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Date:   Thu, 1 Jun 2023 22:33:54 +0800
From:   kernel test robot <lkp@intel.com>
To:     John Stultz <jstultz@google.com>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev,
        Connor O'Brien <connoro@google.com>,
        Joel Fernandes <joelaf@google.com>,
        Qais Yousef <qyousef@google.com>,
        Ingo Molnar <mingo@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Valentin Schneider <vschneid@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>,
        Zimuzo Ezeozue <zezeozue@google.com>,
        Youssef Esmat <youssefesmat@google.com>,
        Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Will Deacon <will@kernel.org>,
        Waiman Long <longman@redhat.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        "Paul E . McKenney" <paulmck@kernel.org>, kernel-team@android.com,
        John Stultz <jstultz@google.com>
Subject: Re: [PATCH v4 12/13] sched: Attempt to fix rt/dl load balancing via
 chain level balance
Message-ID: <202306012038.LYIa7RLC-lkp@intel.com>
References: <20230601055846.2349566-13-jstultz@google.com>
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In-Reply-To: <20230601055846.2349566-13-jstultz@google.com>
Precedence: bulk

Hi John,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/sched/core]
[also build test WARNING on tip/locking/core tip/master tip/auto-latest linus/master v6.4-rc4 next-20230601]
[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/John-Stultz/sched-Unify-runtime-accounting-across-classes/20230601-140200
base:   tip/sched/core
patch link:    https://lore.kernel.org/r/20230601055846.2349566-13-jstultz%40google.com
patch subject: [PATCH v4 12/13] sched: Attempt to fix rt/dl load balancing via chain level balance
config: hexagon-randconfig-r013-20230531 (https://download.01.org/0day-ci/archive/20230601/202306012038.LYIa7RLC-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project 4faf3aaf28226a4e950c103a14f6fc1d1fdabb1b)
reproduce (this is a W=1 build):
        mkdir -p ~/bin
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/82593266398c6feaed3ed5ec458986d8e16b6b74
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review John-Stultz/sched-Unify-runtime-accounting-across-classes/20230601-140200
        git checkout 82593266398c6feaed3ed5ec458986d8e16b6b74
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=hexagon olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash kernel/sched/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306012038.LYIa7RLC-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from kernel/sched/core.c:9:
   In file included from include/linux/highmem.h:12:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __raw_readb(PCI_IOBASE + addr);
                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
   #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
                                                     ^
   In file included from kernel/sched/core.c:9:
   In file included from include/linux/highmem.h:12:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
                                                     ^
   In file included from kernel/sched/core.c:9:
   In file included from include/linux/highmem.h:12:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writeb(value, PCI_IOBASE + addr);
                               ~~~~~~~~~~ ^
   include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   kernel/sched/core.c:3858:30: error: no member named 'cpu' in 'struct rq'
                   set_task_cpu(task, dst_rq->cpu);
                                      ~~~~~~  ^
>> kernel/sched/core.c:3838:6: warning: no previous prototype for function 'push_task_chain' [-Wmissing-prototypes]
   void push_task_chain(struct rq *rq, struct rq *dst_rq, struct task_struct *task)
        ^
   kernel/sched/core.c:3838:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void push_task_chain(struct rq *rq, struct rq *dst_rq, struct task_struct *task)
   ^
   static 
>> kernel/sched/core.c:3870:21: warning: no previous prototype for function 'find_exec_ctx' [-Wmissing-prototypes]
   struct task_struct *find_exec_ctx(struct rq *rq, struct task_struct *p)
                       ^
   kernel/sched/core.c:3870:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   struct task_struct *find_exec_ctx(struct rq *rq, struct task_struct *p)
   ^
   static 
>> kernel/sched/core.c:3898:5: warning: no previous prototype for function 'pushable_chain' [-Wmissing-prototypes]
   int pushable_chain(struct rq *rq, struct task_struct *p, int cpu)
       ^
   kernel/sched/core.c:3898:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int pushable_chain(struct rq *rq, struct task_struct *p, int cpu)
   ^
   static 
   9 warnings and 1 error generated.


