From mboxrd@z Thu Jan 1 00:00:00 1970 From: Corey Minyard Subject: Re: [PATCH][RT] x86: Fix an RT MCE crash Date: Thu, 30 Jun 2016 09:49:19 -0500 Message-ID: <5775316F.2020102@acm.org> References: <1467293089-27656-1-git-send-email-minyard@acm.org> <20160630094301.22d32ec1@gandalf.local.home> Reply-To: minyard@acm.org Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-rt-users@vger.kernel.org, Corey Minyard To: Steven Rostedt Return-path: Received: from mail-oi0-f68.google.com ([209.85.218.68]:35616 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932116AbcF3Ot1 (ORCPT ); Thu, 30 Jun 2016 10:49:27 -0400 Received: by mail-oi0-f68.google.com with SMTP id d132so7819349oig.2 for ; Thu, 30 Jun 2016 07:49:22 -0700 (PDT) In-Reply-To: <20160630094301.22d32ec1@gandalf.local.home> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 06/30/2016 08:43 AM, Steven Rostedt wrote: > On Thu, 30 Jun 2016 08:24:49 -0500 > minyard@acm.org wrote: > >> From: Corey Minyard >> >> On some x86 systems an MCE interrupt would come in before the kernel >> was ready for it. Looking at the latest RT code, it has similar >> (but not quite the same) code, except it adds a bool that tells if >> MCE handling is initialized. Add the same bool for older versions. >> >> Signed-off-by: Corey Minyard >> --- >> arch/x86/kernel/cpu/mcheck/mce.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> We noticed this issue on a new Broadwell system when we booted RT >> on it. This patch is for 3.10, I'm not sure if it applies to >> other kernel versions. > Do you mean other 'older' versions? and that this works with the > versions after 3.10 without this patch? I haven't look at supported kernel versions besides 3.10 and 4.4. The fix was from the 4.4 version of this code. This patch fixes v3.10-rt; I can look at finding which other versions need this. I was planning to do this, but I wanted to get the patch out for comments first. -corey > -- Steve > >> diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c >> index aaf4b9b..7125584 100644 >> --- a/arch/x86/kernel/cpu/mcheck/mce.c >> +++ b/arch/x86/kernel/cpu/mcheck/mce.c >> @@ -1365,6 +1365,7 @@ static void __mce_notify_work(void) >> } >> >> #ifdef CONFIG_PREEMPT_RT_FULL >> +static bool notify_work_ready __read_mostly; >> struct task_struct *mce_notify_helper; >> >> static int mce_notify_helper_thread(void *unused) >> @@ -1386,12 +1387,14 @@ static int mce_notify_work_init(void) >> if (!mce_notify_helper) >> return -ENOMEM; >> >> + notify_work_ready = true; >> return 0; >> } >> >> static void mce_notify_work(void) >> { >> - wake_up_process(mce_notify_helper); >> + if (notify_work_ready) >> + wake_up_process(mce_notify_helper); >> } >> #else >> static void mce_notify_work(void)