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Date:   Thu, 12 Jan 2023 09:38:12 +0000
From:   Mel Gorman <mgorman@techsingularity.net>
To:     Michal Hocko <mhocko@suse.com>
Cc:     Linux-MM <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        NeilBrown <neilb@suse.de>,
        Thierry Reding <thierry.reding@gmail.com>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/7] mm/page_alloc: Explicitly record high-order atomic
 allocations in alloc_flags
Message-ID: <20230112093812.x7kgdgvyd2fzrwex@techsingularity.net>
References: <20230109151631.24923-1-mgorman@techsingularity.net>
 <20230109151631.24923-4-mgorman@techsingularity.net>
 <Y77XYW/81sfSXCj9@dhcp22.suse.cz>
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On Wed, Jan 11, 2023 at 04:36:01PM +0100, Michal Hocko wrote:
> On Mon 09-01-23 15:16:27, Mel Gorman wrote:
> > A high-order ALLOC_HARDER allocation is assumed to be atomic. While that
> > is accurate, it changes later in the series. In preparation, explicitly
> > record high-order atomic allocations in gfp_to_alloc_flags(). There is
> > a slight functional change in that OOM handling avoids using high-order
> > reserve until it has to.
> 
> I do not follow the oom handling part. IIRC we are dropping highatomic
> reserves before triggering oom. Something might have changed down the
> path but I can still see unreserve_highatomic_pageblock in
> should_reclaim_retry.
> 

That comment is now stale and should be removed because I fixed up the
OOM oddities. At this point, a series resubmission is needed because a
few changelogs have to be updated.

-- 
Mel Gorman
SUSE Labs