vim +/push_task_chain +3838 kernel/sched/core.c

  3837	
> 3838	void push_task_chain(struct rq *rq, struct rq *dst_rq, struct task_struct *task)
  3839	{
  3840		struct task_struct *owner;
  3841	
  3842		lockdep_assert_rq_held(rq);
  3843		lockdep_assert_rq_held(dst_rq);
  3844	
  3845		BUG_ON(!task_queued_on_rq(rq, task));
  3846		BUG_ON(task_current_selected(rq, task));
  3847	
  3848		while (task) {
  3849			if (!task_queued_on_rq(rq, task) || task_current_selected(rq, task))
  3850				break;
  3851	
  3852			if (task_is_blocked(task))
  3853				owner = __mutex_owner(task->blocked_on);
  3854			else
  3855				owner = NULL;
  3856	
  3857			deactivate_task(rq, task, 0);
  3858			set_task_cpu(task, dst_rq->cpu);
  3859			activate_task(dst_rq, task, 0);
  3860			if (task == owner)
  3861				break;
  3862			task = owner;
  3863		}
  3864	}
  3865	
  3866	/*
  3867	 * Returns the unblocked task at the end of the blocked chain starting with p
  3868	 * if that chain is composed entirely of tasks enqueued on rq, or NULL otherwise.
  3869	 */
> 3870	struct task_struct *find_exec_ctx(struct rq *rq, struct task_struct *p)
  3871	{
  3872		struct task_struct *exec_ctx, *owner;
  3873		struct mutex *mutex;
  3874	
  3875		lockdep_assert_rq_held(rq);
  3876	
  3877		for (exec_ctx = p; task_is_blocked(exec_ctx) && !task_on_cpu(rq, exec_ctx);
  3878								exec_ctx = owner) {
  3879			mutex = exec_ctx->blocked_on;
  3880			owner = __mutex_owner(mutex);
  3881			if (owner == exec_ctx)
  3882				break;
  3883	
  3884			if (!task_queued_on_rq(rq, owner) || task_current_selected(rq, owner)) {
  3885				exec_ctx = NULL;
  3886				break;
  3887			}
  3888		}
  3889		return exec_ctx;
  3890	}
  3891	
  3892	/*
  3893	 * Returns:
  3894	 * 1 if chain is pushable and affinity does not prevent pushing to cpu
  3895	 * 0 if chain is unpushable
  3896	 * -1 if chain is pushable but affinity blocks running on cpu.
  3897	 */
> 3898	int pushable_chain(struct rq *rq, struct task_struct *p, int cpu)
  3899	{
  3900		struct task_struct *exec_ctx;
  3901	
  3902		lockdep_assert_rq_held(rq);
  3903	
  3904		if (task_rq(p) != rq || !task_on_rq_queued(p))
  3905			return 0;
  3906	
  3907		exec_ctx = find_exec_ctx(rq, p);
  3908		/*
  3909		 * Chain leads off the rq, we're free to push it anywhere.
  3910		 *
  3911		 * One wrinkle with relying on find_exec_ctx is that when the chain
  3912		 * leads to a task currently migrating to rq, we see the chain as
  3913		 * pushable & push everything prior to the migrating task. Even if
  3914		 * we checked explicitly for this case, we could still race with a
  3915		 * migration after the check.
  3916		 * This shouldn't permanently produce a bad state though, as proxy()
  3917		 * will send the chain back to rq and by that point the migration
  3918		 * should be complete & a proper push can occur.
  3919		 */
  3920		if (!exec_ctx)
  3921			return 1;
  3922	
  3923		if (task_on_cpu(rq, exec_ctx) || exec_ctx->nr_cpus_allowed <= 1)
  3924			return 0;
  3925	
  3926		return cpumask_test_cpu(cpu, &exec_ctx->cpus_mask) ? 1 : -1;
  3927	}
  3928	

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