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Date: Thu, 1 Mar 2018 15:38:08 -0800 (PST)
From: David Rientjes <rientjes@google.com>
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To: Andrew Morton <akpm@linux-foundation.org>
cc: Vlastimil Babka <vbabka@suse.cz>,
        Mel Gorman <mgorman@techsingularity.net>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [patch] mm, compaction: drain pcps for zone when kcompactd
 fails
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On Thu, 1 Mar 2018, Andrew Morton wrote:

> On Thu, 1 Mar 2018 03:42:04 -0800 (PST) David Rientjes <rientjes@google.com> wrote:
> 
> > It's possible for buddy pages to become stranded on pcps that, if drained,
> > could be merged with other buddy pages on the zone's free area to form
> > large order pages, including up to MAX_ORDER.
> 
> I grabbed this as-is.  Perhaps you could send along a new changelog so
> that others won't be asking the same questions as Vlastimil?
> 
> The patch has no reviews or acks at this time...
> 

Thanks.

As mentioned in my response to Vlastimil, I think the case could also be 
made that we should do drain_all_pages(zone) in try_to_compact_pages() 
when we defer for direct compactors.  It would be great to have feedback 
from those on the cc on that point, the patch in general, and then I can 
send an update.