linux-kernel - [PATCH 2/2] um: Fix __swp

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Date:	Sat, 14 Apr 2012 17:52:11 +0200
From:	Richard Weinberger <richard@....at>
To:	user-mode-linux-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org, hughd@...gle.com,
	Richard Weinberger <richard@....at>, stable@...nel.org
Subject: [PATCH 2/2] 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@...nel.org
Analyzed-by: Hugh Dickins <hughd@...gle.com>
Signed-off-by: Richard Weinberger <richard@....at>
---
 arch/um/include/asm/pgtable.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index 294254e..5888f1b 100644
--- 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 })
-- 
1.7.7.3

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