[3.16.y-ckt stable] Patch "sparc: Touch NMI watchdog when walking cpus and calling printk" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Tue Mar 24 15:35:30 UTC 2015

This is a note to let you know that I have just added a patch titled

    sparc: Touch NMI watchdog when walking cpus and calling printk

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:


This patch is scheduled to be released in version 3.16.7-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see



>From 1d1d2f24fd2de81c284d37fa178dff11612f5625 Mon Sep 17 00:00:00 2001
From: David Ahern <david.ahern at oracle.com>
Date: Thu, 19 Mar 2015 16:06:53 -0400
Subject: sparc: Touch NMI watchdog when walking cpus and calling printk

commit 31aaa98c248da766ece922bbbe8cc78cfd0bc920 upstream.

With the increase in number of CPUs calls to functions that dump
output to console (e.g., arch_trigger_all_cpu_backtrace) can take
a long time to complete. If IRQs are disabled eventually the NMI
watchdog kicks in and creates more havoc. Avoid by telling the NMI
watchdog everything is ok.

Signed-off-by: David Ahern <david.ahern at oracle.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 arch/sparc/kernel/process_64.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 0be7bf978cb1..46a59643bb1c 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -287,6 +287,8 @@ void arch_trigger_all_cpu_backtrace(bool include_self)
 			printk("             TPC[%lx] O7[%lx] I7[%lx] RPC[%lx]\n",
 			       gp->tpc, gp->o7, gp->i7, gp->rpc);
+		touch_nmi_watchdog();

 	memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));
@@ -362,6 +364,8 @@ static void pmu_snapshot_all_cpus(void)
 		       (cpu == this_cpu ? '*' : ' '), cpu,
 		       pp->pcr[0], pp->pcr[1], pp->pcr[2], pp->pcr[3],
 		       pp->pic[0], pp->pic[1], pp->pic[2], pp->pic[3]);
+		touch_nmi_watchdog();

 	memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));

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