From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id C29418D0039 for ; Sun, 13 Feb 2011 20:21:54 -0500 (EST) Received: from m4.gw.fujitsu.co.jp (unknown [10.0.50.74]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 5BB2C3EE0D7 for ; Mon, 14 Feb 2011 10:21:51 +0900 (JST) Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 388D945DE50 for ; Mon, 14 Feb 2011 10:21:51 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 1473845DE4D for ; Mon, 14 Feb 2011 10:21:51 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id C3C77EF8006 for ; Mon, 14 Feb 2011 10:21:50 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 6A37AEF8001 for ; Mon, 14 Feb 2011 10:21:50 +0900 (JST) Message-ID: <4D588379.4050209@jp.fujitsu.com> Date: Mon, 14 Feb 2011 10:20:57 +0900 From: Hidetoshi Seto MIME-Version: 1.0 Subject: Re: [RFC][PATCH v2] Controlling kexec behaviour when hardware error happened. References: <5C4C569E8A4B9B42A84A977CF070A35B2C1494DBE0@USINDEVS01.corp.hds.com> <4D53A3AA.5050908@jp.fujitsu.com> <20110210091408.GA10553@liondog.tnic> In-Reply-To: <20110210091408.GA10553@liondog.tnic> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Borislav Petkov , Seiji Aguchi , "hpa@zytor.com" , "andi@firstfloor.org" , "ebiederm@xmission.com" , "gregkh@suse.de" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "x86@kernel.org" , "dle-develop@lists.sourceforge.net" , "amwang@redhat.com" , Satoru Moriya (2011/02/10 18:14), Borislav Petkov wrote: > On Thu, Feb 10, 2011 at 05:36:58PM +0900, Hidetoshi Seto wrote: >> (2011/02/10 1:35), Seiji Aguchi wrote: > > [..] > >>> diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c >>> index d916183..e76b47b 100644 >>> --- a/arch/x86/kernel/cpu/mcheck/mce.c >>> +++ b/arch/x86/kernel/cpu/mcheck/mce.c >>> @@ -944,6 +944,8 @@ void do_machine_check(struct pt_regs *regs, long error_code) >>> >>> percpu_inc(mce_exception_count); >>> >>> + hwerr_flag = 1; >>> + >>> if (notify_die(DIE_NMI, "machine check", regs, error_code, >>> 18, SIGKILL) == NOTIFY_STOP) >>> goto out; >> >> Now x86 supports some recoverable machine check, so setting >> flag here will prevent running kexec on systems that have >> encountered such recoverable machine check and recovered. >> >> I think mce_panic() is proper place to set this flag "hwerr_flag". > > I agree, in that case it is unsafe to run kexec only after the error > cannot be recovered by software. > > Also, hwerr_flag is really a bad naming choice, how about > "hwerr_unrecoverable" or "hw_compromised" or "recovery_futile" or > "hw_incurable" or simply say what happened: "pcc" = processor context > corrupt (and a reliable restarting might not be possible). This could be > used by others too, besides kexec. Or how about something like hwerr_panic() to clear that the panic is requested due to hardware error. Anyway, Aguchi-san, please note that we should not turn off kexec before encountering fatal hardware error and before printing/transmitting enough hardware error log to out of this system. > > [..] > >>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 0207c2f..0178f47 100644 >>> --- a/mm/memory-failure.c >>> +++ b/mm/memory-failure.c >>> @@ -994,6 +994,8 @@ int __memory_failure(unsigned long pfn, int trapno, int flags) >>> int res; >>> unsigned int nr_pages; >>> >>> + hwerr_flag = 1; >>> + >>> if (!sysctl_memory_failure_recovery) >>> panic("Memory failure from trap %d on page %lx", trapno, pfn); >>> >> >> For similar reason, setting flag here is not good for >> systems working after isolating some poisoned memory page. >> >> Why not: >> if (!sysctl_memory_failure_recovery) { >> hwerr_flag = 1; >> panic("Memory failure from trap %d on page %lx", trapno, pfn); >> } > > Why do we need that in memory-failure.c at all? I mean, when we consume > the UC, we'll end up in mce_panic() anyway. One possible answer is that memory-failure.c is not x86 specific. Thanks, H.Seto -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org