sched/debug: Change need_resched warnings to pr_err

JIRA: https://issues.redhat.com/browse/RHEL-78821

commit 8061b9f
Author: David Rientjes <rientjes@google.com>
Date:   Thu Jan 9 16:24:33 2025 -0800

    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

Signed-off-by: Phil Auld <pauld@redhat.com>

Author: auldp

kernel/sched/debug.c

@@ -1116,8 +1116,10 @@ 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();
 }