[S390] gmap: always up mmap_sem properly

If gmap_unmap_segment figures that the segment was not mapped in the
first place, it need to up mmap_sem on exit.

Cc: <stable@kernel.org>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index f69ff3c..5d56c2b 100644 (file)
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -303,15 +303,15 @@ int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len)
                /* Walk the guest addr space page table */
                table = gmap->table + (((to + off) >> 53) & 0x7ff);
                if (*table & _REGION_ENTRY_INV)
-                       return 0;
+                       goto out;
                table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
                table = table + (((to + off) >> 42) & 0x7ff);
                if (*table & _REGION_ENTRY_INV)
-                       return 0;
+                       goto out;
                table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
                table = table + (((to + off) >> 31) & 0x7ff);
                if (*table & _REGION_ENTRY_INV)
-                       return 0;
+                       goto out;
                table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
                table = table + (((to + off) >> 20) & 0x7ff);
 
@@ -319,6 +319,7 @@ int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len)
                flush |= gmap_unlink_segment(gmap, table);
                *table = _SEGMENT_ENTRY_INV;
        }
+out:
        up_read(&gmap->mm->mmap_sem);
        if (flush)
                gmap_flush_tlb(gmap);