From db08b1940f4beb25460b4a4e9da3446454f2e8fe Mon Sep 17 00:00:00 2001 From: Cheng-Yang Chou Date: Sat, 21 Mar 2026 18:54:58 +0800 Subject: sched_ext: Fix inconsistent NUMA node lookup in scx_select_cpu_dfl() In the WAKE_SYNC path of scx_select_cpu_dfl(), waker_node was computed with cpu_to_node(), while node (for prev_cpu) was computed with scx_cpu_node_if_enabled(). When scx_builtin_idle_per_node is disabled, idle_cpumask(waker_node) is called with a real node ID even though per-node idle tracking is disabled, resulting in undefined behavior. Fix by using scx_cpu_node_if_enabled() for waker_node as well, ensuring both variables are computed consistently. Fixes: 48849271e6611 ("sched_ext: idle: Per-node idle cpumasks") Cc: stable@vger.kernel.org # v6.15+ Signed-off-by: Cheng-Yang Chou Reviewed-by: Andrea Righi Signed-off-by: Tejun Heo --- kernel/sched/ext_idle.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c index ba298ac3ce6c..0ae93cd64004 100644 --- a/kernel/sched/ext_idle.c +++ b/kernel/sched/ext_idle.c @@ -543,7 +543,7 @@ s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, * piled up on it even if there is an idle core elsewhere on * the system. */ - waker_node = cpu_to_node(cpu); + waker_node = scx_cpu_node_if_enabled(cpu); if (!(current->flags & PF_EXITING) && cpu_rq(cpu)->scx.local_dsq.nr == 0 && (!(flags & SCX_PICK_IDLE_IN_NODE) || (waker_node == node)) && -- cgit v1.2.3