Re: [PATCH v1 2/3] mm/gup: use gup_can_follow_protnone() also in GUP-fast

[David Hildenbrand <david@redhat.com>]

>>>> diff --git a/mm/ksm.c b/mm/ksm.c
>>>> index d7526c705081..971cf923c0eb 100644
>>>> --- a/mm/ksm.c
>>>> +++ b/mm/ksm.c
>>>> @@ -1091,6 +1091,7 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
>>>>  			goto out_unlock;
>>>>  		}
>>>>  
>>>> +		/* See page_try_share_anon_rmap(): clear PTE first. */
>>>>  		if (anon_exclusive && page_try_share_anon_rmap(page)) {
>>>>  			set_pte_at(mm, pvmw.address, pvmw.pte, entry);
>>>>  			goto out_unlock;
>>>> diff --git a/mm/migrate_device.c b/mm/migrate_device.c
>>>> index 27fb37d65476..47e955212f15 100644
>>>> --- a/mm/migrate_device.c
>>>> +++ b/mm/migrate_device.c
>>>> @@ -193,20 +193,16 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
>>>>  			bool anon_exclusive;
>>>>  			pte_t swp_pte;
>>>>  
>>>
>>> flush_cache_page() missing here?
>>
>> Hmm, wouldn't that already be missing on the !anon path right now?
> 
> Yes, I think Alistair plans to fix it too in the other patchset.  So either
> this will rebase to that or it should fix it too.  Thanks,
> 

I'll include it in this patch for now, because by dropping it I would
make the situation "worse". But most probably we want a separate fix
upfront that we can properly backport to older kernels.

Thanks!

-- 
Thanks,

David / dhildenb