[RFC/PATCH] mm/futex: Fix futex writes on archs with SW tracking of dirty & young

[Peter Zijlstra]

On Wed, 2011-07-27 at 17:58 +1000, Benjamin Herrenschmidt wrote:

> What should nommu do anyways ? it's not like there's much it can do
> right ? It should never even hit the fault path to start with ...

Something like the below makes a nommu arm config build.. David, is this
indeed the correct thing to do for nommu?

---
Index: linux-2.6/mm/nommu.c
===================================================================
--- linux-2.6.orig/mm/nommu.c
+++ linux-2.6/mm/nommu.c
@@ -190,6 +190,12 @@ int get_user_pages(struct task_struct *t
 }
 EXPORT_SYMBOL(get_user_pages);
 
+int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
+		     unsigned long address, unsigned int fault_flags)
+{
+	BUG(); /* nommu should never call this */
+}
+
 /**
  * follow_pfn - look up PFN at a user virtual address
  * @vma: memory mapping