linux-kernel - Re: BUG_ON() in workingset_node_shadows

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Message-ID: <20161005210900.GB8116@1wt.eu>
Date:   Wed, 5 Oct 2016 23:09:00 +0200
From:   Willy Tarreau <w@....eu>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Paul Gortmaker <paul.gortmaker@...driver.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Antonio SJ Musumeci <trapexit@...wn.link>,
        Miklos Szeredi <miklos@...redi.hu>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        stable <stable@...r.kernel.org>
Subject: Re: BUG_ON() in workingset_node_shadows_dec() triggers

On Wed, Oct 05, 2016 at 12:18:51PM -0700, Linus Torvalds wrote:
> Quite frankly, I wouldn't do a sed-script pass to actually change
> existing users. I'd just change how the BUG() implementation itself
> works. Not make it a direct WARN_ON(), but perhaps something like
> 
>  - use WARN_ON() with a global rate limiter (we do *not* want BUG
> cascades, but re-enable the warning after a few minutes)

That's interesting, I had exactly this discussion at kernel recipes
last week with someone complaining that when warnings scroll, you
only see the last ones while only the first one is useful. I guess
in most situations we don't even need a rate limiter, just print a
single dump and wait 2 minutes or so for the person in front of the
screen to have the time to take a photo.

>  - have some kernel command line option for the server people to allow
> them to just force a reboot for it

Good point for not doing the sed.

> Hmm?
> 
> Anybody want to play with it?

Many people will be much more efficient than me at doing it and even
testing it so I won't volunteer here.

Willy