linux-kernel - [PATCH] x86, MCE: Flesh out when to panic comment

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Date:	Mon, 26 May 2014 12:18:59 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jiri Kosina <jkosina@...e.cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	Steven Rostedt <rostedt@...dmis.org>,
	Andi Kleen <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	"Luck, Tony" <tony.luck@...el.com>
Subject: [PATCH] x86, MCE: Flesh out when to panic comment

On Wed, May 21, 2014 at 03:13:54PM -0700, H. Peter Anvin wrote:
> Seems like a comment would be in order, though.

---
From: Borislav Petkov <bp@...e.de>
Subject: [PATCH] x86, MCE: Flesh out when to panic comment

Recent discussion (link below) showed that it is not really clear what
appropriate recovery actions we're taking when in a machine check
exception. Flesh out the comment which was explaining that with more
detail.

Suggested-by: "H. Peter Anvin" <hpa@...or.com>
Cc: Tony Luck <tony.luck@...el.com>
Link: http://lkml.kernel.org/r/CALCETrXudJ8BkNF_M-r4O40XLN%2BPnZ5TOZw0P7N4kqo3qngzyg@mail.gmail.com
Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/cpu/mcheck/mce.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 68317c80de7f..9f070339b09f 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1151,10 +1151,14 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 		no_way_out = worst >= MCE_PANIC_SEVERITY;
 
 	/*
-	 * At insane "tolerant" levels we take no action. Otherwise
-	 * we only die if we have no other choice. For less serious
-	 * issues we try to recover, or limit damage to the current
-	 * process.
+	 * At insane "tolerant" levels we take no action. Otherwise we only die
+	 * if we have no other choice. Which means, we're definitely going to
+	 * panic on unrecoverable, uncontainable errors which would otherwise
+	 * influence machine state and/or cause any type of corruption. The
+	 * decision what do to is done by mce_severity().
+	 *
+	 * For less serious issues we try to recover, or limit damage to the
+	 * current process.
 	 */
 	if (cfg->tolerant < 3) {
 		if (no_way_out)
-- 
1.9.0

-- 
Regards/Gruss,
    Boris.

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