On Wed, 9 Feb 2022 20:44:02 -0800 (PST) Hugh Dickins <hughd@xxxxxxxxxx> wrote:
> From: SeongJae Park <sj@xxxxxxxxxx>
>
> Commit 4b3b8bd6c8287 ("mm/munlock: mlock_page() munlock_page() batch by
> pagevec") in -mm tree[1] implements 'mlock_page_drain()' under
> CONFIG_MMU only, but the function is used by 'lru_add_drain_cpu()',
> which defined outside of CONFIG_MMU. As a result, below build error
> occurs.
>
> /linux/mm/swap.c: In function 'lru_add_drain_cpu':
> /linux/mm/swap.c:637:2: error: implicit declaration of function 'mlock_page_drain' [-Werror=implicit-function-declaration]
> 637 | mlock_page_drain(cpu);
> | ^~~~~~~~~~~~~~~~
> cc1: some warnings being treated as errors
> /linux/scripts/Makefile.build:289: recipe for target 'mm/swap.o' failed
>
> This commit fixes it by implementing no-op 'mlock_page_drain()' for
> !CONFIG_MMU case, similar to 'mlock_new_page()'.
>
> [1] https://www.ozlabs.org/~akpm/mmotm/broken-out/mm-munlock-mlock_page-munlock_page-batch-by-pagevec.patch
>
> [hughd: add need_mlock_page_drain() stub too]
> Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
> Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
> ---
> Andrew, Stephen, please add as fix to
> mm-munlock-mlock_page-munlock_page-batch-by-pagevec.patch
> Thanks!
Thank you, Hugh!
Thanks,
SJ
>
> mm/internal.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -508,6 +508,8 @@ static inline void mlock_vma_page(struct page *page,
> static inline void munlock_vma_page(struct page *page,
> struct vm_area_struct *vma, bool compound) { }
> static inline void mlock_new_page(struct page *page) { }
> +static inline bool need_mlock_page_drain(int cpu) { return false; }
> +static inline void mlock_page_drain(int cpu) { }
> static inline void vunmap_range_noflush(unsigned long start, unsigned long end)
> {
> }
>
