# \[PATCH v4 03/15\] tracing/filters: Handle out-of-range CPU for OP\_NE in cpumask comparison - From: Masami Hiramatsu (Google) \ - Date: 2026-10-29 01:37:57 - List: linux-trace-kernel - Page: https://ratatoskr.run/linux-trace-kernel/2026/10/17824023 - Thread: https://ratatoskr.run/linux-trace-kernel/2026/10/17824014/t.md ```text From: Masami Hiramatsu (Google) In filter_pred_##size##_cpumask(), if the event's scalar CPU value is out of range (cpu >= nr_cpu_ids), it unconditionally returns 0. However, if the predicate operation is OP_NE (e.g., field != CPUS{0,1}), an out-of-range CPU cannot match any valid CPU in the user-provided cpumask and the condition is satisfied. Returning 0 produces a false negative. Return "pred->op == OP_NE" instead of 0 when cpu >= nr_cpu_ids. Fixes: 3cbec9d7b93d ("tracing/filters: Enable filtering a scalar field by a cpumask") Cc: Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_events_filter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index b35ecb01697b..3f0c73819365 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -759,7 +759,7 @@ static int filter_pred_##size##_cpumask(struct filter_pred *pred, void *event) \ unsigned int cpu = *addr; \ \ if (cpu >= nr_cpu_ids) \ - return 0; \ + return pred->op == OP_NE; \ \ return do_filter_scalar_cpumask(pred->op, cpu, pred->mask); \ } ```