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

[David Hildenbrand]

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@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.

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

--
Cheers,

David / dhildenb