Re: [PATCH v3 3/5] sched/fair: Switch to task based throttle model

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

Hi Aaron,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/sched/core]
[also build test WARNING on next-20250715]
[cannot apply to linus/master v6.16-rc6]
[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/Aaron-Lu/sched-fair-Add-related-data-structure-for-task-based-throttle/20250715-152307
base:   tip/sched/core
patch link:    https://lore.kernel.org/r/20250715071658.267-4-ziqianlu%40bytedance.com
patch subject: [PATCH v3 3/5] sched/fair: Switch to task based throttle model
config: i386-buildonly-randconfig-006-20250716 (https://download.01.org/0day-ci/archive/20250716/202507160730.0cXkgs0S-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250716/202507160730.0cXkgs0S-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/202507160730.0cXkgs0S-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/sched/fair.c:5456:33: warning: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Wsingle-bit-bitfield-constant-conversion]
    5456 |                         cfs_rq->pelt_clock_throttled = 1;
         |                                                      ^ ~
   kernel/sched/fair.c:5971:32: warning: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Wsingle-bit-bitfield-constant-conversion]
    5971 |                 cfs_rq->pelt_clock_throttled = 1;
         |                                              ^ ~
   kernel/sched/fair.c:6014:20: warning: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Wsingle-bit-bitfield-constant-conversion]
    6014 |         cfs_rq->throttled = 1;
         |                           ^ ~
   3 warnings generated.


vim +/int +5456 kernel/sched/fair.c

  5372	
  5373	static bool
  5374	dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
  5375	{
  5376		bool sleep = flags & DEQUEUE_SLEEP;
  5377		int action = UPDATE_TG;
  5378	
  5379		update_curr(cfs_rq);
  5380		clear_buddies(cfs_rq, se);
  5381	
  5382		if (flags & DEQUEUE_DELAYED) {
  5383			WARN_ON_ONCE(!se->sched_delayed);
  5384		} else {
  5385			bool delay = sleep;
  5386			/*
  5387			 * DELAY_DEQUEUE relies on spurious wakeups, special task
  5388			 * states must not suffer spurious wakeups, excempt them.
  5389			 */
  5390			if (flags & DEQUEUE_SPECIAL)
  5391				delay = false;
  5392	
  5393			WARN_ON_ONCE(delay && se->sched_delayed);
  5394	
  5395			if (sched_feat(DELAY_DEQUEUE) && delay &&
  5396			    !entity_eligible(cfs_rq, se)) {
  5397				update_load_avg(cfs_rq, se, 0);
  5398				set_delayed(se);
  5399				return false;
  5400			}
  5401		}
  5402	
  5403		if (entity_is_task(se) && task_on_rq_migrating(task_of(se)))
  5404			action |= DO_DETACH;
  5405	
  5406		/*
  5407		 * When dequeuing a sched_entity, we must:
  5408		 *   - Update loads to have both entity and cfs_rq synced with now.
  5409		 *   - For group_entity, update its runnable_weight to reflect the new
  5410		 *     h_nr_runnable of its group cfs_rq.
  5411		 *   - Subtract its previous weight from cfs_rq->load.weight.
  5412		 *   - For group entity, update its weight to reflect the new share
  5413		 *     of its group cfs_rq.
  5414		 */
  5415		update_load_avg(cfs_rq, se, action);
  5416		se_update_runnable(se);
  5417	
  5418		update_stats_dequeue_fair(cfs_rq, se, flags);
  5419	
  5420		update_entity_lag(cfs_rq, se);
  5421		if (sched_feat(PLACE_REL_DEADLINE) && !sleep) {
  5422			se->deadline -= se->vruntime;
  5423			se->rel_deadline = 1;
  5424		}
  5425	
  5426		if (se != cfs_rq->curr)
  5427			__dequeue_entity(cfs_rq, se);
  5428		se->on_rq = 0;
  5429		account_entity_dequeue(cfs_rq, se);
  5430	
  5431		/* return excess runtime on last dequeue */
  5432		return_cfs_rq_runtime(cfs_rq);
  5433	
  5434		update_cfs_group(se);
  5435	
  5436		/*
  5437		 * Now advance min_vruntime if @se was the entity holding it back,
  5438		 * except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be
  5439		 * put back on, and if we advance min_vruntime, we'll be placed back
  5440		 * further than we started -- i.e. we'll be penalized.
  5441		 */
  5442		if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE)
  5443			update_min_vruntime(cfs_rq);
  5444	
  5445		if (flags & DEQUEUE_DELAYED)
  5446			finish_delayed_dequeue_entity(se);
  5447	
  5448		if (cfs_rq->nr_queued == 0) {
  5449			update_idle_cfs_rq_clock_pelt(cfs_rq);
  5450	#ifdef CONFIG_CFS_BANDWIDTH
  5451			if (throttled_hierarchy(cfs_rq)) {
  5452				struct rq *rq = rq_of(cfs_rq);
  5453	
  5454				list_del_leaf_cfs_rq(cfs_rq);
  5455				cfs_rq->throttled_clock_pelt = rq_clock_pelt(rq);
> 5456				cfs_rq->pelt_clock_throttled = 1;
  5457			}
  5458	#endif
  5459		}
  5460	
  5461		return true;
  5462	}
  5463	

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