Re: [PATCH v1 1/9] mm/memory: factor out zapping of present pte into zap_present_pte()

David Hildenbrand
2024-01-30T08:49:05Z

On 30.01.24 09:46, Ryan Roberts wrote:
> On 30/01/2024 08:41, David Hildenbrand wrote:
>> On 30.01.24 09:13, Ryan Roberts wrote:
>>> On 29/01/2024 14:32, David Hildenbrand wrote:
>>>> Let's prepare for further changes by factoring out processing of present
>>>> PTEs.
>>>>
>>>> Signed-off-by: David Hildenbrand <david@redhat.com>
>>>> ---
>>>>   mm/memory.c | 92 ++++++++++++++++++++++++++++++-----------------------
>>>>   1 file changed, 52 insertions(+), 40 deletions(-)
>>>>
>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>> index b05fd28dbce1..50a6c79c78fc 100644
>>>> --- a/mm/memory.c
>>>> +++ b/mm/memory.c
>>>> @@ -1532,13 +1532,61 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct
>>>> *vma,
>>>>       pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
>>>>   }
>>>>   +static inline void zap_present_pte(struct mmu_gather *tlb,
>>>> +        struct vm_area_struct *vma, pte_t *pte, pte_t ptent,
>>>> +        unsigned long addr, struct zap_details *details,
>>>> +        int *rss, bool *force_flush, bool *force_break)
>>>> +{
>>>> +    struct mm_struct *mm = tlb->mm;
>>>> +    bool delay_rmap = false;
>>>> +    struct folio *folio;
>>>
>>> You need to init this to NULL otherwise its a random value when calling
>>> should_zap_folio() if vm_normal_page() returns NULL.
>>
>> Right, and we can stop setting it to NULL in the original function. Patch #2
>> changes these checks, which is why it's only a problem in this patch.
>
> Yeah I only noticed that after sending out this reply and moving to the next
> patch. Still worth fixing this intermediate state I think.

Absolutely, I didn't do path-by-patch compilation yet (I suspect the
compiler would complain).

--
Cheers,

David / dhildenb