This is a note to let you know that I've just added the patch titled
x86/mce: Ensure offline CPUs don't participate in rendezvous process
to the 4.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-mce-ensure-offline-cpus-don-t-participate-in-rendezvous-process.patch
and it can be found in the queue-4.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d90167a941f62860f35eb960e1012aa2d30e7e94 Mon Sep 17 00:00:00 2001
From: Ashok Raj <ashok.raj@xxxxxxxxx>
Date: Thu, 10 Dec 2015 11:12:26 +0100
Subject: x86/mce: Ensure offline CPUs don't participate in rendezvous process
From: Ashok Raj <ashok.raj@xxxxxxxxx>
commit d90167a941f62860f35eb960e1012aa2d30e7e94 upstream.
Intel's MCA implementation broadcasts MCEs to all CPUs on the
node. This poses a problem for offlined CPUs which cannot
participate in the rendezvous process:
Kernel panic - not syncing: Timeout: Not all CPUs entered broadcast exception handler
Kernel Offset: disabled
Rebooting in 100 seconds..
More specifically, Linux does a soft offline of a CPU when
writing a 0 to /sys/devices/system/cpu/cpuX/online, which
doesn't prevent the #MC exception from being broadcasted to that
CPU.
Ensure that offline CPUs don't participate in the MCE rendezvous
and clear the RIP valid status bit so that a second MCE won't
cause a shutdown.
Without the patch, mce_start() will increment mce_callin and
wait for all CPUs. Offlined CPUs should avoid participating in
the rendezvous process altogether.
Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
[ Massage commit message. ]
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-edac <linux-edac@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1449742346-21470-2-git-send-email-bp@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/mcheck/mce.c | 11 +++++++++++
1 file changed, 11 insertions(+)
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -999,6 +999,17 @@ void do_machine_check(struct pt_regs *re
int flags = MF_ACTION_REQUIRED;
int lmce = 0;
+ /* If this CPU is offline, just bail out. */
+ if (cpu_is_offline(smp_processor_id())) {
+ u64 mcgstatus;
+
+ mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
+ if (mcgstatus & MCG_STATUS_RIPV) {
+ mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
+ return;
+ }
+ }
+
ist_enter(regs);
this_cpu_inc(mce_exception_count);
Patches currently in stable-queue which might be from ashok.raj@xxxxxxxxx are
queue-4.3/x86-mce-ensure-offline-cpus-don-t-participate-in-rendezvous-process.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html