Re: [Xen-devel] [PATCH v2] x86: enable RCU based table free

[Peter Zijlstra <peterz@xxxxxxxxxxxxx>]

On Thu, Aug 24, 2017 at 11:22:58AM +0200, Vitaly Kuznetsov wrote:

> diff --git a/arch/x86/include/asm/tlb.h b/arch/x86/include/asm/tlb.h
> index c7797307fc2b..d43a7fcafee9 100644
> --- a/arch/x86/include/asm/tlb.h
> +++ b/arch/x86/include/asm/tlb.h
> @@ -15,4 +15,9 @@
>  
>  #include <asm-generic/tlb.h>
>  
> +static inline void __tlb_remove_table(void *table)
> +{
> +     free_page_and_swap_cache(table);
> +}

Most other archs have this in pgtable.h, only ARM* has it in tlb.h.

And should we put a comment on explaining _why_ we have RCU_TABLE_FREE
enabled?

>  #endif /* _ASM_X86_TLB_H */
> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
> index 508a708eb9a6..218834a3e9ad 100644
> --- a/arch/x86/mm/pgtable.c
> +++ b/arch/x86/mm/pgtable.c
> @@ -56,7 +56,7 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page 
> *pte)
>  {
>       pgtable_page_dtor(pte);
>       paravirt_release_pte(page_to_pfn(pte));
> -     tlb_remove_page(tlb, pte);
> +     tlb_remove_table(tlb, pte);
>  }
>  
>  #if CONFIG_PGTABLE_LEVELS > 2
> @@ -72,21 +72,21 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
>       tlb->need_flush_all = 1;
>  #endif
>       pgtable_pmd_page_dtor(page);
> -     tlb_remove_page(tlb, page);
> +     tlb_remove_table(tlb, page);
>  }
>  
>  #if CONFIG_PGTABLE_LEVELS > 3
>  void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
>  {
>       paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
> -     tlb_remove_page(tlb, virt_to_page(pud));
> +     tlb_remove_table(tlb, virt_to_page(pud));
>  }
>  
>  #if CONFIG_PGTABLE_LEVELS > 4
>  void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d)
>  {
>       paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT);
> -     tlb_remove_page(tlb, virt_to_page(p4d));
> +     tlb_remove_table(tlb, virt_to_page(p4d));
>  }
>  #endif       /* CONFIG_PGTABLE_LEVELS > 4 */
>  #endif       /* CONFIG_PGTABLE_LEVELS > 3 */
> -- 
> 2.13.5
> 

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