This patch is causing a build error for me on 4.3-rc7. CC arch/mips/kernel/signal.o arch/mips/kernel/signal.c: In function 'sc_to_extcontext': arch/mips/kernel/signal.c:143:12: error: 'struct ucontext' has no member named 'uc_extcontext' return &uc->uc_extcontext; ^ In file included from include/linux/poll.h:11:0, from include/linux/ring_buffer.h:7, from include/linux/trace_events.h:5, from include/trace/syscall.h:6, from include/linux/syscalls.h:81, from arch/mips/kernel/signal.c:26: arch/mips/kernel/signal.c: In function 'save_msa_extcontext': arch/mips/kernel/signal.c:171:40: error: dereferencing pointer to incomplete type 'struct msa_extcontext' err = __put_user(read_msa_csr(), &msa->csr); ^ ./arch/mips/include/asm/uaccess.h:441:15: note: in definition of macro '__put_user_nocheck' __typeof__(*(ptr)) __pu_val; \ ^ arch/mips/kernel/signal.c:171:9: note: in expansion of macro '__put_user' err = __put_user(read_msa_csr(), &msa->csr); ^ arch/mips/kernel/signal.c:186:20: error: 'MSA_EXTCONTEXT_MAGIC' undeclared (first use in this function) err |= __put_user(MSA_EXTCONTEXT_MAGIC, &msa->ext.magic); ^ ./arch/mips/include/asm/uaccess.h:444:14: note: in definition of macro '__put_user_nocheck' __pu_val = (x); \ ^ arch/mips/kernel/signal.c:186:9: note: in expansion of macro '__put_user' err |= __put_user(MSA_EXTCONTEXT_MAGIC, &msa->ext.magic); ^ arch/mips/kernel/signal.c:186:20: note: each undeclared identifier is reported only once for each function it appears in err |= __put_user(MSA_EXTCONTEXT_MAGIC, &msa->ext.magic); ^ ./arch/mips/include/asm/uaccess.h:444:14: note: in definition of macro '__put_user_nocheck' __pu_val = (x); \ ^ arch/mips/kernel/signal.c:186:9: note: in expansion of macro '__put_user' err |= __put_user(MSA_EXTCONTEXT_MAGIC, &msa->ext.magic); ^ ....... When I include uapi/asm/ucontext.h instead of asm/ucontext.h in signal.c it compiles again. Hauke