The patch titled shmem: fix division by zero has been added to the -mm tree. Its filename is shmem-fix-division-by-zero.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this 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 shmem-fix-division-by-zero.patch shmem-respect-max_lfs_filesize.patch powerpc-allow-256kb-pages-with-shmem.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html