Hi Matthew, Thank you for the patch! Yet something to improve: [auto build test ERROR on ia64/next] [also build test ERROR on m68k/for-next s390/features linus/master v5.7-rc1 next-20200416] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Matthew-Wilcox/Make-PageWritebac... base: https://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux.git next config: ia64-allmodconfig (attached as .config) compiler: ia64-linux-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day GCC_VERSION=9.3.0 make.cross ARCH=ia64 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): WARNING: unmet direct dependencies detected for FRAME_POINTER Depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS Selected by - FAULT_INJECTION_STACKTRACE_FILTER && FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT && !X86_64 && !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 scripts/Makefile.build:59: 'arch/ia64/kernel/palinfo.ko' 'arch/ia64/kernel/mca_recovery.ko' 'arch/ia64/kernel/err_inject.ko' will not be built even though obj-m is specified. scripts/Makefile.build:60: You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead. In file included from include/linux/bitops.h:29, from include/linux/kernel.h:12, from include/asm-generic/bug.h:19, from arch/ia64/include/asm/bug.h:17, from include/linux/bug.h:5, from include/linux/page-flags.h:10, from kernel/bounds.c:10: arch/ia64/include/asm/bitops.h: In function 'clear_bit_unlock_is_negative_byte': 127 | m = (volatile __u32 addr + (nr >> 5); | ^~~~ arch/ia64/include/asm/bitops.h:127:25: note: each undeclared identifier is reported only once for each function it appears in Makefile Module.symvers System.map arch block certs crypto drivers fs include init ipc kernel lib mm modules.builtin modules.builtin.modinfo modules.order net scripts security sound source usr virt vmlinux vmlinux.bin vmlinux.gz vmlinux.o [scripts/Makefile.build:101: kernel/bounds.s] Error 1 Target '__build' not remade because of errors. Makefile Module.symvers System.map arch block certs crypto drivers fs include init ipc kernel lib mm modules.builtin modules.builtin.modinfo modules.order net scripts security sound source usr virt vmlinux vmlinux.bin vmlinux.gz vmlinux.o [Makefile:1113: prepare0] Error 2 Target 'prepare' not remade because of errors. make: Makefile Module.symvers System.map arch block certs crypto drivers fs include init ipc kernel lib mm modules.builtin modules.builtin.modinfo modules.order net scripts security sound source usr virt vmlinux vmlinux.bin vmlinux.gz vmlinux.o [Makefile:180: sub-make] Error 2 16 real 4 user 7 sys 70.16% cpu make prepare vim +/addr +127 arch/ia64/include/asm/bitops.h 119 120 static inline bool clear_bit_unlock_is_negative_byte(unsigned int nr, 121 volatile unsigned long *p) 122 { 123 __u32 mask, old, new; 124 volatile __u32 *m; 125 CMPXCHG_BUGCHECK_DECL 126 128 mask = ~(1 << (nr & 31)); 129 do { 130 CMPXCHG_BUGCHECK(m); 131 old = *m; 132 new = old & mask; 133 } while (cmpxchg_rel(m, old, new) != old); 134 135 return old & (1 << 7); 136 } 137 #define clear_bit_unlock_is_negative_byte \ 138 clear_bit_unlock_is_negative_byte 139 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org