sched/debug: Change need_resched warnings to pr_err

need_resched warnings, if enabled, are treated as WARNINGs.  If
kernel.panic_on_warn is enabled, then this causes a kernel panic.

It's highly unlikely that a panic is desired for these warnings, only a
stack trace is normally required to debug and resolve.

Thus, switch need_resched warnings to simply be a printk with an
associated stack trace so they are no longer in scope for panic_on_warn.

Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Acked-by: Josh Don <joshdon@google.com>
Link: https://lkml.kernel.org/r/e8d52023-5291-26bd-5299-8bb9eb604929@google.com

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 5e8e84a2bcb1b23f2754ba5a532d826b79716606..fd7e852207157202d9ceaa522f8a6137b24120c8 100644 (file)
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1292,8 +1292,10 @@ void resched_latency_warn(int cpu, u64 latency)
 {
        static DEFINE_RATELIMIT_STATE(latency_check_ratelimit, 60 * 60 * HZ, 1);
 
-       WARN(__ratelimit(&latency_check_ratelimit),
-            "sched: CPU %d need_resched set for > %llu ns (%d ticks) "
-            "without schedule\n",
-            cpu, latency, cpu_rq(cpu)->ticks_without_resched);
+       if (likely(!__ratelimit(&latency_check_ratelimit)))
+               return;
+
+       pr_err("sched: CPU %d need_resched set for > %llu ns (%d ticks) without schedule\n",
+              cpu, latency, cpu_rq(cpu)->ticks_without_resched);
+       dump_stack();
 }