linux-kernel - Re: [PATCH v4 36/66] um: Remove vma linked list walk

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Date:   Tue, 18 Jan 2022 19:41:04 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Liam Howlett <liam.howlett@...cle.com>,
        "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Song Liu <songliubraving@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Rik van Riel <riel@...riel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michel Lespinasse <walken.cr@...il.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Minchan Kim <minchan@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Rom Lemarchand <romlem@...gle.com>
Subject: Re: [PATCH v4 36/66] um: Remove vma linked list walk

On 12/1/21 15:30, Liam Howlett wrote:
> From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
> 
> Use the VMA iterator instead.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> ---
>  arch/um/kernel/tlb.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
> index bc38f79ca3a3..25f043037d76 100644
> --- a/arch/um/kernel/tlb.c
> +++ b/arch/um/kernel/tlb.c
> @@ -584,21 +584,19 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
>  
>  void flush_tlb_mm(struct mm_struct *mm)
>  {
> -	struct vm_area_struct *vma = mm->mmap;
> +	struct vm_area_struct *vma;
> +	VMA_ITERATOR(vmi, mm, 0);
>  
> -	while (vma != NULL) {
> +	for_each_vma(vmi, vma)
>  		fix_range(mm, vma->vm_start, vma->vm_end, 0);
> -		vma = vma->vm_next;
> -	}
>  }
>  
>  void force_flush_all(void)
>  {
>  	struct mm_struct *mm = current->mm;
> -	struct vm_area_struct *vma = mm->mmap;
> +	struct vm_area_struct *vma;
> +	MA_STATE(mas, &mm->mm_mt, 0, 0);
>  
> -	while (vma != NULL) {
> +	mas_for_each(&mas, vma, ULONG_MAX)

Is there a reason to use the iterator in one case and mas_for_each in the other?

>  		fix_range(mm, vma->vm_start, vma->vm_end, 1);
> -		vma = vma->vm_next;
> -	}
>  }