linux-kernel - [patch 2/2] sched/debug: Remove need

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <eeaed106-cb10-3113-030b-ee23ab3ad0c8@google.com>
Date: Mon, 6 Jan 2025 12:39:22 -0800 (PST)
From: David Rientjes <rientjes@...gle.com>
To: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, 
    Juri Lelli <juri.lelli@...hat.com>, 
    Vincent Guittot <vincent.guittot@...aro.org>
cc: Dietmar Eggemann <dietmar.eggemann@....com>, 
    Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, 
    Mel Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>, 
    linux-kernel@...r.kernel.org
Subject: [patch 2/2] sched/debug: Remove need_resched ratelimiting for
 warnings

The need_resched warnings are controlled by two tunables in debugfs:
 - latency_warn_ms
 - latency_warn_once

By default, latency_warn_once is enabled.  Thus, a need_resched warning
is only emitted once per boot.

If the user configures this to not be the case and changes the default,
then allow the user to also control the threshold through latency_warn_ms
that these warnings trigger.  Do not impose our own ratelimiting on top
that may make it appear like there are no cases where need_resched is set
for longer than the threshold.

Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 kernel/sched/debug.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1293,11 +1293,6 @@ void proc_sched_set_task(struct task_struct *p)
 
 void resched_latency_warn(int cpu, u64 latency)
 {
-	static DEFINE_RATELIMIT_STATE(latency_check_ratelimit, 60 * 60 * HZ, 1);
-
-	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();