From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Jin Date: Tue, 04 Jan 2011 00:34:00 +0000 Subject: Re: [Xen-devel] Re: [patch] xenfb: fix xenfb suspend/resume race Message-Id: <4D226AF8.1010102@oracle.com> List-Id: References: <20101230125616.GA31537@joejin-pc.cn.oracle.com> <20101230164051.GC24313@dumpdata.com> <4D1D2A2D.80206@oracle.com> <20110103163418.GA14102@dumpdata.com> In-Reply-To: <20110103163418.GA14102@dumpdata.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Konrad Rzeszutek Wilk Cc: jeremy@goop.org, xen-devel@lists.xensource.com, ian.campbell@citrix.com, gurudas.pai@oracle.com, guru.anbalagane@oracle.com, greg.marsden@oracle.com, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, Andrew Morton On 01/04/11 00:34, Konrad Rzeszutek Wilk wrote: >>> I am unclear from your description whether the patch fixes >>> the problem (I would presume so). Or does it take a long time >>> to hit this race? >>> >> Yes, more than 100 migrations. we hit this issue around 3 times. > > OK, so you are still trying to find the culprit. > > Did you look at this patch from Ian: > > https://patchwork.kernel.org/patch/403192/ We have reproduced the issue with the patch. > > ? >> >> I dumped vmcore when guest crashed, from vmcore everything >> looked good, fb_info, xenfb_info and so on. > > And the event channels are correct? > > .. snip.. >> diff --git a/drivers/xen/events.c b/drivers/xen/events.c >> index ac7b42f..4cfb5e2 100644 >> --- a/drivers/xen/events.c >> +++ b/drivers/xen/events.c >> @@ -175,6 +175,8 @@ static struct irq_info *info_for_irq(unsigned irq) >> >> static unsigned int evtchn_from_irq(unsigned irq) >> { >> + if (unlikely(irq < 0 || irq >= nr_irqs)) >> + return 0; > > You could insert a WARN_ON here to see see if you get this during your > migration process. > > Or use xen_raw_printk in case the guest is hung for good. > Thanks for your advice, will try it.