[peterz-queue:master 6/13] kernel/sched/psi.c:973:6: sparse: sparse: context imbalance in 'cgroup_move_task' - different lock contexts for basic block

[peterz-queue:master 6/13] kernel/sched/psi.c:973:6: sparse: sparse: context imbalance in 'cgroup_move_task' - different lock contexts for basic block

[kernel test robot]

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CC: kbuild-all(a)lists.01.org
TO: Peter Zijlstra <peterz@infradead.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git master
head:   855f695048dbed44a7d9574a7e3d65c4637ea39d
commit: 0cee7807ddccacebbca1a9b40894e904682066e9 [6/13] Merge branch 'sched/core-sched'
:::::: branch date: 4 hours ago
:::::: commit date: 4 hours ago
config: x86_64-randconfig-s021-20210504 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-341-g8af24329-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?id=0cee7807ddccacebbca1a9b40894e904682066e9
        git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git
        git fetch --no-tags peterz-queue master
        git checkout 0cee7807ddccacebbca1a9b40894e904682066e9
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=x86_64 

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


sparse warnings: (new ones prefixed by >>)
   kernel/sched/psi.c:1249:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
   kernel/sched/psi.c:1249:9: sparse:    void [noderef] __rcu *
   kernel/sched/psi.c:1249:9: sparse:    void *
   kernel/sched/psi.c:731:13: sparse: sparse: dereference of noderef expression
   kernel/sched/psi.c:751:30: sparse: sparse: dereference of noderef expression
>> kernel/sched/psi.c:973:6: sparse: sparse: context imbalance in 'cgroup_move_task' - different lock contexts for basic block

vim +/cgroup_move_task +973 kernel/sched/psi.c

2ce7135adc9ad0 Johannes Weiner 2018-10-26   960  
2ce7135adc9ad0 Johannes Weiner 2018-10-26   961  /**
2ce7135adc9ad0 Johannes Weiner 2018-10-26   962   * cgroup_move_task - move task to a different cgroup
2ce7135adc9ad0 Johannes Weiner 2018-10-26   963   * @task: the task
2ce7135adc9ad0 Johannes Weiner 2018-10-26   964   * @to: the target css_set
2ce7135adc9ad0 Johannes Weiner 2018-10-26   965   *
2ce7135adc9ad0 Johannes Weiner 2018-10-26   966   * Move task to a new cgroup and safely migrate its associated stall
2ce7135adc9ad0 Johannes Weiner 2018-10-26   967   * state between the different groups.
2ce7135adc9ad0 Johannes Weiner 2018-10-26   968   *
2ce7135adc9ad0 Johannes Weiner 2018-10-26   969   * This function acquires the task's rq lock to lock out concurrent
2ce7135adc9ad0 Johannes Weiner 2018-10-26   970   * changes to the task's scheduling state and - in case the task is
2ce7135adc9ad0 Johannes Weiner 2018-10-26   971   * running - concurrent changes to its stall state.
2ce7135adc9ad0 Johannes Weiner 2018-10-26   972   */
2ce7135adc9ad0 Johannes Weiner 2018-10-26  @973  void cgroup_move_task(struct task_struct *task, struct css_set *to)
2ce7135adc9ad0 Johannes Weiner 2018-10-26   974  {
ea3e5f897bbc91 Johannes Weiner 2021-05-03   975  	unsigned int task_flags;
2ce7135adc9ad0 Johannes Weiner 2018-10-26   976  	struct rq_flags rf;
2ce7135adc9ad0 Johannes Weiner 2018-10-26   977  	struct rq *rq;
2ce7135adc9ad0 Johannes Weiner 2018-10-26   978  
e0c274472d5d27 Johannes Weiner 2018-11-30   979  	if (static_branch_likely(&psi_disabled)) {
8fcb2312d1e330 Olof Johansson  2018-11-16   980  		/*
8fcb2312d1e330 Olof Johansson  2018-11-16   981  		 * Lame to do this here, but the scheduler cannot be locked
8fcb2312d1e330 Olof Johansson  2018-11-16   982  		 * from the outside, so we move cgroups from inside sched/.
8fcb2312d1e330 Olof Johansson  2018-11-16   983  		 */
8fcb2312d1e330 Olof Johansson  2018-11-16   984  		rcu_assign_pointer(task->cgroups, to);
8fcb2312d1e330 Olof Johansson  2018-11-16   985  		return;
8fcb2312d1e330 Olof Johansson  2018-11-16   986  	}
8fcb2312d1e330 Olof Johansson  2018-11-16   987  
2ce7135adc9ad0 Johannes Weiner 2018-10-26   988  	rq = task_rq_lock(task, &rf);
2ce7135adc9ad0 Johannes Weiner 2018-10-26   989  
ea3e5f897bbc91 Johannes Weiner 2021-05-03   990  	/*
ea3e5f897bbc91 Johannes Weiner 2021-05-03   991  	 * We may race with schedule() dropping the rq lock between
ea3e5f897bbc91 Johannes Weiner 2021-05-03   992  	 * deactivating prev and switching to next. Because the psi
ea3e5f897bbc91 Johannes Weiner 2021-05-03   993  	 * updates from the deactivation are deferred to the switch
ea3e5f897bbc91 Johannes Weiner 2021-05-03   994  	 * callback to save cgroup tree updates, the task's scheduling
ea3e5f897bbc91 Johannes Weiner 2021-05-03   995  	 * state here is not coherent with its psi state:
ea3e5f897bbc91 Johannes Weiner 2021-05-03   996  	 *
ea3e5f897bbc91 Johannes Weiner 2021-05-03   997  	 * schedule()                   cgroup_move_task()
ea3e5f897bbc91 Johannes Weiner 2021-05-03   998  	 *   rq_lock()
ea3e5f897bbc91 Johannes Weiner 2021-05-03   999  	 *   deactivate_task()
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1000  	 *     p->on_rq = 0
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1001  	 *     psi_dequeue() // defers TSK_RUNNING & TSK_IOWAIT updates
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1002  	 *   pick_next_task()
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1003  	 *     rq_unlock()
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1004  	 *                                rq_lock()
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1005  	 *                                psi_task_change() // old cgroup
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1006  	 *                                task->cgroups = to
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1007  	 *                                psi_task_change() // new cgroup
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1008  	 *                                rq_unlock()
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1009  	 *     rq_lock()
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1010  	 *   psi_sched_switch() // does deferred updates in new cgroup
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1011  	 *
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1012  	 * Don't rely on the scheduling state. Use psi_flags instead.
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1013  	 */
ea3e5f897bbc91 Johannes Weiner 2021-05-03  1014  	task_flags = task->psi_flags;
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1015  
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1016  	if (task_flags)
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1017  		psi_task_change(task, task_flags, 0);
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1018  
8fcb2312d1e330 Olof Johansson  2018-11-16  1019  	/* See comment above */
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1020  	rcu_assign_pointer(task->cgroups, to);
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1021  
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1022  	if (task_flags)
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1023  		psi_task_change(task, 0, task_flags);
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1024  
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1025  	task_rq_unlock(rq, task, &rf);
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1026  }
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1027  #endif /* CONFIG_CGROUPS */
2ce7135adc9ad0 Johannes Weiner 2018-10-26  1028  

:::::: The code at line 973 was first introduced by commit
:::::: 2ce7135adc9ad081aa3c49744144376ac74fea60 psi: cgroup support

:::::: TO: Johannes Weiner <hannes@cmpxchg.org>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>

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

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