[PATCH] Add NOPFN_REFAULT result from vm_ops->nopfn()

Add a NOPFN_REFAULT return code for vm_ops->nopfn() equivalent to
NOPAGE_REFAULT for vmops->nopage() indicating that the handler requests a
re-execution of the faulting instruction

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 5 insertions, 2 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 903f3b71f4a7..a0eec16eb0bd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -637,6 +637,7 @@ static inline int page_mapped(struct page *page)
  */
 #define NOPFN_SIGBUS    ((unsigned long) -1)
 #define NOPFN_OOM       ((unsigned long) -2)
+#define NOPFN_REFAULT   ((unsigned long) -3)
 
 /*
  * Different kinds of faults, as returned by handle_mm_fault().
diff --git a/mm/memory.c b/mm/memory.c
index 8b8f0d2b453d..e7066e71dfa3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2355,10 +2355,12 @@ static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
         BUG_ON(is_cow_mapping(vma->vm_flags));
 
         pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
-        if (pfn == NOPFN_OOM)
+        if (unlikely(pfn == NOPFN_OOM))
                 return VM_FAULT_OOM;
-        if (pfn == NOPFN_SIGBUS)
+        else if (unlikely(pfn == NOPFN_SIGBUS))
                 return VM_FAULT_SIGBUS;
+        else if (unlikely(pfn == NOPFN_REFAULT))
+                return VM_FAULT_MINOR;
 
         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);