Re: [PATCH v4 2/4] mm/migrate_device.c: Add missing flush_cache_page()

[Peter Xu <peterx@redhat.com>]

On Fri, Sep 02, 2022 at 10:35:52AM +1000, Alistair Popple wrote:
> Currently we only call flush_cache_page() for the anon_exclusive case,
> however in both cases we clear the pte so should flush the cache.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Fixes: 8c3328f1f36a ("mm/migrate: migrate_vma() unmap page from vma while collecting pages")
> Cc: stable@vger.kernel.org

This is the patch to start collide with David's.

David's patch has also unified both paths with ptep_get_and_clear(), but
this patch itself is also correct to me.

It'll probably just become no-diff after rebase, though.. I'm not sure how
the ordering would be at last, but anyway I think this patch stands as its
own too..

Acked-by: Peter Xu <peterx@redhat.com>

Thanks for tolerant with my nitpickings,

> 
> ---
> 
> New for v4
> ---
>  mm/migrate_device.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/migrate_device.c b/mm/migrate_device.c
> index 6a5ef9f..4cc849c 100644
> --- a/mm/migrate_device.c
> +++ b/mm/migrate_device.c
> @@ -193,9 +193,9 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
>  			bool anon_exclusive;
>  			pte_t swp_pte;
>  
> +			flush_cache_page(vma, addr, pte_pfn(*ptep));
>  			anon_exclusive = PageAnon(page) && PageAnonExclusive(page);
>  			if (anon_exclusive) {
> -				flush_cache_page(vma, addr, pte_pfn(*ptep));
>  				ptep_clear_flush(vma, addr, ptep);
>  
>  				if (page_try_share_anon_rmap(page)) {
> -- 
> git-series 0.9.1
> 

-- 
Peter Xu