linux-kernel - Re: mm, vmscan: commit makes PAE kernel crash nightly (bisected)

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Date:   Tue, 24 Jan 2017 13:59:21 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Mel Gorman <mgorman@...hsingularity.net>
Cc:     Trevor Cordes <trevor@...nopolis.ca>, linux-kernel@...r.kernel.org,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Minchan Kim <minchan@...nel.org>,
        Rik van Riel <riel@...riel.com>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Subject: Re: mm, vmscan: commit makes PAE kernel crash nightly (bisected)

On Mon 23-01-17 10:48:58, Mel Gorman wrote:
[...]
> Unfortunately, even that will be race prone for GFP_NOFS callers as
> they'll effectively be racing to see if kswapd or another direct
> reclaimer can reclaim before the OOM conditions are hit. It is by
> design, but it's apparent that a __GFP_NOFAIL request can trigger OOM
> relatively easily as it's not necessarily throttled or waiting on kswapd
> to complete any work. I'll keep thinking about it.

Yes, we shouldn't trigger the OOM for GFP_NOFS as the memory reclaim is
really weaker. And that might really matter here. So the mmomt tree will
behave differently in this regards as we have [1]

[1] http://lkml.kernel.org/r/20161220134904.21023-3-mhocko@kernel.org
-- 
Michal Hocko
SUSE Labs