On Mon, May 24, 2021 at 05:13:02PM -0700, Randy Dunlap wrote:
> Fix a Kconfig warning and many build errors:
>
> WARNING: unmet direct dependencies detected for COMPACTION
> Depends on [n]: MMU [=n]
> Selected by [y]:
> - TRANSPARENT_HUGEPAGE [=y] && HAVE_ARCH_TRANSPARENT_HUGEPAGE [=y]
>
> and the subseqent thousands of build errors and warnings.
>
> Fixes: e88b333142e4 ("riscv: mm: add THP support on 64-bit")
> Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
> Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
> Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
> Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Nanyong Sun <sunnanyong@xxxxxxxxxx>
Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> ---
> I really think that mm/Kconfig should have "depends on MMU" for
> TRANSPARENT_HUGEPAGE, but commit 15626062f4a9 from 2012
> ("thp, x86: introduce HAVE_ARCH_TRANSPARENT_HUGEPAGE") thought
> differently. I.e., mm/Kconfig should be protecting all arches
> against this Kconfig problem.
We could
diff --git a/mm/Kconfig b/mm/Kconfig
index 02d44e3420f5..85bc8bf32e7b 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -403,7 +403,7 @@ config NOMMU_INITIAL_TRIM_EXCESS
config TRANSPARENT_HUGEPAGE
bool "Transparent Hugepage Support"
- depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
+ depends on MMU && HAVE_ARCH_TRANSPARENT_HUGEPAGE
select COMPACTION
select XARRAY_MULTI
help
but in a sense HAVE_ARCH_TRANSPARENT_HUGEPAGE should imply that MMU is
selected :)
> arch/riscv/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- linux-next-20210524.orig/arch/riscv/Kconfig
> +++ linux-next-20210524/arch/riscv/Kconfig
> @@ -106,7 +106,7 @@ config RISCV
> select SYSCTL_EXCEPTION_TRACE
> select THREAD_INFO_IN_TASK
> select UACCESS_MEMCPY if !MMU
> - select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT
> + select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU
>
> config ARCH_MMAP_RND_BITS_MIN
> default 18 if 64BIT
>
--
Sincerely yours,
Mike.
