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Subject: Re: [PATCH] mm, thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings
From: Vlastimil Babka <vbabka@suse.cz>
References: <39BE14E6-D0FB-428A-B062-8B5AEDC06E61@cs.rutgers.edu>
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Date: Thu, 6 Sep 2018 13:16:00 +0200
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To: Michal Hocko <mhocko@suse.com>, Andrea Arcangeli <aarcange@redhat.com>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>, Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org, Alex Williamson <alex.williamson@redhat.com>, David Rientjes <rientjes@google.com>, Stefan Priebe - Profihost AG <s.priebe@profihost.ag>

On 09/06/2018 01:10 PM, Vlastimil Babka wrote:
>> We can and should think about this much more but I would like to have
>> this regression closed. So can we address GFP_THISNODE part first and
>> build more complex solution on top?
>>
>> Is there any objection to my patch which does the similar thing to your
>> patch v2 in a different location?
> 
> Similar but not the same. It fixes the madvise case, but I wonder about
> the no-madvise defrag=defer case, where Zi Yan reports it still causes
> swapping.

Ah, but that should be the same with Andrea's variant 2) patch. There
should only be difference with defrag=always, which is direct reclaim
with __GFP_NORETRY, Andrea's patch would drop __GFP_THISNODE and your
not. Maybe Zi Yan can do the same kind of tests with Andrea's patch [1]
to confirm?

[1] https://marc.info/?l=linux-mm&m=153476267026951