linux-kernel - Re: [PATCH 1/7] sched: warn for high latency with TIF_NEED_RESCHED

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Message-ID: <202410131715.HYC3WK5i-lkp@intel.com>
Date: Sun, 13 Oct 2024 17:44:24 +0800
From: kernel test robot <lkp@...el.com>
To: Ankur Arora <ankur.a.arora@...cle.com>, linux-kernel@...r.kernel.org
Cc: oe-kbuild-all@...ts.linux.dev, peterz@...radead.org, tglx@...utronix.de,
	paulmck@...nel.org, mingo@...nel.org, bigeasy@...utronix.de,
	juri.lelli@...hat.com, vincent.guittot@...aro.org,
	dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
	mgorman@...e.de, vschneid@...hat.com, frederic@...nel.org,
	ankur.a.arora@...cle.com, efault@....de
Subject: Re: [PATCH 1/7] sched: warn for high latency with
 TIF_NEED_RESCHED_LAZY

Hi Ankur,

kernel test robot noticed the following build errors:

[auto build test ERROR on paulmck-rcu/dev]
[also build test ERROR on powerpc/next powerpc/fixes tip/sched/core linus/master v6.12-rc2 next-20241011]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Ankur-Arora/sched-warn-for-high-latency-with-TIF_NEED_RESCHED_LAZY/20241010-005819
base:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev
patch link:    https://lore.kernel.org/r/20241009165411.3426937-2-ankur.a.arora%40oracle.com
patch subject: [PATCH 1/7] sched: warn for high latency with TIF_NEED_RESCHED_LAZY
config: x86_64-rhel-8.3 (https://download.01.org/0day-ci/archive/20241013/202410131715.HYC3WK5i-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241013/202410131715.HYC3WK5i-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410131715.HYC3WK5i-lkp@intel.com/

All errors (new ones prefixed by >>):

   kernel/sched/core.c: In function 'cpu_resched_latency':
>> kernel/sched/core.c:5528:34: error: implicit declaration of function 'tif_need_resched_lazy'; did you mean 'tif_need_resched'? [-Werror=implicit-function-declaration]
    5528 |         if ((!need_resched() && !tif_need_resched_lazy()) || !latency_warn_ms)
         |                                  ^~~~~~~~~~~~~~~~~~~~~
         |                                  tif_need_resched
   cc1: some warnings being treated as errors


vim +5528 kernel/sched/core.c

  5517	
  5518	#ifdef CONFIG_SCHED_DEBUG
  5519	static u64 cpu_resched_latency(struct rq *rq)
  5520	{
  5521		int latency_warn_ms = READ_ONCE(sysctl_resched_latency_warn_ms);
  5522		u64 resched_latency, now = rq_clock(rq);
  5523		static bool warned_once;
  5524	
  5525		if (sysctl_resched_latency_warn_once && warned_once)
  5526			return 0;
  5527	
> 5528		if ((!need_resched() && !tif_need_resched_lazy()) || !latency_warn_ms)
  5529			return 0;
  5530	
  5531		if (system_state == SYSTEM_BOOTING)
  5532			return 0;
  5533	
  5534		if (!rq->last_seen_need_resched_ns) {
  5535			rq->last_seen_need_resched_ns = now;
  5536			rq->ticks_without_resched = 0;
  5537			return 0;
  5538		}
  5539	
  5540		rq->ticks_without_resched++;
  5541		resched_latency = now - rq->last_seen_need_resched_ns;
  5542		if (resched_latency <= latency_warn_ms * NSEC_PER_MSEC)
  5543			return 0;
  5544	
  5545		warned_once = true;
  5546	
  5547		return resched_latency;
  5548	}
  5549	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki