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

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Message-ID: <AANLkTi=uef63-mHHgHFU14H_Rhytcyc2p34Av6Ms6n3D@mail.gmail.com>
Date:	Thu, 31 Mar 2011 08:53:26 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Dave Jones <davej@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: excessive kworker activity when idle. (was Re: vma corruption in
 today's -git)

And with your fixed trinity thing, I can now do this:

On Wed, Mar 30, 2011 at 9:08 PM, Dave Jones <davej@...hat.com> wrote:
>
> git clone git://git.codemonkey.org.uk/trinity
> cd trinity ; make
> ./trinity --mode=random -i
>
> let it run for a while, then kill it.   kworker should then go nuts.

I really thought "hey, that reproduced it", because "top" did indeed
show kworker going nuts after a while. And perf did show it doing all
that

                   |          queue_work
                   |          schedule_work
                   |          flush_to_ldisc

that looks like the re-scheduling.

But when I killed trinity, kworker immediately calmed down too.

Which I'd actually expect, since any tty it is using (and making cause
problem) should calm down when it's closed - even if it was stuck
before.

But maybe I haven't triggered just the right condition to actually get
it into some really infinite case.

Regardless, I'll put my money where my mouth is, and try to remove the
crazy re-flush thing.

                                         Linus
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