error invalid application of sizeof to incomplete type struct pt_regs

  CC      arch/mips/xburst2/common/mxuv3.o
  CC      arch/mips/xburst2/core/smp.o
In file included from ./arch/mips/include/asm/thread_info.h:15:0,
                 from ./include/linux/thread_info.h:37,
                 from ./include/asm-generic/current.h:4,
                 from ./arch/mips/include/generated/asm/current.h:1,
                 from ./include/linux/sched.h:11,
                 from ./include/linux/sched/task_stack.h:8,
                 from arch/mips/xburst2/common/mxuv3.c:1:
arch/mips/xburst2/common/mxuv3.c: In function '__init_mxuv3':
./arch/mips/include/asm/processor.h:414:31: error: invalid application of 'sizeof' to incomplete type 'struct pt_regs'
     THREAD_SIZE - 32 - sizeof(struct pt_regs))
                               ^

#include <linux/ptrace.h>