Re: [PATCH v1 4/4] mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables using mmu_gather

[David Hildenbrand (Red Hat)]

On 12/7/25 13:24, Nadav Amit wrote:
> > On 7 Dec 2025, at 14:15, Nadav Amit <nadav.amit@xxxxxxxxx> wrote:
> >
> >
> > > On 5 Dec 2025, at 23:35, David Hildenbrand (Red Hat) <david@xxxxxxxxxx> wrote:
> > >
> > > @@ -400,6 +411,7 @@ static inline void __tlb_reset_range(struct mmu_gather *tlb)
> >
> > @@ -400,6 +411,7 @@ static inline void __tlb_reset_range(struct mmu_gather *tlb)
> > 	tlb->cleared_pmds = 0;
> > 	tlb->cleared_puds = 0;
> > 	tlb->cleared_p4ds = 0;
> > +	tlb->unshared_tables = 0;
> > 	/*
> > 	 * Do not reset mmu_gather::vma_* fields here, we do not
> > 	 * call into tlb_start_vma() again to set them if there is an
> >
> > I understand you don’t want to initialize fully_unshared_tables here, but
> > tlb_gather_mmu() needs to happen somewhere. So you probably want it to
> > take place in tlb_gather_mmu(), no?
>
> To clarify my messed up response: the code needs to initialize fully_unshared_tables
> somewhere during tlb_gather_mmu() invocation.

Good point, __tlb_gather_mmu() needs to initialize it explicitly!

Thanks a lot for the review, appreciated!

--
Cheers

David