[PATCH] s390: superflous flush_tlb_range calls.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

while searching for a s390 tlb flush problem I noticed some superflous tlb
flushes.  One in zeromap_page_range, one in remap_page_range, and another one
in filemap_sync.  The patch just adds comments but I think these three
flush_tlb_range calls can be removed.

mm/memory.c

@@ -863,6 +863,9 @@ int zeromap_page_range(struct vm_area_struct *vma, unsigned long address, unsign
 		address = (address + PGDIR_SIZE) & PGDIR_MASK;
 		dir++;
 	} while (address && (address < end));
+	/*
+	 * Why flush? zeromap_pte_range has a BUG_ON for !pte_none()
+	 */
 	flush_tlb_range(vma, beg, end);
 	spin_unlock(&mm->page_table_lock);
 	return error;
@@ -944,6 +947,9 @@ int remap_page_range(struct vm_area_struct *vma, unsigned long from, unsigned lo
 		from = (from + PGDIR_SIZE) & PGDIR_MASK;
 		dir++;
 	} while (from && (from < end));
+	/*
+	 * Why flush? remap_pte_range has a BUG_ON for !pte_none()
+	 */
 	flush_tlb_range(vma, beg, end);
 	spin_unlock(&mm->page_table_lock);
 	return error;

mm/msync.c

@@ -113,6 +113,10 @@ static int filemap_sync(struct vm_area_struct * vma, unsigned long address,
 		address = (address + PGDIR_SIZE) & PGDIR_MASK;
 		dir++;
 	} while (address && (address < end));
+	/*
+	 * Why flush ? filemap_sync_pte already flushed the tlbs with the
+	 * dirty bits.
+	 */
 	flush_tlb_range(vma, end - size, end);
 
 	spin_unlock(&vma->vm_mm->page_table_lock);