Lengthy output of sysrq-w may take a lot of time on slow serial console. Currently we reset NMI-watchdog on the current CPU to avoid spurious lockup messages. Sometimes this doesn't work since softlockup watchdog might trigger on another CPU which is waiting for an IPI to proceed. We reset softlockup watchdogs on all CPUs, but we do this only after listing all tasks, and this may be too late on a busy system. So, reset watchdogs CPUs earlier, in for_each_process_thread() loop.
Unified · Split
| @@ -5147,14 +5147,16 @@ void show_state_filter(unsigned long state_filter) · 5146 unmodified lines | ||
| 5147 | 5147 | /* |
| 5148 | 5148 | * reset the NMI-timeout, listing all files on a slow |
| 5149 | 5149 | * console might take a lot of time: |
| 5150 | + * Also, reset softlockup watchdogs on all CPUs, because | |
| 5151 | + * another CPU might be blocked waiting for us to process | |
| 5152 | + * an IPI. | |
| 5150 | 5153 | */ |
| 5151 | 5154 | touch_nmi_watchdog(); |
| 5155 | + touch_all_softlockup_watchdogs(); | |
| 5152 | 5156 | if (!state_filter || (p->state & state_filter)) |
| 5153 | 5157 | sched_show_task(p); |
| 5154 | 5158 | } |
| 5155 | 5159 | |
| 5156 | − touch_all_softlockup_watchdogs(); | |
| 5157 | − | |
| 5158 | 5160 | #ifdef CONFIG_SCHED_DEBUG |
| 5159 | 5161 | if (!state_filter) |
| 5160 | 5162 | sysrq_sched_debug_show(); |