NUMA-Q breakage 5/7 in_interrupt() race

On smaller machines, bootstrapping proceeds far enough to see races in kmaps near generic_file_read() etc. This is precisely the in_interrupt() BUG(), but it's quite clear this is happening in process context. Not even the smaller machines can survive this. That is, it is impossible to run at all without it (or an equivalent).

Robert, please apply.

Thanks,
Bill

===== include/asm-i386/hardirq.h 1.7 vs edited =====

@@ -22,8 +22,24 @@
  * Are we in an interrupt context? Either doing bottom half
  * or hardware interrupt processing?
  */
-#define in_interrupt() ({ int __cpu = smp_processor_id(); \
-	(local_irq_count(__cpu) + local_bh_count(__cpu) != 0); })
+static inline int in_interrupt(void)
+{
+	int total_count, retval, cpu;
+
+	preempt_disable();
+	cpu = smp_processor_id();
+
+	total_count = local_irq_count(cpu) + local_bh_count(cpu);
+
+	if (total_count)
+		retval = 1;
+	else
+		retval = 0;
+
+	preempt_disable();
+
+	return retval;
+}
 
 #define in_irq() (local_irq_count(smp_processor_id()) != 0)
 

Argh, I forgot to credit Rusty Russell (and possibly also Paul Mackerras) with originally discovering & fixing this.

Cheers,
Bill

Hi,

While we're on it, thanks from me, too.

Regards, Thunder

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