linux-kernel - Re: 4.8.8 kernel trigger OOM killer repeatedly when I have lots of RAM that should be free

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Message-ID: <20161130182144.xhnmgpsyyv423pqw@merlins.org>
Date:   Wed, 30 Nov 2016 10:21:44 -0800
From:   Marc MERLIN <marc@...lins.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Kent Overstreet <kent.overstreet@...il.com>,
        Tejun Heo <tj@...nel.org>, Jens Axboe <axboe@...com>,
        Michal Hocko <mhocko@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: 4.8.8 kernel trigger OOM killer repeatedly when I have lots of
 RAM that should be free

On Wed, Nov 30, 2016 at 10:14:50AM -0800, Linus Torvalds wrote:
> Anyway, none of this seems new per se. I'm adding Kent and Jens to the
> cc (Tejun already was), in the hope that maybe they have some idea how
> to control the nasty worst-case behavior wrt workqueue lockup (it's
> not really a "lockup", it looks like it's just hundreds of workqueues
> all waiting for IO to complete and much too deep IO queues).
 
I'll take your word for it, all I got in the end was
Kernel panic - not syncing: Hard LOCKUP
and the system stone dead when I woke up hours later.

> And I think your NMI watchdog then turns the "system is no longer
> responsive" into an actual kernel panic.

Ah, I see.

Thanks for the reply, and sorry for bringing in that separate thread
from the btrfs mailing list, which effectively was a suggestion similar
to what you're saying here too.

Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/                         | PGP 1024R/763BE901