Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression

[David Rientjes]

On Wed, 5 Dec 2018, Linus Torvalds wrote:

> > So ultimately we decided that the saner behavior that gives the least
> > risk of regression for the short term, until we can do something
> > better, was the one that is already applied upstream.
> 
> You're ignoring the fact that people *did* report things regressed.
> 
> That's the part I find unacceptable. You're saying "we picked
> something that minimized regressions".
> 
> No it didn't. The regression is present and real, and is on a real
> load, not a benchmark.
> 
> So that argument is clearly bogus.
> 
> I'm going to revert the commit since people apparently seem to be
> ignoring this fundamental issue.
> 
> Real workloads regressed.  The regressions got reported. Ignoring that
> isn't acceptable.
> 

Please allow me to prepare my v2 because it's not a clean revert due to 
the follow-up 89c83fb539f9 ("mm, thp: consolidate THP gfp handling into 
alloc_hugepage_direct_gfpmask") and will incorporate the feedback from 
Michal to not change anything outside of the thp fault path.