On Sat, Sep 25, 2021 at 01:54:22PM -0700, Nadav Amit wrote:
> @@ -338,25 +344,25 @@ static unsigned long change_protection_range(struct vm_area_struct *vma,
> struct mm_struct *mm = vma->vm_mm;
> pgd_t *pgd;
> unsigned long next;
> - unsigned long start = addr;
> unsigned long pages = 0;
> + struct mmu_gather tlb;
>
> BUG_ON(addr >= end);
> pgd = pgd_offset(mm, addr);
> flush_cache_range(vma, addr, end);
> inc_tlb_flush_pending(mm);
That seems unbalanced...
> + tlb_gather_mmu(&tlb, mm);
> + tlb_start_vma(&tlb, vma);
> do {
> next = pgd_addr_end(addr, end);
> if (pgd_none_or_clear_bad(pgd))
> continue;
> - pages += change_p4d_range(vma, pgd, addr, next, newprot,
> + pages += change_p4d_range(&tlb, vma, pgd, addr, next, newprot,
> cp_flags);
> } while (pgd++, addr = next, addr != end);
>
> - /* Only flush the TLB if we actually modified any entries: */
> - if (pages)
> - flush_tlb_range(vma, start, end);
> - dec_tlb_flush_pending(mm);
... seeing you do remove the extra decrement.
> + tlb_end_vma(&tlb, vma);
> + tlb_finish_mmu(&tlb);
>
> return pages;
> }
> --
> 2.25.1
>
