Re: [PATCH] SLUB: Do not fallback to mininum order if __GFP_NORETRY is set

[Christopher Lameter]

On Thu, 19 Apr 2018, Michal Hocko wrote:

> Overriding __GFP_NORETRY is just a bad idea. It will make the semantic
> of the flag just more confusing. Note there are users who use
> __GFP_NORETRY as a way to suppress heavy memory pressure and/or the OOM
> killer. You do not want to change the semantic for them.

Redoing the allocation after failing a large order alloc is a retry. I
would say its confusing right now because a retry occurs despite
specifying GFP_NORETRY,

> Besides that the changelog is less than optimal. What is the actual
> problem? Why somebody doesn't want a fallback? Is there a configuration
> that could prevent the same?

The problem is that SLUB does not honor GFP_NORETRY. The semantics of
GFP_NORETRY are not followed.