On Tue, Sep 14, 2021 at 5:11 AM Ard Biesheuvel [off-list ref] wrote:

 static inline unsigned int task_cpu(const struct task_struct *p)
 {
 #ifdef CONFIG_THREAD_INFO_IN_TASK
-       return READ_ONCE(p->cpu);
+       return READ_ONCE(p->thread_info.cpu);
 #else
        return READ_ONCE(task_thread_info(p)->cpu);
 #endif

Those two lines look different, but aren't.

Please just remove the CONFIG_THREAD_INFO_IN_TASK conditional, and use

          return READ_ONCE(task_thread_info(p)->cpu);

unconditionally, which now does the right thing regardless.

             Linus