Re: [PATCH v2 2/2] mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to MM CPUs

Nadav Amit
2023-06-21T18:02:23Z

>
> On Jun 20, 2023, at 7:46 AM, Yair Podemsky <ypodemsk@redhat.com> wrote:
>
> @@ -1525,7 +1525,7 @@ static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *v
> addr + HPAGE_PMD_SIZE);
> mmu_notifier_invalidate_range_start(&range);
> pmd = pmdp_collapse_flush(vma, addr, pmdp);
> - tlb_remove_table_sync_one();
> + tlb_remove_table_sync_one(mm);

Can’t pmdp_collapse_flush() have one additional argument “freed_tables”
that it would propagate, for instance on x86 to flush_tlb_mm_range() ?
Then you would not need tlb_remove_table_sync_one() to issue an additional
IPI, no?

It just seems that you might still have 2 IPIs in many cases instead of
one, and unless I am missing something, I don’t see why.