On Tue, 11 Dec 2018, Jerome Glisse wrote:
> 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);
> }
Wouldn't it be better to just declare mmu_notifier_range_init() as a
static inline function rather than a #define to avoid this warning?
