From: SeongJae Park <sjpark@xxxxxxxxx> Commit 128fd80c4c07 ("mm/idle_page_tracking: Make PG_idle reusable") of linux-mm[1] allows PAGE_IDLE_FLAG to be set without PAGE_EXTENSION while 64BIT is not set. This makes 'enum page_ext_flags' undefined, so build fails as below for the config (!64BIT, !PAGE_EXTENSION, and IDLE_PAGE_FLAG). $ make ARCH=i386 allnoconfig $ echo 'CONFIG_PAGE_IDLE_FLAG=y' >> .config $ make olddefconfig $ make ARCH=i386 [...] ../include/linux/page_idle.h: In function ‘folio_test_young’: ../include/linux/page_idle.h:25:18: error: ‘PAGE_EXT_YOUNG’ undeclared (first use in this function); did you mean ‘PAGEOUTRUN’? return test_bit(PAGE_EXT_YOUNG, &page_ext->flags); [...] This commit fixes this issue by making PAGE_EXTENSION to be set when 64BIT is not set and PAGE_IDLE_FLAG is set. [1] https://github.com/hnaz/linux-mm/commit/128fd80c4c07 Fixes: 128fd80c4c07 ("mm/idle_page_tracking: Make PG_idle reusable") Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Signed-off-by: SeongJae Park <sjpark@xxxxxxxxx> --- mm/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/Kconfig b/mm/Kconfig index d0b85dc12429..50ca602edeb6 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -741,6 +741,7 @@ config DEFERRED_STRUCT_PAGE_INIT config PAGE_IDLE_FLAG bool "Add PG_idle and PG_young flags" + select PAGE_EXTENSION if !64BIT help This feature adds PG_idle and PG_young flags in 'struct page'. PTE Accessed bit writers can set the state of the bit in the flags to let @@ -749,7 +750,6 @@ config PAGE_IDLE_FLAG config IDLE_PAGE_TRACKING bool "Enable idle page tracking" depends on SYSFS && MMU && BROKEN - select PAGE_EXTENSION if !64BIT select PAGE_IDLE_FLAG help This feature allows to estimate the amount of user pages that have -- 2.17.1