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Date:   Thu, 19 May 2022 10:07:46 +0100
From:   Mel Gorman <mgorman@suse.de>
To:     kernel test robot <lkp@intel.com>
Cc:     kbuild-all@lists.01.org, linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [peterz-queue:sched/core 6/8] kernel/sched/fair.c:9199:30:
 error: implicit declaration of function 'adjust_numa_imbalance'
Message-ID: <20220519090746.GT20579@suse.de>
References: <202205190911.n5iX1ftB-lkp@intel.com>
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On Thu, May 19, 2022 at 09:55:17AM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core
> head:   45ff65aa1bfd4826331c9c4daafdca21ef8f79f8
> commit: c81394419b54c2df2644a34892a6d6434fd922b3 [6/8] sched/numa: Apply imbalance limitations consistently
> config: arc-allyesconfig (https://download.01.org/0day-ci/archive/20220519/202205190911.n5iX1ftB-lkp@intel.com/config)
> compiler: arceb-elf-gcc (GCC) 11.3.0
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?id=c81394419b54c2df2644a34892a6d6434fd922b3
>         git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git
>         git fetch --no-tags peterz-queue sched/core
>         git checkout c81394419b54c2df2644a34892a6d6434fd922b3
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 

Oops, the converged function just needs to move outside of
CONFIG_NUMA_BALANCING as it's not related to automatic NUMA balancing.

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f619d9f70c8da..9b26afefc769b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1043,6 +1043,31 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
  * Scheduling class queueing methods:
  */
 
+#define NUMA_IMBALANCE_MIN 2
+
+static inline long
+adjust_numa_imbalance(int imbalance, int dst_running, int imb_numa_nr)
+{
+	/*
+	 * Allow a NUMA imbalance if busy CPUs is less than the maximum
+	 * threshold. Above this threshold, individual tasks may be contending
+	 * for both memory bandwidth and any shared HT resources.  This is an
+	 * approximation as the number of running tasks may not be related to
+	 * the number of busy CPUs due to sched_setaffinity.
+	 */
+	if (dst_running > imb_numa_nr)
+		return imbalance;
+
+	/*
+	 * Allow a small imbalance based on a simple pair of communicating
+	 * tasks that remain local when the destination is lightly loaded.
+	 */
+	if (imbalance <= NUMA_IMBALANCE_MIN)
+		return 0;
+
+	return imbalance;
+}
+
 #ifdef CONFIG_NUMA_BALANCING
 /*
  * Approximate time to scan a full NUMA task in ms. The task scan period is
@@ -1537,31 +1562,6 @@ struct task_numa_env {
 static unsigned long cpu_load(struct rq *rq);
 static unsigned long cpu_runnable(struct rq *rq);
 
-#define NUMA_IMBALANCE_MIN 2
-
-static inline long
-adjust_numa_imbalance(int imbalance, int dst_running, int imb_numa_nr)
-{
-	/*
-	 * Allow a NUMA imbalance if busy CPUs is less than the maximum
-	 * threshold. Above this threshold, individual tasks may be contending
-	 * for both memory bandwidth and any shared HT resources.  This is an
-	 * approximation as the number of running tasks may not be related to
-	 * the number of busy CPUs due to sched_setaffinity.
-	 */
-	if (dst_running > imb_numa_nr)
-		return imbalance;
-
-	/*
-	 * Allow a small imbalance based on a simple pair of communicating
-	 * tasks that remain local when the destination is lightly loaded.
-	 */
-	if (imbalance <= NUMA_IMBALANCE_MIN)
-		return 0;
-
-	return imbalance;
-}
-
 static inline enum
 numa_type numa_classify(unsigned int imbalance_pct,
 			 struct numa_stats *ns)