linux-kernel - Re: [regression -next0117] What is kcompactd and why is he eating 100% of my cpu?

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Message-ID: <14875.1548810399@turing-police.cc.vt.edu>
Date:   Tue, 29 Jan 2019 20:06:39 -0500
From:   valdis.kletnieks@...edu
To:     Jan Kara <jack@...e.cz>
cc:     Pavel Machek <pavel@....cz>,
        Mel Gorman <mgorman@...hsingularity.net>,
        kernel list <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...l.org>, vbabka@...e.cz,
        aarcange@...hat.com, rientjes@...gle.com, mhocko@...nel.org,
        zi.yan@...rutgers.edu, hannes@...xchg.org
Subject: Re: [regression -next0117] What is kcompactd and why is he eating 100% of my cpu?

On Mon, 28 Jan 2019 10:16:27 +0100, Jan Kara said:

> So my buffer_migrate_page_norefs() is certainly buggy in its current
> incarnation (as a result block device page cache is not migratable at all).
> I've sent Andrew a patch over week ago but so far it got ignored. The patch
> is attached, can you give it a try whether it changes something for you?
> Thanks!

Been running with the patch for about 24 hours, haven't seen kcompactd
misbehave.  I even fired up a Chrome with a lot of tabs open, a Firefox, and a
kernel build, intentionally drove the system into swapping, and kcompactd
didn't make it into the top 10 on 'top'.

I'm willing to say put a "tested-by:" on that one,  it looks fixed from here.
If there's any remaining bugs, they're ones I can't seem to trigger...