(2011/02/10 18:14), Borislav Petkov wrote:

On Thu, Feb 10, 2011 at 05:36:58PM +0900, Hidetoshi Seto wrote:

quoted

(2011/02/10 1:35), Seiji Aguchi wrote:

[..]

quoted

quoted

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.

[..]

quoted

quoted

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

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