Re: [PATCH 01/19] tree wide: get rid of __GFP_REPEAT for order-0 allocations part I

[David Rientjes]

On Mon, 11 Apr 2016, Michal Hocko wrote:

> From: Michal Hocko <mhocko@xxxxxxxx>
> 
> __GFP_REPEAT has a rather weak semantic but since it has been introduced
> around 2.6.12 it has been ignored for low order allocations. Yet we have
> the full kernel tree with its usage for apparently order-0 allocations.
> This is really confusing because __GFP_REPEAT is explicitly documented
> to allow allocation failures which is a weaker semantic than the current
> order-0 has (basically nofail).
> 
> Let's simply drop __GFP_REPEAT from those places. This would allow
> to identify place which really need allocator to retry harder and
> formulate a more specific semantic for what the flag is supposed to do
> actually.
> 
> Cc: linux-arch@xxxxxxxxxxxxxxx
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>

I did exactly this before, and Andrew objected saying that __GFP_REPEAT 
may not be needed for the current page allocator's implementation but 
could with others and that setting __GFP_REPEAT for an allocation 
provided useful information with regards to intent.  At the time, I 
attempted to eliminate __GFP_REPEAT entirely.