From: Yuri Tikhonov <yur@emcraft•com>
To: linux-kernel@vger•kernel.org
Cc: wd@denx•de, dzu@denx•de, miltonm@bga•com,
linuxppc-dev@ozlabs•org, paulus@samba•org,
viro@zeniv•linux.org.uk, Geert.Uytterhoeven@sonycom•com,
hugh@veritas•com, akpm@linux-foundation•org, yanok@emcraft•com
Subject: [PATCH] mm/shmem.c: fix division by zero
Date: Fri, 19 Dec 2008 08:44:57 +0300 [thread overview]
Message-ID: <200812190844.57996.yur@emcraft.com> (raw)
The following patch fixes division by zero, which we have in
shmem_truncate_range() and shmem_unuse_inode(), if use big
PAGE_SIZE values (e.g. 256KB on ppc44x).
With 256KB PAGE_SIZE the ENTRIES_PER_PAGEPAGE constant becomes
too large (0x1.0000.0000), so this patch just changes the types
from 'ulong' to 'ullong' where it's necessary.
Signed-off-by: Yuri Tikhonov <yur@emcraft•com>
---
mm/shmem.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index 0ed0752..99d7c91 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -57,7 +57,7 @@
#include <asm/pgtable.h>
#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
-#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
+#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
@@ -95,7 +95,7 @@ static unsigned long shmem_default_max_inodes(void)
}
#endif
-static int shmem_getpage(struct inode *inode, unsigned long idx,
+static int shmem_getpage(struct inode *inode, unsigned long long idx,
struct page **pagep, enum sgp_type sgp, int *type);
static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
@@ -533,7 +533,7 @@ static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
int punch_hole;
spinlock_t *needs_lock;
spinlock_t *punch_lock;
- unsigned long upper_limit;
+ unsigned long long upper_limit;
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
@@ -1175,7 +1175,7 @@ static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
* vm. If we swap it in we mark it dirty since we also free the swap
* entry since a page cannot live in both the swap and page cache
*/
-static int shmem_getpage(struct inode *inode, unsigned long idx,
+static int shmem_getpage(struct inode *inode, unsigned long long idx,
struct page **pagep, enum sgp_type sgp, int *type)
{
struct address_space *mapping = inode->i_mapping;
--
1.6.0.4
next reply other threads:[~2008-12-19 5:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-19 5:44 Yuri Tikhonov [this message]
2008-12-19 21:24 ` [PATCH] mm/shmem.c: fix division by zero Andrew Morton
2008-12-23 0:35 ` Hugh Dickins
2008-12-23 14:52 ` Re[2]: " Yuri Tikhonov
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