6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Linus Torvalds torvalds@linux-foundation.org
commit cec6937dd1aae1b38d147bd190cb895d06cf96d0 upstream.
The TWA_NMI_CURRENT handling very much depends on IRQ_WORK, but that isn't universally enabled everywhere.
Maybe the IRQ_WORK infrastructure should just be unconditional - x86 ends up indirectly enabling it through unconditionally enabling PERF_EVENTS, for example. But it also gets enabled by having SMP support, or even if you just have PRINTK enabled.
But in the meantime TWA_NMI_CURRENT causes tons of build failures on various odd minimal configs. Which did show up in linux-next, but despite that nobody bothered to fix it or even inform me until -rc1 was out.
Fixes: 466e4d801cd4 ("task_work: Add TWA_NMI_CURRENT as an additional notify mode") Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Reported-by: kernelci.org bot bot@kernelci.org Reported-by: Guenter Roeck linux@roeck-us.net Cc: Peter Zijlstra peterz@infradead.org Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/task_work.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -6,12 +6,14 @@
static struct callback_head work_exited; /* all we need is ->next == NULL */
+#ifdef CONFIG_IRQ_WORK static void task_work_set_notify_irq(struct irq_work *entry) { test_and_set_tsk_thread_flag(current, TIF_NOTIFY_RESUME); } static DEFINE_PER_CPU(struct irq_work, irq_work_NMI_resume) = IRQ_WORK_INIT_HARD(task_work_set_notify_irq); +#endif
/** * task_work_add - ask the @task to execute @work->func() @@ -59,6 +61,8 @@ int task_work_add(struct task_struct *ta if (notify == TWA_NMI_CURRENT) { if (WARN_ON_ONCE(task != current)) return -EINVAL; + if (!IS_ENABLED(CONFIG_IRQ_WORK)) + return -EINVAL; } else { /* * Record the work call stack in order to print it in KASAN @@ -92,9 +96,11 @@ int task_work_add(struct task_struct *ta case TWA_SIGNAL_NO_IPI: __set_notify_signal(task); break; +#ifdef CONFIG_IRQ_WORK case TWA_NMI_CURRENT: irq_work_queue(this_cpu_ptr(&irq_work_NMI_resume)); break; +#endif default: WARN_ON_ONCE(1); break;