linux-kernel - Re: [PATCH 01/11] mm: page_vma_mapped

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Message-ID: <20210610085522.f5ffyejzn3xtqark@box.shutemov.name>
Date:   Thu, 10 Jun 2021 11:55:22 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Hugh Dickins <hughd@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Yang Shi <shy828301@...il.com>,
        Wang Yugui <wangyugui@...-tech.com>,
        Matthew Wilcox <willy@...radead.org>,
        Alistair Popple <apopple@...dia.com>,
        Ralph Campbell <rcampbell@...dia.com>, Zi Yan <ziy@...dia.com>,
        Peter Xu <peterx@...hat.com>, Will Deacon <will@...nel.org>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/11] mm: page_vma_mapped_walk(): use page for pvmw->page

On Wed, Jun 09, 2021 at 11:34:40PM -0700, Hugh Dickins wrote:
> page_vma_mapped_walk() cleanup: sometimes the local copy of pvwm->page was
> used, sometimes pvmw->page itself: use the local copy "page" throughout.
> 
> Signed-off-by: Hugh Dickins <hughd@...gle.com>
> Cc: <stable@...r.kernel.org>

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

A question below.

> ---
>  mm/page_vma_mapped.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> index e37bd43904af..a6dbf714ca15 100644
> --- a/mm/page_vma_mapped.c
> +++ b/mm/page_vma_mapped.c
> @@ -156,7 +156,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
>  	if (pvmw->pte)
>  		goto next_pte;
>  
> -	if (unlikely(PageHuge(pvmw->page))) {
> +	if (unlikely(PageHuge(page))) {
>  		/* when pud is not present, pte will be NULL */
>  		pvmw->pte = huge_pte_offset(mm, pvmw->address, page_size(page));
>  		if (!pvmw->pte)
> @@ -217,8 +217,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
>  		 * cannot return prematurely, while zap_huge_pmd() has
>  		 * cleared *pmd but not decremented compound_mapcount().
>  		 */
> -		if ((pvmw->flags & PVMW_SYNC) &&
> -		    PageTransCompound(pvmw->page)) {
> +		if ((pvmw->flags & PVMW_SYNC) && PageTransCompound(page)) {
>  			spinlock_t *ptl = pmd_lock(mm, pvmw->pmd);
>  
>  			spin_unlock(ptl);
> @@ -234,9 +233,9 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
>  			return true;
>  next_pte:
>  		/* Seek to next pte only makes sense for THP */
> -		if (!PageTransHuge(pvmw->page) || PageHuge(pvmw->page))
> +		if (!PageTransHuge(page) || PageHuge(page))
>  			return not_found(pvmw);
> -		end = vma_address_end(pvmw->page, pvmw->vma);
> +		end = vma_address_end(page, pvmw->vma);
>  		do {
>  			pvmw->address += PAGE_SIZE;
>  			if (pvmw->address >= end)

I see two more pvmw->page in this loop. Do you leave them here as the code
will be rewritten later in the patchset?

-- 
 Kirill A. Shutemov