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

[Ryan Roberts]

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@xxxxxxxxxx>
>>> ---
>>>   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.

> 
> Will fix, thanks!
>