From ed5e9462f6617a85945353abe5c4b94a81ee01a1 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 30 Aug 2018 17:05:19 +0200 Subject: [PATCH] tick/nohz: Prevent bogus softirq pending warning Commit 0a0e0829f990 ("nohz: Fix missing tick reprogram when interrupting an inline softirq") got backported to stable trees and now causes the NOHZ softirq pending warning to trigger. It's not an upstream issue as the NOHZ update logic has been changed there. The problem is when a softirq disabled section gets interrupted and on return from interrupt the tick/nohz state is evaluated, which then can observe pending soft interrupts. These soft interrupts are legitimately pending because they cannot be processed as long as soft interrupts are disabled and the interrupted code will correctly process them when soft interrupts are reenabled. Add a check for softirqs disabled to the pending check to prevent the warning. Reported-by: Grygorii Strashko Reported-by: John Crispin Signed-off-by: Thomas Gleixner Tested-by: Grygorii Strashko Tested-by: John Crispin Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Anna-Maria Gleixner Cc: stable@vger.kernel.org Fixes: 2d898915ccf4838c ("nohz: Fix missing tick reprogram when interrupting an inline softirq") Acked-by: Frederic Weisbecker Tested-by: Geert Uytterhoeven --- kernel/time/tick-sched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index ea3c062e7e1c..a8fa0a896b78 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -908,7 +908,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) if (unlikely(local_softirq_pending() && cpu_online(cpu))) { static int ratelimit; - if (ratelimit < 10 && + if (ratelimit < 10 && !in_softirq() && (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { pr_warn("NOHZ: local_softirq_pending %02x\n", (unsigned int) local_softirq_pending()); -- 2.20.1