From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: Regression in v3.4-rc0 " BUG: soft lockup - CPU#0 stuck for 29s! [migration/0:6]..[] stop_machine_cpu_stop+0x7b/0xf Date: Wed, 21 Mar 2012 23:04:08 -0400 Message-ID: <1332385449-29281-1-git-send-email-konrad.wilk@oracle.com> References: <1332347541.18960.498.camel@twins> Return-path: In-Reply-To: <1332347541.18960.498.camel@twins> Sender: linux-kernel-owner@vger.kernel.org To: peterz@infradead.org, linux-kernel@vger.kernel.org, mingo@elte.hu, rjw@sisk.pl, tglx@linutronix.de Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Wed, Mar 21, 2012 at 05:32:21PM +0100, Peter Zijlstra wrote: > On Wed, 2012-03-21 at 17:30 +0100, Peter Zijlstra wrote: > > On Wed, 2012-03-21 at 16:57 +0100, Peter Zijlstra wrote: > > > On Wed, 2012-03-21 at 11:26 -0400, Konrad Rzeszutek Wilk wrote: > > > > On Tue, Mar 20, 2012 at 07:53:22PM -0400, Konrad Rzeszutek Wilk wrote: > > > > > Seeing this in v3.4-rc0 tree and didn't see that with v3.3: > > > > > > > > Hey Peter, > > > > > > > > Git bisection points this to the fault of > > > > 5fbd036b552f633abb394a319f7c62a5c86a9cd7 " sched: Cleanup cpu_active madness" > > > > > > > > thoughts? (also attaching the .config) > > > > > > Argh.. so when is this? boot? No that's somewhat unexpected. I have one > > > report of funnies during a hotplug bash that I'm looking into, but I > > > haven't actually been able to reproduce that report myself either. > > > > is arch/x86/xen/smp.c:cpu_bringup() missing a call to > > notify_cpu_starting() before doing set_cpu_online()? > > > > Also, shouldn't that also take the ipi_call_lock() around setting the > > cpu online? > > > And before you ask, yes all that should live in generic code... somehow. > This per-arch replication of the cpu hotplug logic is driving me insane. Thanks to Peter, here is the patch that fixes the regression.