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

["David Hildenbrand (Red Hat)" <david@kernel.org>]

On 12/7/25 13:24, Nadav Amit wrote:
> 
> 
>> On 7 Dec 2025, at 14:15, Nadav Amit <nadav.amit@gmail.com> wrote:
>>
>>
>>> On 5 Dec 2025, at 23:35, David Hildenbrand (Red Hat) <david@kernel.org> 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