Re: [intel-linux-intel-lts:4.19/android_r 20723/22085] include/linux/page-flags-layout.h:95:2: error: #error "Not enough bits in page flags"

[Arnd Bergmann <arnd@arndb.de>]

On Tue, Mar 9, 2021 at 4:00 PM kernel test robot <lkp@intel.com> wrote:
>
> tree:   https://github.com/intel/linux-intel-lts.git 4.19/android_r
> head:   42da0a5bc28f55c05347ef8eb88d9e41f369333e
> commit: 7783c5c8ec0d6781dc180be5fd075f06f90e9cb5 [20723/22085] UPSTREAM: page flags: prioritize kasan bits over last-cpuid
> config: mips-lemote2f_defconfig (attached as .config)
> compiler: mips64el-linux-gcc (GCC) 9.3.0
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://github.com/intel/linux-intel-lts/commit/7783c5c8ec0d6781dc180be5fd075f06f90e9cb5
>         git remote add intel-linux-intel-lts https://github.com/intel/linux-intel-lts.git
>         git fetch --no-tags intel-linux-intel-lts 4.19/android_r
>         git checkout 7783c5c8ec0d6781dc180be5fd075f06f90e9cb5
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
> All errors (new ones prefixed by >>):
>
>    In file included from include/linux/mm_types.h:15,
>                     from arch/mips/include/asm/vdso.h:14,
>                     from arch/mips/include/asm/vdso/vdso.h:28,
>                     from arch/mips/include/asm/vdso/gettimeofday.h:16,
>                     from include/vdso/datapage.h:114,
>                     from lib/vdso/gettimeofday.c:5,
>                     from <command-line>:
> >> include/linux/page-flags-layout.h:95:2: error: #error "Not enough bits in page flags"

I think this happens because my patch fixed an error that happened on
multiple architectures but did not fix the mips specific error that remains.

I once tried fixing this as well, but there is no good way to express the
requirements in Kconfig -- there are simply not enough bits in the
page flags to allow all combinations that can happen in randconfig
builds.

       Arnd