From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [patch 1/4] Ignore stolen time in the softlockup watchdog Date: Tue, 24 Apr 2007 13:33:59 -0700 Message-ID: <20070424133359.f18bce78.akpm@linux-foundation.org> References: <20070327214919.800272641@goop.org> <20070327215827.871954359@goop.org> <20070423234910.50149faf.akpm@linux-foundation.org> <462E43A7.1050001@goop.org> <20070424105738.e0ce36a9.akpm@linux-foundation.org> <462E4969.6070802@goop.org> <20070424113222.ed2e1314.akpm@linux-foundation.org> <462E61F1.7060403@goop.org> <462E6778.7070305@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <462E6778.7070305@goop.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Jeremy Fitzhardinge Cc: Prarit Bhargava , Rick Lindsley , Thomas Gleixner , john stultz , Linux Kernel , Eric Dumazet , virtualization@lists.osdl.org, Chris Lalancette , Mackerras , Martin Schwidefsky , Paul@smtp2.linux-foundation.org, Ingo Molnar List-Id: virtualization@lists.linuxfoundation.org On Tue, 24 Apr 2007 13:24:24 -0700 Jeremy Fitzhardinge wrote: > Jeremy Fitzhardinge wrote: > > Andrew Morton wrote: > > > >> Well, it _is_ mysterious. > >> > >> Did you try to locate the code which failed? I got lost in macros and > >> include files, and gave up very very easily. Stop hiding, Ingo. > >> > >> > > > > OK, I've managed to reproduce it. Removing the local_irq_save/restore > > from sched_clock() makes it go away, as I'd expect (otherwise it would > > really be magic). But given that it never seems to touch the softlockup > > during testing, I have no idea what difference it makes... > > And sched_clock's use of local_irq_save/restore appears to be absolutely > correct, so I think it must be triggering a bug in either the self-tests > or lockdep itself. It's weird. And I don't think the locking selftest code calls sched_clock() (or any other time-related thing) at all, does it? > The only way I could actually extract the test code itself was to run > the whole thing through cpp+indent, but it doesn't shed much light. > > It's also not clear to me if there are 6 independent failures, or if > they're a cascade. Oh well. I'll restore the patches and when people hit problems we can blame Ingo!