linux-kernel - Re: excessive kworker activity when idle. (was Re: vma corruption in today's -git)

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Message-ID: <AANLkTimAGbzYe7PNG1xhjsA12zErpRasTso711cq8UHq@mail.gmail.com>
Date:	Thu, 31 Mar 2011 08:25:36 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Dave Jones <davej@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Tejun Heo <tj@...nel.org>
Subject: Re: excessive kworker activity when idle. (was Re: vma corruption in
 today's -git)

On Thu, Mar 31, 2011 at 8:03 AM, Dave Jones <davej@...hat.com> wrote:
> On Thu, Mar 31, 2011 at 10:58:50AM -0400, Dave Jones wrote:
>
> bah I missed a level. which seems to be the smoking gun.
> something in the tty layer seems to have gone nuts.

Ahhah. That is indeed the smoking gun.

I bet it's an old problem where something causes some stupid tty
ping-pong behaviour, and now it has become a high-CPU thing triggered
by commit f23eb2b2b285 ("tty: stop using "delayed_work" in the tty
layer").

Before that commit, if the tty layer got somehow confused, it would
always delay for a timer tick in between doing nothing. Now it will go
pretty much full blast. Which explains your CPU being hot.

                        Linus
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