[S390] make page table upgrade work again

After TASK_SIZE now gives the current size of the address space the
upgrade of a 64 bit process from 3 to 4 levels of page table  needs
to use the arch_mmap_check hook to catch large mmap lengths. The
get_unmapped_area* functions need to check for -ENOMEM from the
arch_get_unmapped_area*, upgrade the page table and retry.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 35 insertions, 14 deletions

diff --git a/arch/s390/include/asm/mman.h b/arch/s390/include/asm/mman.h
index 7839767d837..da01432e8f4 100644
--- a/arch/s390/include/asm/mman.h
+++ b/arch/s390/include/asm/mman.h
@@ -22,4 +22,9 @@
 #define MCL_CURRENT     1               /* lock all current mappings */
 #define MCL_FUTURE      2               /* lock all future mappings */
 
+#if defined(__KERNEL__) && !defined(__ASSEMBLY__) && defined(CONFIG_64BIT)
+int s390_mmap_check(unsigned long addr, unsigned long len);
+#define arch_mmap_check(addr,len,flags) s390_mmap_check(addr,len)
+#endif
+
 #endif /* __S390_MMAN_H__ */
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 346dd0c5cbd..e008d236cc1 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -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