Re: [RFC PATCH v5 8/9] sched/fair: Steal work from an overloaded CPU when CPU goes idle

[kernel test robot <lkp@intel.com>]

Hi Chen,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v7.0-rc5]
[cannot apply to tip/sched/core peterz-queue/sched/core next-20260320]
[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/Chen-Jinghuang/sched-Provide-sparsemask-a-reduced-contention-bitmap/20260321-084706
base:   linus/master
patch link:    https://lore.kernel.org/r/20260320055920.2518389-9-chenjinghuang2%40huawei.com
patch subject: [RFC PATCH v5 8/9] sched/fair: Steal work from an overloaded CPU when CPU goes idle
config: riscv-allmodconfig (https://download.01.org/0day-ci/archive/20260323/202603231203.g4WzI66q-lkp@intel.com/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project b1cf9b0835d214bcbd0d6e8882760c07cfccb298)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260323/202603231203.g4WzI66q-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603231203.g4WzI66q-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/sched/fair.c:13272:3: warning: releasing raw_spinlock 'rq_lockp(dst_rq)' that was not held [-Wthread-safety-analysis]
    13272 |                 raw_spin_rq_unlock(dst_rq);
          |                 ^
   kernel/sched/fair.c:13293:2: warning: raw_spinlock 'rq_lockp(dst_rq)' is not held on every path through here [-Wthread-safety-analysis]
    13293 |         local_irq_restore(rf.flags);
          |         ^
   include/linux/irqflags.h:223:8: note: expanded from macro 'local_irq_restore'
     223 |                 if (!raw_irqs_disabled_flags(flags))    \
         |                      ^
   include/linux/irqflags.h:188:13: note: expanded from macro 'raw_irqs_disabled_flags'
     188 |                 typecheck(unsigned long, flags);        \
         |                           ^
   kernel/sched/fair.c:13286:3: note: raw_spinlock acquired here
    13286 |                 raw_spin_rq_lock(dst_rq);
          |                 ^
>> kernel/sched/fair.c:13366:2: warning: raw_spinlock 'rq_lockp(this_rq)' is not held on every path through here [-Wthread-safety-analysis]
    13366 |         stolen |= (dst_rq->cfs.h_nr_runnable > 0);
          |         ^
   kernel/sched/fair.c:13363:3: note: raw_spinlock acquired here
    13363 |                 raw_spin_rq_lock(dst_rq);
          |                 ^
   3 warnings generated.


vim +13366 kernel/sched/fair.c

 13350	
 13351		/* Accept any suitable task in the LLC */
 13352	
 13353		sparsemask_for_each(overload_cpus, dst_cpu, src_cpu) {
 13354			if (steal_from(dst_rq, dst_rf, &locked, src_cpu)) {
 13355				stolen = 1;
 13356				goto out;
 13357			}
 13358		}
 13359	
 13360	out:
 13361		rcu_read_unlock();
 13362		if (!locked) {
 13363			raw_spin_rq_lock(dst_rq);
 13364			rq_repin_lock(dst_rq, dst_rf);
 13365		}
 13366		stolen |= (dst_rq->cfs.h_nr_runnable > 0);
 13367		if (dst_rq->nr_running != dst_rq->cfs.h_nr_runnable)
 13368			stolen = -1;
 13369		return stolen;
 13370	}
 13371	

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