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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Nov 2025 02:57:15.4997 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ec67ba08-b1aa-4473-0859-08de1da95b8a X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SA2PEPF00003AE9.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR12MB4056 Hello Tim, On 11/7/2025 4:57 AM, Tim Chen wrote: > @@ -11757,6 +11772,7 @@ static int sched_balance_rq(int this_cpu, struct rq *this_rq, > .fbq_type = all, > .tasks = LIST_HEAD_INIT(env.tasks), > }; > + int need_unlock = false; > > cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask); > > @@ -11768,6 +11784,13 @@ static int sched_balance_rq(int this_cpu, struct rq *this_rq, > goto out_balanced; > } > > + if (idle != CPU_NEWLY_IDLE && (sd->flags & SD_SERIALIZE)) { > + if (atomic_cmpxchg_acquire(&sched_balance_running, 0, 1)) { > + goto out_balanced; > + } > + need_unlock = true; > + } > + > group = sched_balance_find_src_group(&env); > if (!group) { > schedstat_inc(sd->lb_nobusyg[idle]); > @@ -11892,6 +11915,9 @@ static int sched_balance_rq(int this_cpu, struct rq *this_rq, > if (!cpumask_subset(cpus, env.dst_grpmask)) { > env.loop = 0; > env.loop_break = SCHED_NR_MIGRATE_BREAK; > + if (need_unlock) > + atomic_set_release(&sched_balance_running, 0); I believe we should reset "need_unlock" to false here since "redo" can fail the atomic_cmpxchg_acquire() while still having "need_unlock" set to "true" and the "out_balanced" path will then perform the atomic_set_release() when another CPU is in middle of a busy / idle balance on a SD_SERIALIZE domain. We can also initialize the "need_unlock" to false just after the redo label too - whichever you prefer. nit. "need_unlock" can just be a bool instead of an int. Apart from that, feel free to include: Reviewed-by: K Prateek Nayak > + > goto redo; > } > goto out_all_pinned; > @@ -12008,6 +12034,9 @@ static int sched_balance_rq(int this_cpu, struct rq *this_rq, > sd->balance_interval < sd->max_interval) > sd->balance_interval *= 2; > out: > + if (need_unlock) > + atomic_set_release(&sched_balance_running, 0); > + > return ld_moved; > } > -- Thanks and Regards, Prateek