2 files changed, 34 insertions, 16 deletions

diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 5932a824547a..e008d236cc15 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -35,7 +35,7 @@
  * Leave an at least ~128 MB hole.
  */
 #define MIN_GAP (128*1024*1024)
-#define MAX_GAP (TASK_SIZE/6*5)
+#define MAX_GAP (STACK_TOP/6*5)
 
 static inline unsigned long mmap_base(void)
 {
@@ -46,7 +46,7 @@ static inline unsigned long mmap_base(void)
         else if (gap > MAX_GAP)
                 gap = MAX_GAP;
 
-        return TASK_SIZE - (gap & PAGE_MASK);
+        return STACK_TOP - (gap & PAGE_MASK);
 }
 
 static inline int mmap_is_legacy(void)
@@ -89,42 +89,58 @@ EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
 
 #else
 
+int s390_mmap_check(unsigned long addr, unsigned long len)
+{
+        if (!test_thread_flag(TIF_31BIT) &&
+            len >= TASK_SIZE && TASK_SIZE < (1UL << 53))
+                return crst_table_upgrade(current->mm, 1UL << 53);
+        return 0;
+}
+
 static unsigned long
 s390_get_unmapped_area(struct file *filp, unsigned long addr,
                 unsigned long len, unsigned long pgoff, unsigned long flags)
 {
         struct mm_struct *mm = current->mm;
+        unsigned long area;
         int rc;
 
-        addr = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
-        if (addr & ~PAGE_MASK)
-                return addr;
-        if (unlikely(mm->context.asce_limit < addr + len)) {
-                rc = crst_table_upgrade(mm, addr + len);
+        area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
+        if (!(area & ~PAGE_MASK))
+                return area;
+        if (area == -ENOMEM &&
+            !test_thread_flag(TIF_31BIT) && TASK_SIZE < (1UL << 53)) {
+                /* Upgrade the page table to 4 levels and retry. */
+                rc = crst_table_upgrade(mm, 1UL << 53);
                 if (rc)
                         return (unsigned long) rc;
+                area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
         }
-        return addr;
+        return area;
 }
 
 static unsigned long
-s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
                           const unsigned long len, const unsigned long pgoff,
                           const unsigned long flags)
 {
         struct mm_struct *mm = current->mm;
-        unsigned long addr = addr0;
+        unsigned long area;
         int rc;
 
-        addr = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
-        if (addr & ~PAGE_MASK)
-                return addr;
-        if (unlikely(mm->context.asce_limit < addr + len)) {
-                rc = crst_table_upgrade(mm, addr + len);
+        area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
+        if (!(area & ~PAGE_MASK))
+                return area;
+        if (area == -ENOMEM &&
+            !test_thread_flag(TIF_31BIT) && TASK_SIZE < (1UL << 53)) {
+                /* Upgrade the page table to 4 levels and retry. */
+                rc = crst_table_upgrade(mm, 1UL << 53);
                 if (rc)
                         return (unsigned long) rc;
+                area = arch_get_unmapped_area_topdown(filp, addr, len,
+                                                      pgoff, flags);
         }
-        return addr;
+        return area;
 }
 /*
  * This function, called very early during the creation of a new
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 0767827540b1..6b6ddc4ea02b 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -117,6 +117,7 @@ repeat:
                 crst_table_init(table, entry);
                 pgd_populate(mm, (pgd_t *) table, (pud_t *) pgd);
                 mm->pgd = (pgd_t *) table;
+                mm->task_size = mm->context.asce_limit;
                 table = NULL;
         }
         spin_unlock(&mm->page_table_lock);
@@ -154,6 +155,7 @@ void crst_table_downgrade(struct mm_struct *mm, unsigned long limit)
                         BUG();
                 }
                 mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
+                mm->task_size = mm->context.asce_limit;
                 crst_table_free(mm, (unsigned long *) pgd);
         }
         update_mm(mm, current);