The patch titled
shmem: fix division by zero
has been removed from the -mm tree. Its filename was
shmem-fix-division-by-zero.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: shmem: fix division by zero
From: Yuri Tikhonov <yur@xxxxxxxxxxx>
Fix a division by zero which we have in shmem_truncate_range() and
shmem_unuse_inode() when using big PAGE_SIZE values (e.g. 256kB on
ppc44x).
With 256kB PAGE_SIZE, the ENTRIES_PER_PAGEPAGE constant becomes too large
(0x1.0000.0000) on a 32-bit kernel, so this patch just changes its type
from 'unsigned long' to 'unsigned long long'.
Hugh: reverted its unsigned long longs in shmem_truncate_range() and
shmem_getpage(): the pagecache index cannot be more than an unsigned long,
so the divisions by zero occurred in unreached code. It's a pity we need
any ULL arithmetic here, but I found no pretty way to avoid it.
Signed-off-by: Yuri Tikhonov <yur@xxxxxxxxxxx>
Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/shmem.c~shmem-fix-division-by-zero mm/shmem.c
--- a/mm/shmem.c~shmem-fix-division-by-zero
+++ a/mm/shmem.c
@@ -66,7 +66,7 @@ static struct vfsmount *shm_mnt;
#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))
_
Patches currently in -mm which might be from yur@xxxxxxxxxxx are
origin.patch
powerpc-allow-256kb-pages-with-shmem.patch
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