From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> This patch has been added to the 4.1 stable tree. If you have any objections, please let us know. =============== [ Upstream commit 57675cb976eff977aefb428e68e4e0236d48a9ff ] 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. Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1465474805-14641-1-git-send-email-aryabinin@xxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx> --- kernel/sched/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 3b0f4c0..98e6071 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4568,14 +4568,16 @@ void show_state_filter(unsigned long state_filter) /* * reset the NMI-timeout, listing all files on a slow * console might take a lot of time: + * Also, reset softlockup watchdogs on all CPUs, because + * another CPU might be blocked waiting for us to process + * an IPI. */ touch_nmi_watchdog(); + touch_all_softlockup_watchdogs(); if (!state_filter || (p->state & state_filter)) sched_show_task(p); } - touch_all_softlockup_watchdogs(); - #ifdef CONFIG_SCHED_DEBUG sysrq_sched_debug_show(); #endif -- 2.5.0 -- 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