On Tue, Dec 11, 2018 at 09:04:43PM +0100, Arnd Bergmann wrote:
> The macro version of mmu_notifier_range_init() for CONFIG_MMU_NOTIFIER=n
> does not evaluate all its arguments, leading to a warning in one case:
>
> mm/migrate.c: In function 'migrate_vma_pages':
> mm/migrate.c:2711:20: error: unused variable 'mm' [-Werror=unused-variable]
> struct mm_struct *mm = vma->vm_mm;
>
> Pass down the 'mm' as into the inline function as well so gcc can
> see why the variable exists.
>
> Fixes: 137d92bd73b1 ("mm/mmu_notifier: use structure for
> invalidate_range_start/end calls v2")
What about changing migrate.c (i actualy tried to do that everywhere in
the patchset but i missed that spot) So we avoid one useless variable on
such configuration:
diff --git a/mm/migrate.c b/mm/migrate.c
index f02bb4b22c1a..883fce631f47 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2701,7 +2701,6 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
const unsigned long npages = migrate->npages;
const unsigned long start = migrate->start;
struct vm_area_struct *vma = migrate->vma;
- struct mm_struct *mm = vma->vm_mm;
struct mmu_notifier_range range;
unsigned long addr, i;
bool notified = false;
@@ -2724,8 +2723,8 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
if (!notified) {
notified = true;
- mmu_notifier_range_init(&range, mm, addr,
- migrate->end,
+ mmu_notifier_range_init(&range, vma->vm_mm,
+ addr, migrate->end,
MMU_NOTIFY_CLEAR);
mmu_notifier_invalidate_range_start(&range);
}
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> include/linux/mmu_notifier.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
> index 29f7b9670ba3..b13ea00ded5d 100644
> --- a/include/linux/mmu_notifier.h
> +++ b/include/linux/mmu_notifier.h
> @@ -476,6 +476,7 @@ struct mmu_notifier_range {
> };
>
> static inline void _mmu_notifier_range_init(struct mmu_notifier_range *range,
> + struct mm_struct *mm,
> unsigned long start,
> unsigned long end)
> {
> @@ -484,7 +485,7 @@ static inline void _mmu_notifier_range_init(struct
> mmu_notifier_range *range,
> }
>
> #define mmu_notifier_range_init(range, mm, start, end, event) \
> - _mmu_notifier_range_init(range, start, end)
> + _mmu_notifier_range_init(range, mm, start, end)
>
>
> static inline int mm_has_notifiers(struct mm_struct *mm)
> --
> 2.20.0
>
