parisc: Suspend lockup detectors before system halt

Some machines can't power off the machine, so disable the lockup detectors to avoid this watchdog BUG to show up every few seconds:

watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [systemd-shutdow:1]

index b64d7d2..a45a67d 100644
@@ -53,6 +53,7 @@
 #include <linux/uaccess.h>
 #include <linux/rcupdate.h>
 #include <linux/random.h>
+#include <linux/nmi.h>
 
 #include <asm/io.h>
 #include <asm/asm-offsets.h>

@@ -145,6 +146,7 @@ void machine_power_off(void)
 
 	/* prevent soft lockup/stalled CPU messages for endless loop. */
 	rcu_sysrq_start();
+	lockup_detector_suspend();
 	for (;;);
 }
 

I don't think HPPA is the only architecture that has this problem, so isn't there a generic solution? Or: is it time to add one?

Eike

Maybe.
I haven't heard of others yet, probably because most other architectures do power off themselves, so they won't see this problem.

Sure, you are welcome to test, post and discuss patches upstream if you like. It's not a very critical issue, so I can wait with pushing my patch.

Helge

By the way, I still see another lockup once (workqueue lockup) even after this patch. In general it seems most lockup detectors don't unregister themselves in the poweroff/shutdown phase (which might be intentional):

[  123.664431] BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 36s!
[  123.857429] Showing busy workqueues and worker pools:
[  123.917919] workqueue events: flags=0x0
[  123.963830]   pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256                 
[  123.967817]     pending: vmstat_shepherd                                         
[  124.082949] workqueue events_freezable: flags=0x4                                
[  124.139364]   pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256                 
[  124.143350]     pending: pci_pme_list_scan                                       
[  124.260448] workqueue events_power_efficient: flags=0x80
[  124.324059]   pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[  124.328045]     pending: neigh_periodic_work
[  124.447237] workqueue mm_percpu_wq: flags=0x8
[  124.499488]   pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[  124.510543]     pending: vmstat_update
[  124.616432] workqueue mpt_poll_1: flags=0x8
[  124.666595]   pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[  124.673079]     pending: mpt_fault_reset_work

Helge

I wont be able to do anything like that this week (maybe longer), so please go ahead with your patch to get rid of the annoying warning. Cleanups later.

Eike