linux-kernel - Re: [PATCH v2] x86/mce: Distirbute the clear operation of mces_seen to Per-CPU rather than only monarch CPU

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Message-ID: <20140523091041.GA21332@pd.tnic>
Date:	Fri, 23 May 2014 11:10:41 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	"Luck, Tony" <tony.luck@...el.com>
Cc:	Chen Yucong <slaoub@...il.com>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	"Huang, Ying" <ying.huang@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>
Subject: Re: [PATCH v2] x86/mce: Distirbute the clear operation of mces_seen
 to Per-CPU rather than only monarch CPU

On Fri, May 23, 2014 at 09:32:19AM +0800, Chen Yucong wrote:
> ...if we reach a timeout, there is very little
> chance for recovering. Thought. the probability for this situation to
> happen is very slight, it's not impossible. Indeed, it's hard to know
> the precise causes for timeout.

Ok, enough talking, let's close that hole and get on with our lives:

---
From: Borislav Petkov <bp@...e.de>
Date: Fri, 23 May 2014 11:06:35 +0200
Subject: [PATCH] mce: Panic when a core has reached a timeout

There is very little and maybe practically nothing we can do to recover
from a system where at least one core has reached a timeout during the
whole monarch cores gathering. So panic when that happens.

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/cpu/mcheck/mce.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index bfde4871848f..529ccc488f5a 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -704,8 +704,7 @@ static int mce_timed_out(u64 *t)
 	if (!mca_cfg.monarch_timeout)
 		goto out;
 	if ((s64)*t < SPINUNIT) {
-		/* CHECKME: Make panic default for 1 too? */
-		if (mca_cfg.tolerant < 1)
+		if (mca_cfg.tolerant <= 1)
 			mce_panic("Timeout synchronizing machine check over CPUs",
 				  NULL, NULL);
 		cpu_missing = 1;
-- 
1.9.0

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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