Re: [PATCH v2] hugetlb: allow to free gigantic pages regardless of the configuration

[Alexandre Ghiti]

On 02/13/2019 08:30 PM, Dave Hansen wrote:

-#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || 
defined(CONFIG_CMA)
+#ifdef CONFIG_COMPACTION_CORE
  static __init int gigantic_pages_init(void)
  {
        /* With compaction or CMA we can allocate gigantic pages at runtime */
diff --git a/fs/Kconfig b/fs/Kconfig
index ac474a61be37..8fecd3ea5563 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -207,8 +207,9 @@ config HUGETLB_PAGE
  config MEMFD_CREATE
        def_bool TMPFS || HUGETLBFS

-config ARCH_HAS_GIGANTIC_PAGE

+config COMPACTION_CORE
        bool
+       default y if (MEMORY_ISOLATION && MIGRATION) || CMA

This takes a hard dependency (#if) and turns it into a Kconfig *default*
that can be overridden.  That seems like trouble.

Shouldn't it be:

config COMPACTION_CORE
        def_bool y
        depends on (MEMORY_ISOLATION && MIGRATION) || CMA

?

Thanks for that,

Alex