Re: [RFC PATCH 1/2] sched/topology: Get rid of NUMA overlapping groups

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From: Dan Carpenter <dan.carpenter@oracle.com>
To: kbuild@lists.01.org
Subject: Re: [RFC PATCH 1/2] sched/topology: Get rid of NUMA overlapping groups
Date: Wed, 03 Feb 2021 21:38:40 +0300	[thread overview]
Message-ID: <20210203183840.GY2696@kadam> (raw)
In-Reply-To: <20210203155432.10293-2-valentin.schneider@arm.com>

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Hi Valentin,

url:    https://github.com/0day-ci/linux/commits/Valentin-Schneider/sched-topology-Get-rid-of-overlapping-groups/20210204-000142
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 075a28439d0c8eb6d3c799e1eed24bb9bc7750cd
config: s390-randconfig-m031-20210204 (attached as .config)
compiler: s390-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
kernel/sched/topology.c:1012 find_node_domain() error: uninitialized symbol 'parent'.

vim +/parent +1012 kernel/sched/topology.c

02d81c8f49452e Valentin Schneider   2021-02-03   985  static struct sched_domain *find_node_domain(struct sched_domain *sd)
02d81c8f49452e Valentin Schneider   2021-02-03   986  {
02d81c8f49452e Valentin Schneider   2021-02-03   987  	struct sched_domain *parent;
02d81c8f49452e Valentin Schneider   2021-02-03   988  
02d81c8f49452e Valentin Schneider   2021-02-03   989  	BUG_ON(!(sd->flags & SD_NUMA));
02d81c8f49452e Valentin Schneider   2021-02-03   990  
02d81c8f49452e Valentin Schneider   2021-02-03   991  	/* Get to the level above NODE */
02d81c8f49452e Valentin Schneider   2021-02-03   992  	while (sd && sd->child) {

Presumably this is always true when the function is called so this
warning is a false positive?

02d81c8f49452e Valentin Schneider   2021-02-03   993  		parent = sd;
02d81c8f49452e Valentin Schneider   2021-02-03   994  		sd = sd->child;
02d81c8f49452e Valentin Schneider   2021-02-03   995  
02d81c8f49452e Valentin Schneider   2021-02-03   996  		if (!(sd->flags & SD_NUMA))
02d81c8f49452e Valentin Schneider   2021-02-03   997  			break;
02d81c8f49452e Valentin Schneider   2021-02-03   998  	}
02d81c8f49452e Valentin Schneider   2021-02-03   999  	/*
02d81c8f49452e Valentin Schneider   2021-02-03  1000  	 * We're going to create cross topology level sched_group_capacity
02d81c8f49452e Valentin Schneider   2021-02-03  1001  	 * references. This can only work if the domains resulting from said
02d81c8f49452e Valentin Schneider   2021-02-03  1002  	 * levels won't be degenerated, as we need said sgc to be periodically
02d81c8f49452e Valentin Schneider   2021-02-03  1003  	 * updated: it needs to be attached to the local group of a domain
02d81c8f49452e Valentin Schneider   2021-02-03  1004  	 * that didn't get degenerated.
02d81c8f49452e Valentin Schneider   2021-02-03  1005  	 *
02d81c8f49452e Valentin Schneider   2021-02-03  1006  	 * Of course, groups aren't available yet, so we can't call the usual
02d81c8f49452e Valentin Schneider   2021-02-03  1007  	 * sd_degenerate(). Checking domain spans is the closest we get.
02d81c8f49452e Valentin Schneider   2021-02-03  1008  	 * Start from NODE's parent, and keep going up until we get a domain
02d81c8f49452e Valentin Schneider   2021-02-03  1009  	 * we're sure won't be degenerated.
02d81c8f49452e Valentin Schneider   2021-02-03  1010  	 */
02d81c8f49452e Valentin Schneider   2021-02-03  1011  	while (sd->parent &&
02d81c8f49452e Valentin Schneider   2021-02-03 @1012  	       cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) {
02d81c8f49452e Valentin Schneider   2021-02-03  1013  		sd = parent;
02d81c8f49452e Valentin Schneider   2021-02-03  1014  		parent = sd->parent;
02d81c8f49452e Valentin Schneider   2021-02-03  1015  	}
02d81c8f49452e Valentin Schneider   2021-02-03  1016  
02d81c8f49452e Valentin Schneider   2021-02-03  1017  	return parent;
02d81c8f49452e Valentin Schneider   2021-02-03  1018  }

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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WARNING: multiple messages have this Message-ID (diff)

From: Dan Carpenter <dan.carpenter@oracle.com>
To: kbuild-all@lists.01.org
Subject: Re: [RFC PATCH 1/2] sched/topology: Get rid of NUMA overlapping groups
Date: Wed, 03 Feb 2021 21:38:40 +0300	[thread overview]
Message-ID: <20210203183840.GY2696@kadam> (raw)
In-Reply-To: <20210203155432.10293-2-valentin.schneider@arm.com>

[-- Attachment #1: Type: text/plain, Size: 3771 bytes --]

