linux-kernel - Re: [PATCH] [4/4] x86: MCE: Fix EIPV behaviour with !PCC

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Message-Id: <1240479838.6842.555.camel@yhuang-dev.sh.intel.com>
Date:	Thu, 23 Apr 2009 17:43:58 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	"hpa@...or.com" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"tglx@...utronix.de" <tglx@...utronix.de>
Subject: Re: [PATCH] [4/4] x86: MCE: Fix EIPV behaviour with !PCC

Add some description for the patch, hope that to be more clear.

Best Regards,
Huang Ying
-------------------------------------------------->
Impact: Spec compliance

Tolerant level 0 means: always panic on uncorrected errors, that is,
panic even for recoverable uncorrected errors. This is a useful option
for someone think panic is the better hardware error containment
mechanism than trying to recover.

Current implementation does not comply with the tolerant == 0 spec,
that is, it tries to recover (by killing related processes) for
recoverable uncorrected errors (errors triggered in userspace) when
tolerant == 0. This patch fixes this by going panic for that case.

Signed-off-by: Huang Ying <ying.huang@...el.com>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>

---
 arch/x86/kernel/cpu/mcheck/mce_64.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/mcheck/mce_64.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_64.c
@@ -400,7 +400,7 @@ void do_machine_check(struct pt_regs * r
 		 * force_sig() takes an awful lot of locks and has a slight
 		 * risk of deadlocking.
 		 */
-		if (user_space) {
+		if (user_space && tolerant > 0) {
 			force_sig(SIGBUS, current);
 		} else if (panic_on_oops || tolerant < 2) {
 			mce_panic("Uncorrected machine check",

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