mm/shmem.c in the Linux kernel through 3.15.1 does not properly implement the interaction between range notification and hole punching, which allows local users to cause a denial of service (i_mutex hold) by using the mmap system call to access a hole, as demonstrated by interfering with intended shmem activity by blocking completion of (1) an MADV_REMOVE madvise call or (2) an FALLOC_FL_PUNCH_HOLE fallocate call.