um: Fix __swp_type()

The current __swp_type() function uses a too small bitshift.
Using more than one swap files causes bad pages because
the type bits clash with other page flags.

CC: stable@kernel.org
Analyzed-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index 294254e..5888f1b 100644 (file)
--- a/arch/um/include/asm/pgtable.h
+++ b/arch/um/include/asm/pgtable.h
@@ -354,11 +354,11 @@ extern pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr);
 #define update_mmu_cache(vma,address,ptep) do ; while (0)
 
 /* Encode and de-code a swap entry */
-#define __swp_type(x)                  (((x).val >> 4) & 0x3f)
+#define __swp_type(x)                  (((x).val >> 5) & 0x1f)
 #define __swp_offset(x)                        ((x).val >> 11)
 
 #define __swp_entry(type, offset) \
-       ((swp_entry_t) { ((type) << 4) | ((offset) << 11) })
+       ((swp_entry_t) { ((type) << 5) | ((offset) << 11) })
 #define __pte_to_swp_entry(pte) \
        ((swp_entry_t) { pte_val(pte_mkuptodate(pte)) })
 #define __swp_entry_to_pte(x)          ((pte_t) { (x).val })