6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxx>
Reported-by: kernelci.org bot <bot@xxxxxxxxxxxx>
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
