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Date:   Thu, 23 Jul 2020 19:36:00 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Joonsoo Kim <js1304@gmail.com>
Cc:     Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, kernel-team@lge.com,
        Vlastimil Babka <vbabka@suse.cz>,
        Christoph Hellwig <hch@infradead.org>,
        Roman Gushchin <guro@fb.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Michal Hocko <mhocko@suse.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>, stable@vger.kernel.org
Subject: Re: [PATCH v2] mm/page_alloc: fix memalloc_nocma_{save/restore}
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On Fri, 24 Jul 2020 11:23:52 +0900 Joonsoo Kim <js1304@gmail.com> wrote:

> > > Second, clearing __GFP_MOVABLE in current_gfp_context() has a side effect
> > > to exclude the memory on the ZONE_MOVABLE for allocation target.
> >
> > More whoops.
> >
> > Could we please have a description of the end-user-visible effects of
> > this change?  Very much needed when proposing a -stable backport, I think.
> 
> In fact, there is no noticeable end-user-visible effect since the fallback would
> cover the problematic case. It's mentioned in the commit description. Perhap,
> performance would be improved due to reduced retry and more available memory
> (we can use ZONE_MOVABLE with this patch) but it would be neglectable.
> 
> > d7fefcc8de9147c is over a year old.  Why did we only just discover
> > this?  This makes one wonder how serious those end-user-visible effects
> > are?
> 
> As mentioned above, there is no visible problem to the end-user.

OK, thanks.  In that case, I don't believe that a stable backport is
appropriate?

(Documentation/process/stable-kernel-rules.rst)