Re: [PATCH 1/2] mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings

From: Michal Hocko
Date: Wed Oct 17 2018 - 03:08:31 EST

On Tue 16-10-18 16:16:43, Andrew Morton wrote:
> On Tue, 16 Oct 2018 19:11:49 -0400 Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote:
> > This was a severe regression
> > compared to previous kernels that made important workloads unusable
> > and it starts when __GFP_THISNODE was added to THP allocations under
> > MADV_HUGEPAGE. It is not a significant risk to go to the previous
> > behavior before __GFP_THISNODE was added, it worked like that for
> > years.@s1@s2@s1
> 5265047ac301 ("mm, thp: really limit transparent hugepage allocation to
> local node") was April 2015. That's a long time for a "severe
> regression" to go unnoticed?

Well, it gets some time to adopt changes in enterprise and we start
seeing people reporting this issue. That is why I believe we should
start with something really simple and stable tree backportable first
and then build something more complex on top.
Michal Hocko