On 10/3/19 12:32 AM, David Rientjes wrote: > On Wed, 2 Oct 2019, Michal Hocko wrote: > >>>> If >>>> hugetlb wants to stress this to the fullest extent possible, it already >>>> appropriately uses __GFP_RETRY_MAYFAIL. >>> >>> Which doesn't work anymore right now, and should again after this patch. >> >> I didn't get to fully digest the patch Vlastimil is proposing. (Ab)using >> __GFP_NORETRY is quite subtle but it is already in place with some >> explanation and a reference to THPs. So while I am not really happy it >> is at least something you can reason about. >> > > It's a no-op: > > /* Do not loop if specifically requested */ > if (gfp_mask & __GFP_NORETRY) > goto nopage; > > /* > * Do not retry costly high order allocations unless they are > * __GFP_RETRY_MAYFAIL > */ > if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL)) > goto nopage; > > So I'm not sure we should spend too much time discussing a hunk of a patch > that doesn't do anything. I believe Michal was talking about my (ab)use of __GFP_NORETRY, where it controls the earlier 'goto nopage' condition. Yes, with your patches alone, the addition of __GFP_NORETRY in the second attempt is a no-op, although then I don't see the point of confusing people reading the code with it.
