From: Michael Marineau When tmpfs is mounted with a size less than one page, the number of blocks is set to 0 which makes the tmpfs mount unlimited. This can lead to a quick and surprising death if someone typos a tmpfs mount command and writes too much. tmpfs can still be mounted as unlimited if size or nr_blocks is exactly 0, as Documentation/filesystems/tmpfs.txt says. Hugh: do this by rounding size up instead of down in all cases: which slightly expands other odd-sized tmpfs mounts, but in a consistent way. Signed-off-by: Michael Marineau Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton --- mm/shmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN mm/shmem.c~tmpfs-fix-mounts-when-size-is-less-than-the-page-size mm/shmem.c --- a/mm/shmem.c~tmpfs-fix-mounts-when-size-is-less-than-the-page-size +++ a/mm/shmem.c @@ -2012,7 +2012,7 @@ static int shmem_parse_options(char *opt } if (*rest) goto bad_val; - *blocks = size >> PAGE_CACHE_SHIFT; + *blocks = DIV_ROUND_UP(size, PAGE_CACHE_SIZE); } else if (!strcmp(this_char,"nr_blocks")) { *blocks = memparse(value,&rest); if (*rest) _