Hi Valentin,

url:    https://github.com/0day-ci/linux/commits/Valentin-Schneider/sched-topology-Get-rid-of-overlapping-groups/20210204-000142
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 075a28439d0c8eb6d3c799e1eed24bb9bc7750cd
config: s390-randconfig-m031-20210204 (attached as .config)
compiler: s390-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
kernel/sched/topology.c:1012 find_node_domain() error: uninitialized symbol 'parent'.

vim +/parent +1012 kernel/sched/topology.c

02d81c8f49452e Valentin Schneider   2021-02-03   985  static struct sched_domain *find_node_domain(struct sched_domain *sd)
02d81c8f49452e Valentin Schneider   2021-02-03   986  {
02d81c8f49452e Valentin Schneider   2021-02-03   987  	struct sched_domain *parent;
02d81c8f49452e Valentin Schneider   2021-02-03   988  
02d81c8f49452e Valentin Schneider   2021-02-03   989  	BUG_ON(!(sd->flags & SD_NUMA));
02d81c8f49452e Valentin Schneider   2021-02-03   990  
02d81c8f49452e Valentin Schneider   2021-02-03   991  	/* Get to the level above NODE */
02d81c8f49452e Valentin Schneider   2021-02-03   992  	while (sd && sd->child) {

Presumably this is always true when the function is called so this
warning is a false positive?

02d81c8f49452e Valentin Schneider   2021-02-03   993  		parent = sd;
02d81c8f49452e Valentin Schneider   2021-02-03   994  		sd = sd->child;
02d81c8f49452e Valentin Schneider   2021-02-03   995  
02d81c8f49452e Valentin Schneider   2021-02-03   996  		if (!(sd->flags & SD_NUMA))
02d81c8f49452e Valentin Schneider   2021-02-03   997  			break;
02d81c8f49452e Valentin Schneider   2021-02-03   998  	}
02d81c8f49452e Valentin Schneider   2021-02-03   999  	/*
02d81c8f49452e Valentin Schneider   2021-02-03  1000  	 * We're going to create cross topology level sched_group_capacity
02d81c8f49452e Valentin Schneider   2021-02-03  1001  	 * references. This can only work if the domains resulting from said
02d81c8f49452e Valentin Schneider   2021-02-03  1002  	 * levels won't be degenerated, as we need said sgc to be periodically
02d81c8f49452e Valentin Schneider   2021-02-03  1003  	 * updated: it needs to be attached to the local group of a domain
02d81c8f49452e Valentin Schneider   2021-02-03  1004  	 * that didn't get degenerated.
02d81c8f49452e Valentin Schneider   2021-02-03  1005  	 *
02d81c8f49452e Valentin Schneider   2021-02-03  1006  	 * Of course, groups aren't available yet, so we can't call the usual
02d81c8f49452e Valentin Schneider   2021-02-03  1007  	 * sd_degenerate(). Checking domain spans is the closest we get.
02d81c8f49452e Valentin Schneider   2021-02-03  1008  	 * Start from NODE's parent, and keep going up until we get a domain
02d81c8f49452e Valentin Schneider   2021-02-03  1009  	 * we're sure won't be degenerated.
02d81c8f49452e Valentin Schneider   2021-02-03  1010  	 */
02d81c8f49452e Valentin Schneider   2021-02-03  1011  	while (sd->parent &&
02d81c8f49452e Valentin Schneider   2021-02-03 @1012  	       cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) {
02d81c8f49452e Valentin Schneider   2021-02-03  1013  		sd = parent;
02d81c8f49452e Valentin Schneider   2021-02-03  1014  		parent = sd->parent;
02d81c8f49452e Valentin Schneider   2021-02-03  1015  	}
02d81c8f49452e Valentin Schneider   2021-02-03  1016  
02d81c8f49452e Valentin Schneider   2021-02-03  1017  	return parent;
02d81c8f49452e Valentin Schneider   2021-02-03  1018  }

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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next prev parent reply	other threads:[~2021-02-03 18:38 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-03 15:54 [RFC PATCH 0/2] sched/topology: Get rid of overlapping groups Valentin Schneider
2021-02-03 15:54 ` [RFC PATCH 1/2] sched/topology: Get rid of NUMA " Valentin Schneider
2021-02-03 18:38   ` Dan Carpenter [this message]
2021-02-03 18:38     ` Dan Carpenter
2021-02-03 19:26     ` Valentin Schneider
2021-02-08 10:04   ` Song Bao Hua (Barry Song)
2021-02-08 11:47     ` Valentin Schneider
2021-02-09  0:12       ` Song Bao Hua (Barry Song)
2021-02-09 10:41         ` Valentin Schneider
2021-02-03 15:54 ` [RFC PATCH 2/2] Revert "sched/topology: Warn when NUMA diameter > 2" Valentin Schneider
2021-02-08 10:27   ` Song Bao Hua (Barry Song)
2021-02-03 15:54 ` [RFC PATCH 3/2] sched/topology: Alternative diameter >= 2 fixup Valentin Schneider
  -- strict thread matches above, loose matches on Subject: below --
2021-02-03 18:31 [RFC PATCH 1/2] sched/topology: Get rid of NUMA overlapping groups kernel test robot

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