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

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Message-ID: <20110331154941.GA32045@redhat.com>
Date:	Thu, 31 Mar 2011 11:49:42 -0400
From:	Dave Jones <davej@...hat.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	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 08:25:36AM -0700, Linus Torvalds wrote:
 > 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.

That's a recent change though, and I first saw this back in November.

	Dave

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