linux-kernel - Re: [PATCH v2] sched/core: add forced idle accounting for cgroups

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Date:   Mon, 23 May 2022 14:27:48 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     kbuild@...ts.01.org, Josh Don <joshdon@...gle.com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Tejun Heo <tj@...nel.org>
Cc:     lkp@...el.com, kbuild-all@...ts.01.org,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <vschneid@...hat.com>,
        linux-kernel@...r.kernel.org,
        Cruz Zhao <CruzZhao@...ux.alibaba.com>,
        Josh Don <joshdon@...gle.com>
Subject: Re: [PATCH v2] sched/core: add forced idle accounting for cgroups

Hi Josh,

url:    https://github.com/intel-lab-lkp/linux/commits/Josh-Don/sched-core-add-forced-idle-accounting-for-cgroups/20220521-075311
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-next
config: x86_64-randconfig-m001 (https://download.01.org/0day-ci/archive/20220521/202205211525.XlF6P8dM-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-1) 11.3.0

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>

smatch warnings:
kernel/cgroup/rstat.c:489 cgroup_base_stat_cputime_show() error: uninitialized symbol 'forceidle_time'.

vim +/forceidle_time +489 kernel/cgroup/rstat.c

d4ff749b5e0f1e kernel/cgroup/rstat.c Tejun Heo    2018-04-26  460  void cgroup_base_stat_cputime_show(struct seq_file *seq)
041cd640b2f3c5 kernel/cgroup/stat.c  Tejun Heo    2017-09-25  461  {
041cd640b2f3c5 kernel/cgroup/stat.c  Tejun Heo    2017-09-25  462  	struct cgroup *cgrp = seq_css(seq)->cgroup;
041cd640b2f3c5 kernel/cgroup/stat.c  Tejun Heo    2017-09-25  463  	u64 usage, utime, stime;
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  464  	struct cgroup_base_stat bstat;
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  465  	u64 __maybe_unused forceidle_time;
041cd640b2f3c5 kernel/cgroup/stat.c  Tejun Heo    2017-09-25  466  
936f2a70f2077f kernel/cgroup/rstat.c Boris Burkov 2020-05-27  467  	if (cgroup_parent(cgrp)) {
6162cef0f741c7 kernel/cgroup/rstat.c Tejun Heo    2018-04-26  468  		cgroup_rstat_flush_hold(cgrp);
d4ff749b5e0f1e kernel/cgroup/rstat.c Tejun Heo    2018-04-26  469  		usage = cgrp->bstat.cputime.sum_exec_runtime;
936f2a70f2077f kernel/cgroup/rstat.c Boris Burkov 2020-05-27  470  		cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
936f2a70f2077f kernel/cgroup/rstat.c Boris Burkov 2020-05-27  471  			       &utime, &stime);
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  472  #ifdef CONFIG_SCHED_CORE
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  473  		forceidle_time = cgrp->bstat.forceidle_sum;
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  474  #endif
6162cef0f741c7 kernel/cgroup/rstat.c Tejun Heo    2018-04-26  475  		cgroup_rstat_flush_release();
936f2a70f2077f kernel/cgroup/rstat.c Boris Burkov 2020-05-27  476  	} else {
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  477  		root_cgroup_cputime(&bstat);
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  478  		usage = bstat.cputime.sum_exec_runtime;
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  479  		utime = bstat.cputime.utime;
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  480  		stime = bstat.cputime.stime;
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  481  #ifdef CONFIG_SCHED_CORE
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  482  		forceidle_time = bstat.forceidle_sum;
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  483  #endif
936f2a70f2077f kernel/cgroup/rstat.c Boris Burkov 2020-05-27  484  	}
041cd640b2f3c5 kernel/cgroup/stat.c  Tejun Heo    2017-09-25  485  
041cd640b2f3c5 kernel/cgroup/stat.c  Tejun Heo    2017-09-25  486  	do_div(usage, NSEC_PER_USEC);
041cd640b2f3c5 kernel/cgroup/stat.c  Tejun Heo    2017-09-25  487  	do_div(utime, NSEC_PER_USEC);
041cd640b2f3c5 kernel/cgroup/stat.c  Tejun Heo    2017-09-25  488  	do_div(stime, NSEC_PER_USEC);
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20 @489  	do_div(forceidle_time, NSEC_PER_USEC);

I think this will cause MEMSan warnings at run time.

041cd640b2f3c5 kernel/cgroup/stat.c  Tejun Heo    2017-09-25  490  
d41bf8c9deaed1 kernel/cgroup/stat.c  Tejun Heo    2017-10-23  491  	seq_printf(seq, "usage_usec %llu\n"
d41bf8c9deaed1 kernel/cgroup/stat.c  Tejun Heo    2017-10-23  492  		   "user_usec %llu\n"
d41bf8c9deaed1 kernel/cgroup/stat.c  Tejun Heo    2017-10-23  493  		   "system_usec %llu\n",
d41bf8c9deaed1 kernel/cgroup/stat.c  Tejun Heo    2017-10-23  494  		   usage, utime, stime);
0575a42c9f10cd kernel/cgroup/rstat.c Josh Don     2022-05-20  495  

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