrote:
>
> > Nathan, it would be a worthwhile exercise to consider replacing GFP_ATOMIC
>  > with (GFP_ATOMIC & ~ __GFP_HIGH) where appropriate.
>  > ...
> 
>  (i.e. zero?  so future-proofing for if GFP_ATOMIC != __GFP_HIGH?)

yup.  (GFP_ATOMIC & ~ __GFP_HIGH) would mean "allocate atomically, but if
this means use emergency pools, then don't bother with that".

>  > If there are places in XFS where it only needs one of these two behaviours,
>  > it would be good to select just that one.
> 
>  OK, I took a quick look through - there's two places where we use
>  GFP_ATOMIC at the moment.  One is a log debug/tracing chunk of code,
>  wont be coming into play here, I'll go back and rework that later.
>  The second is in the metadata buffering code, and is in a spot where
>  we can cope with a failure (don't need to dip into emergency pools
>  at all) but looks like we're avoiding sleeping there.

Just two callsites?  That's less that I imagined.  Looks like my theory
comes unstuck.